Global disparities in COVID-19 vaccine booster dose (VBD) acceptance and hesitancy: An updated narrative review.

The global deployment of COVID-19 vaccine booster dose (VBD) has been recognized as a promising therapeutic alliance to provide repeated immunity against the arrival of new variants. Despite scientific evidence supports the effectiveness of periodic doses, COVID-19 vaccine booster reluctance continues to thrive. This narrative review aimed to examine global COVID-19 vaccine booster dose (VBD) acceptance and summarize an up-to-date assessment of potential antecedents associated with VBD acceptance. A comprehensive search was performed in several reputable databases such as Medline (via PubMed), Scopus, Google scholar, and Web of Science from June 10th, 2023, to August 1st, 2023. All relevant descriptive and observational studies on COVID-19 VBD acceptance and hesitancy were included in this review. A total of fifty-eight (58) studies were included, with Asia representing the highest count with thirty-one (53%) studies, Europe with eleven (19 %), the United States with nine (16 %), and other regions (Africa and multi-ethnic) with seven (12 %). Worldwide, the pooled COVID-19 VBD acceptance rate was 77.09 % (95 % CI: 76.28-78.18), VBD willingness (n) = 164189, and the total sample (N) = 212,990. The highest and the lowest VBD acceptance rate was reported in Europe and American regions, respectively, 85.38 % (95 % CI: 85.02-85.73, (n) = 32,047, (N = 37,533) vs. 66.92 % (95 % CI: 66.56-67.4), (n) = 29335, (N) = 43,832. However, Asia and multi-ethnic areas reported moderately high VBD acceptance rate 79.13 % (95 % CI: 78.77-79.23, (n) = 93,994, (N) = 11,8779) and 72.16 % (95 % CI: 71.13-72.93, (n) = 9276, (N) = 12,853), respectively. The most common and key antecedents of COVID-19 VBD acceptance and hesitancy across the countries were "equal safety", "efficacy", "effectiveness", "post-vaccination side effects", "community protection" "family protection", "risk-benefit ratio", "booster necessity", "trust", and "variants control". Disparities in the uptake of COVID-19 VBD were observed globally, with the highest rates found in Europe, and the lowest rates in American regions. Multiple potential antecedents including safety, efficacy, and post-vaccination side effects were associated with VBD acceptance and hesitancy.

Acceptance of COVID-19 vaccine booster dose among the people of Bangladesh: A cross-sectional study.

Vaccine booster dose (VBD) provides a potential therapeutic alliance in preventing breakthrough infection and new variant's arrival while preserving long-lasting host immunity. This study aimed to analyze COVID-19 VBD willingness and identified the key determinants of VBD acceptance among the general people of Bangladesh. This survey-based study applied a quantitative research paradigm. A validated, anonymous, and multi-item questionnaire was adopted through a theoretical review of pertinent literature on the topic. Data were collected between August 2022─October 2022, and sampling was done randomly. A total of 704 individuals were invited via face-to-face interview approach; however, 13.8 % of them declined to give consent, which resulted in the participation of 607 potential respondents. The main outcome measure was COVID-19 VBD acceptance willingness. Binary logistic regression analysis was conducted to rationalize the study's objectives. The pooled COVID-19 booster vaccine acceptance rate was 70.0 % (95 % confidence Interval [CI]: 67─73) among Bangladeshi people. An analysis of binary logistic regression revealed that, out of 14 potential factors, "efficacy", "repeated immunity", "communication", and "trust" showed highly significant positive association (adjusted odds ratio [aOR ] = 2.151 95 % CI: 1.391─ 3.508, aOR = 2.033 95 % CI: 1.299─ 3.181, and aOR = 2.552 95 % CI: 1.557─4.183 respectively, p<0.01), and "equal safety", "risk-benefit ratio" and "community protection" had significant positive association (aOR = 1.739 95 % CI: 1.070─2.825, aOR = 1.712 95 % CI: 1.116─2.627, and aOR = 1.628 95 % CI: 1.395─0.998, p<0.05) with VBD acceptance. However, post-vaccination "side effects" showed significant negative (aOR = 0.393 95 % CI: 0.237─0.674, p<0.01) associations with VBD acceptance. The odds of accepting the COVID-19 vaccine booster was found 1.26, and it was found insignificant (p>0.05) in the Chi-squared test. Bangladeshi people expressed a moderately high level response to COVID-19 VBD acceptance. A positive attitude towards the COVID-19 VBD is an outcome of this study, regardless of the circumstances, as far as safety, efficacy, perceived health benefits, communication, trust, and community resistance are concerned. Post-vaccination side effects fear was the primary reason for booster dose skepticism as well as a barrier to administering booster shots. The confidence in COVID-19 VBD will be boosted when mass people are effectively communicated and vaccine's data become more available publicly.

Multi-dimensional potential factors influencing COVID-19 vaccine booster acceptance and hesitancy among university academic community in Bangladesh: A cross-sectional comparative study.

BACKGROUND AND AIMS: Vaccination is the most powerful public health intervention proven to be safe and effective in the battle against the coronavirus disease-2019 (COVID-19) pandemic. Despite the potential therapeutic benefits of primer vaccine dosage regimens, public perceptions of COVID-19 vaccine booster dose (VBD) acceptance and hesitancy vary among various sub-group populations. This study investigates COVID-19 vaccine booster dose acceptance and compares the multi-dimensional potential factors influencing VBD acceptance and hesitancy among university teachers and the student community in Bangladesh. METHODS: This web-based cross-sectional study employed an anonymous, validated, and self-administered questionnaire. The questionnaire items were adopted from a theoretical analysis of the recent relevant literature. The questionnaire was deployed in an on-line-enabled format (Google form) and conveniently distributed to 685 teachers and 990 students between 15th June, 2022 and 15th August, 2022 which resulted in the participation of 1250 (505 teachers vs.745 students) total respondents (response rate 73.72% vs. 75.25%) from various universities in Bangladesh. A non-parametric analytical tool (binary logistic regression) was applied to rationalize the study objectives and a Chi-squared test was performed to estimate the booster- hesitant risky group. RESULTS: The pooled COVID-19 vaccine booster dose acceptance rates were 84.6% (95% CI 81.5─87.7) and 67.2% (95% CI 63.8─70.6) for teachers and students in the university academic community, respectively. In employing a binary logistic regression, this study revealed that out of twelve (12)multi-dimensional key predictors, "equal safety", "risk-benefit ratio", and "variant control" had a significant positive association with VBD acceptance in both sets (p = 0.000, p = 0.000, and p = 0.005, respectively). Varied effects were found for several predictors; post-vaccination "side effects" had a significant negative association (p = 0.020) and "community protection" had significant positive association (p = 0.034) with vaccine booster dose acceptance in the teachers community while these variables were insignificant in the students cohort. "Trust" had a highly significant positive association (p = 0.000);"communication" and "academic attainment" had significant positive associations (p = 0.033 and 0.024, respectively) with VBD acceptance in the students cohort, while these predictors were insignificant in the teachers community. Women were more likely to receive a third dose of the vaccine (OR = 1.4 vs. 0.9 between teacher and student model); however, no significant association between gender and booster vaccine acceptance was found in a comparative Chi-squared model. Therefore, statistically, the booster vaccine-hesitant risky group was not found to implicate the massive booster vaccine drive among the university academic community. CONCLUSIONS: COVID-19 booster vaccine acceptability among the student cohort was slightly lower than pre-roll-out intent. The teacher community was more inclined to get booster vaccinated. Moreover, differences were found between the multi-dimensional potential factors associated with VBD acceptance among teachers and students in university settings. This study explicitly confirmed positive attitudes toward the safety, health benefits, and variants control of the COVID-19 VBD under any circumstances. Post-vaccination side effect concern was found to be a barrier to administering booster shots and a reason for booster skepticism. Tailored communication and health education interventions need to be adopted to improve the public awareness of booster vaccine consequences, and limit booster skepticism.

Zn3Sb4O6F6 and KI-Doped Zn3Sb4O6F6: A Metal Oxyfluoride System for Photocatalytic Activity, Knoevenagel Condensation, and Bacterial Disinfection.

Zn3Sb4O6F6 crystallites were synthesized by a pH-regulated hydrothermal synthetic approach, while doping on Zn3Sb4O6F6 by KI was performed by the "incipient wetness impregnation technique." The effect of KI in Zn3Sb4O6F6 is found with the changes in morphology in the doped compound, i.e., needle-shaped particles with respect to the irregular cuboid and granular shaped in the pure compound. Closer inspection of the powder diffraction pattern of doped compounds also reveals the shifting of Braggs' peaks toward a lower angle and the difference in cell parameters compared to the pure compound. Both metal oxyfluoride comprising lone pair elements and their doped compounds have been successfully applied as photocatalysts for methylene blue dye degradation. Knoevenagel condensation reactions were performed using Zn3Sb4O6F6 as the catalyst and confirmed 99% yield even at 60 °C temperature under solvent-free conditions. Both pure and KI-doped compounds were tested against several standard bacterial strains, i.e., Enterobacter sp., Escherichia coli, Staphylococcus sp., Salmonella sp., Bacillus sp., Proteous sp., Pseudomonas sp., and Klebsiella sp. by the "disk diffusion method" and their antimicrobial activities were confirmed.

Potential determinants of childhood COVID-19 vaccine confidence among the primary school's stakeholders in Bangladesh: A cross-sectional study to assess the effects of education.

BACKGROUND: Rapid corona virus disease 2019 (COVID-19) vaccination drives aimed to immunize primary school-aged youth have a potential for health safety and supportive academic attainment. This study aimed to identify the potential factors influencing childhood COVID-19 vaccine confidence among the primary school's stakeholders in Bangladesh and assess the effects of health education on vaccine confidence and receptivity. MATERIALS AND METHODS: This cross-sectional study used a bilingual, multi-item, closed-ended, anonymous questionnaire adopted from the extant literature studies on the topic. Data were collected purposively by the face-to-face interview approach. In total, 627 primary school's stakeholders participated in this study. The binary logistic regressions and Chi-square tests were employed to investigate and rationalize the study-outlined objectives where <0.05 was considered statistically significant. RESULTS: The pooled childhood vaccine confidence and receptivity against COVID-19 was 91% (95% CI 89-93) among the primary school's stakeholders. The regression analysis revealed that of eight potential determinants of vaccine confidence, "safety" and "effectiveness" had a highly significant (P = 0.006, P = 0.001, respectively) and positive association and "efficacy" had a significant (P = 0.03) and positive association, while "rumor" had a highly significant (P = 0.000) and negative association with childhood vaccine confidence. The analysis also showed that"health education" had a significant (P = 0.04) and positive association with childhood vaccine confidence and receptivity against COVID-19. Although the odds ratio for receiving childhood vaccine was found to be 0.6, the result was insignificant (P > 0.05) in the Chi-squared test. Hence, there was no vaccine-hesitant risky recipient group identified in implementing upcoming childhood COVID-19 vaccination programs. CONCLUSIONS: This study confirms the importance of a positive perception of vaccine safety, efficacy, effectiveness, and health education for vaccine confidence under any circumstances. Childhood COVID-19 vaccine confidence is Improved if vaccination data become more available to the guardians and school community. Public health education would be considered a preferred approach for building trust and fostering childhood vaccine confidence against COVID-19 in Bangladesh.

Potential factors influencing COVID-19 vaccine acceptance and hesitancy among university students in Bangladesh: a cross-sectional comparative study.

This study investigated Coronavirus disease 2019 (COVID-19) vaccine acceptance, and compared the potential factors influencing vaccine acceptance and hesitancy between public university (PuU) and private university (PrU) students in Bangladesh. An anonymous, self-administered questionnaire was sent to 640 PuU and 660 PrU students in Google Form between 25th September and 22nd November 2021, which resulted in the participation of 1034 (461 PuU vs. 573 PrU) respondents (response rate: 72.03% vs. 86.81%). The pooled vaccine acceptance rates among PuU and PrU students were almost similar (88.1%, 95% confidence interval (CI) 85.1-91.1 vs. 87.6%, 95% CI 84.6-90.6). Employing binary logistic regression to assess the association between various potential factors and vaccine acceptance, the study revealed that out of 10 predictors, 'safety' and 'efficacy' had highly significant positive associations with vaccine acceptance in both cohorts (P = 0.000, P = 0.005). 'Political roles' was found to have varied effects- a significant (P = 0.02) negative and a significant positive (P = 0.002) association with vaccine acceptance in PuU and PrU students, respectively. Additionally, 'communication' (P = 0.003) and 'trust' (P = 0.01) were found to have significant positive associations in PrU students while 'rumours' (P = 0.03) had negative association in PuU students. The odds of accepting the COVID-19 vaccine were 1.5 vs. 0.9 in PuU and PrU students. Although chi-square analysis did not show any significant association between gender and vaccine acceptance, discrepancies were found in the factors that potentially affect vaccine uptake decision between PuU and PrU students. COVID-19 vaccine uptake may be improved if vaccine-related information becomes available and is communicated to large numbers of people effectively. The implementation of multidisciplinary interventional educational programmes may also be considered as a preferred approach to improve student's engagement in pandemic awareness and vaccine readiness.

Potential factors influencing COVID-19 vaccine acceptance and hesitancy: A systematic review.

BACKGROUND AND AIMS: Although vaccines are considered the most effective and fundamental therapeutic tools for consistently preventing the COVID-19 disease, worldwide vaccine hesitancy has become a widespread public health issue for successful immunization. The aim of this review was to identify an up-to-date and concise assessment of potential factors influencing COVID-19 vaccine acceptance and refusal intention, and to outline the key message in order to organize these factors according to country count. METHODS: A systematic search of the peer-reviewed literature articles indexed in reputable databases, mainly Pub Med (MEDLINE), Elsevier, Science Direct, and Scopus, was performed between21stJune 2021 and10th July 2021. After obtaining the results via careful screening using a PRISMA flow diagram, 47 peer-reviewed articles met the inclusion criteria and formed the basic structure of the review. RESULTS: In total, 11 potential factors were identified, of which the greatest number of articles (n = 28) reported "safety" (34.46%; 95% CI 25.05─43.87) as the overarching consideration, while "side effects" (38.73%; 95% CI 28.14─49.32) was reported by 22 articles, which was the next common factor. Other potential factors such as "effectiveness" were identified in 19 articles (29.98%; 95% CI 17.09─41.67), followed by "trust" (n = 15 studies; 27.91%; 95% CI 17.1─38.73),"information sufficiency"(n = 12; 34.46%; 95% CI 35.87─63.07),"efficacy"(n = 8; 28.73%; 95% CI 9.72─47.74), "conspiracy beliefs" (n = 8; 14.30%; 95% CI 7.97─20.63),"social influence" (n = 6; 42.11%; 95% CI 14.01─70.21), "political roles" (n = 4; 16.75%; 95% CI 5.34─28.16), "vaccine mandated" (n = 4; 51.20%; 95% CI 20.25─82.15), and "fear and anxiety" (n = 3; 8.73%; 95% CI 0.59─18.05). The findings for country-specific influential vaccination factors revealed that, "safety" was recognized mostly (n = 14) in Asian continents (32.45%; 95% CI 19.60─45.31), followed by the United States (n = 6; 33.33%; 95% CI12.68─53.98). "Side effects" was identified from studies in Asia and Europe (n = 6; 35.78%; 95% CI 16.79─54.77 and 16.93%; 95% CI 4.70─28.08, respectively), followed by Africa (n = 4; 74.60%, 95% CI 58.08─91.11); however, public response to "effectiveness" was found in the greatest (n = 7) number of studies in Asian countries (44.84%; 95% CI 25─64.68), followed by the United States (n = 6; 16.68%, 95% CI 8.47─24.89). In Europe, "trust" (n = 5) appeared as a critical predictor (24.94%; 95% CI 2.32─47.56). "Information sufficiency" was identified mostly (n = 4) in articles from the United States (51.53%; 95% CI = 14.12─88.74), followed by Asia (n = 3; 40%; 95% CI 27.01─52.99). More concerns was observed relating to "efficacy" and "conspiracy beliefs" in Asian countries (n = 3; 27.03%; 95% CI 10.35─43.71 and 18.55%; 95% CI 8.67─28.43, respectively). The impact of "social influence" on making a rapid vaccination decision was high in Europe (n = 3; 23.85%, 95% CI -18.48─66.18), followed by the United States (n = 2; 74.85%). Finally, "political roles" and "vaccine-mandated" were important concerns in the United States. CONCLUSIONS: The prevailing factors responsible for COVID-19 vaccine acceptance and hesitancy varied globally; however, the global COVID-19 vaccine acceptance relies on several common factors related to psychological and, societal aspect, and the vaccine itself. People would connect with informative and effective messaging that clarifies the safety, side effects, and effectiveness of prospective COVID-19 vaccines, which would foster vaccine confidence and encourage people to be vaccinated willingly.

Evaluation of Leea rubra Leaf Extract for Oxidative Damage Protection and Antitumor and Antimicrobial Potential.

BACKGROUND: The leaves of Leea rubra contain an abundance of phenolic constituents and have medicinal uses as antipyretic and diaphoretic agents and are also used in the treatment of stomach ache, rheumatism, arthritis etc. In spite of the traditional uses, data on the scientific evaluation of the plant are not sufficient. So, the present study was designed to evaluate the protective role of the extract against oxidative damage to DNA and human erythrocytes as well as antitumor and antibacterial activities against some resistant bacteria. METHODS: The protective activity of the ethyl acetate fraction (EAF) of the extract was investigated by evaluating the inhibition of oxidative damage of pUC19 plasmid DNA as well as hemolysis and lipid peroxidation damage to human erythrocytes induced by 2,2'-azobis-2-amidinopropane (AAPH). Antitumor activity was assessed by evaluating the percentage inhibition of cell growth, morphological changes of Ehrlich's ascites carcinoma (EAC) cells, and hematological parameters. Antimicrobial activity was determined by the disc diffusion method against different resistant microorganisms. RESULTS: EAF effectively inhibited AAPH-induced oxidative damage to DNA because it can inhibit the transformation of the supercoiled form of plasmid DNA to open circular and further linear form. The oxidative hemolysis caused by AAPH in human erythrocytes was inhibited by EAF extract in a time-dependent manner, and the production of malondialdehyde (MDA) was significantly reduced, which indicates the prevention of lipid peroxidation. In antitumor assay, 76% growth of inhibition of EAC was observed compared with the control mice (p < 0.05) at a dose of 100 mg/kg body weight. Antimicrobial activity was evaluated against two pathogenic resistant microorganisms (Escherichia coli and Pseudomonas aeruginosa), and the highest antimicrobial activity was observed against Pseudomonas spp. CONCLUSION: EAF may have great importance in preventing oxidative damage to DNA, erythrocytes, and other cellular components as well as can be a good candidate in cancer chemotherapy and treating infectious diseases caused by antibiotic-resistant bacteria.

Characterization of zinc solubilization potential of arsenic tolerant Burkholderia spp. isolated from rice rhizospheric soil.

In this study, experiments were conducted to isolate, characterize, and evaluate rice rhizosphere bacteria for their arsenic (As) tolerance ability and zinc (Zn) solubilization potential in culture media and soil. Among 20 bacterial isolates recovered, six were found to solubilize inorganic Zn salt(s) efficiently under in vitro culture conditions. 16S rRNA gene sequence-based phylogenetic analysis indicated the affiliation of efficient Zn solubilizing bacteria (ZSB) to Burkholderia vietnamiensis and Burkholderia seminalis. Zinc solubilizing efficiency (ZSE) of the bacteria varied with the concentrations and types of Zn salts used in the experiments. Increasing trend in ZSE of the bacteria was noticed when the percentage of ZnO increased from 0.1 to 0.5 but the same decreased at 1.0%. Increased Zn solubilization was noticed when bacteria were incubated with lower concentration of Zn3(PO4)2 and ZnCO3. In general, Zn solubilization increased with increasing incubation time in lower volume medium, while some isolates failed to solubilize one or more tested Zn salts. However, enriched concentrated cells of the ZSB in glucose amended medium with 0.5% ZnO showed an increasing trend of Zn solubilization with time and were able to solubilize more than 300 mg/L Zn. This increased rate of Zn release by the ZSB was attributed to marked decline in pH that might be due to the enhanced gluconic acid production from glucose. As evident from the decreased ZSE of the bacteria in the presence of As(V) in particular, it seems arsenic imparts a negative effect on Zn solubilization. The ZSB were also able to increase the rate of Zn release in soil. A microcosm-based soil incubation study amending the enriched bacteria and 0.5% ZnO in soil showed an elevated level of both water-soluble and available Zn compared to un-inoculated control. During Zn solubilization in microcosms, viable cells in terms of colony-forming unit (CFU) declined by the same order of magnitude both in the presence and absence of ZnO that might be due to the nutrients limiting condition aroused during the incubation period rather than Zn toxicity. The bacteria in this study also exhibited plant growth promoting traits, such as growth in nitrogen-free medium, production of indole acetic acid (IAA), and solubilization of potassium and phosphate. Our findings suggested that Burkholderia spp. could be the potential candidates for enhancing Zn dissolution in the soil that might reduce the rate of inorganic Zn fertilization in agricultural soil.

Characterization of arsenic oxidation and uranium bioremediation potential of arsenic resistant bacteria isolated from uranium ore.

Arsenic (As) is often found naturally as the co-contaminant in the uranium (U)-contaminated area, obstructing the bioremediation process. Although the U-contaminated environment harbors microorganisms capable of interacting with U which could be exploited in bioremediation. However, they might be unable to perform with their full potential due to As toxicity. Therefore, potential in arsenic resistance and oxidation is greatly desired among the microorganisms for a continued bioremediation process. In this study, arsenic-resistant bacteria were isolated from U ore collected from Bundugurang U mine, characterized and their As oxidation and U removal potentials were determined. 16S rRNA gene sequencing and phylogenetic analysis showed the affiliation of isolated bacteria with Microbacterium, Micrococcus, Shinella, and Bacillus. Except Bacillus sp. EIKU7, Microbacterium sp. EIKU5, Shinella sp. EIKU6, and Micrococcus sp. EIKU8 were found to resist more than 400 mM As(V); however, all the isolates could survive in 8 mM As(III). The isolates were found to readily oxidize As under different culture conditions and are also resistant towards Cd, Cr, Co, Ni, and Zn. All the isolates could remove more than 350 mg U/g dry cells within 48 h which were found to be highly dependent upon the concentration of U, biomass added initially, and on the time of exposure. Ability of the isolates to grow in nitrogen-free medium indicated that they can flourish in the nutrition deprived environment. Therefore, the recovery of isolates with the potent ability to resist and oxidize As from U ore might play an important role in toxic metal bioremediation including U.

Elevated level of arsenic negatively influences nifH gene expression of isolated soil bacteria in culture condition as well as soil system.

Comprehensive studies on the effect of arsenic (As) on free-living diazotrophs that play a crucial role in soil fertility by nitrogen fixation are still scanty. Here, we isolated three free-living bacteria from rice field with potential nitrogen-fixing ability and investigated the impact of As on their nifH gene expression and extracellular polysaccharide (EPS) production in culture condition and soil system. 16S rRNA sequence analysis showed that the isolated bacteria were affiliated to ß-Proteobacteria, γ-Proteobacteria and Firmicutes. As(III) exposure to bacterial isolates followed by RT-qPCR analysis revealed that elevated levels of As reduced the expression of nifH gene in selective bacteria, both in culture medium and soil condition. We also noticed reduced production of EPS under higher concentration of As. All the three bacteria showed high tolerance to As(III), able to oxidize As and exhibited significant plant growth-promoting traits. This investigation indicated that an environment exposed with higher concentration of As might perturbed the activity of free-living diazotrophs in agricultural soil system.

Effect of reserpine on Pseudomonas aeruginosa quorum sensing mediated virulence factors and biofilm formation.

This study aimed to evaluate the effect of reserpine, a plant-derived indole-alkaloid, against Pseudomonas aeruginosa PAO1 biofilms. The anti-biofilm activity of reserpine was evaluated by crystal violet staining, MTT assay, confocal laser scanning microscopy and scanning electron microscopy. Reserpine effects were also assessed by qRT-PCR of quorum sensing (QS)-regulated genes and biochemical quantification of the QS-mediated virulence factors pyocyanin, rhamnolipids, proteases and elastases. Reserpine reduced biofilm formation, cell motility, virulence factor production, and QS-controlled gene expression. Additionally, molecular docking analysis for AHL synthase LasI and QS transcriptional regulators LasR/MvfR revealed a plausible molecular mechanisms of reserpine QS inhibition. These findings provide insights into the underlying mode of action of reserpine, which may be useful in the development of new drugs against biofilm-related infections.

Temporal dynamics of total and free-living nitrogen-fixing bacterial community abundance and structure in soil with and without history of arsenic contamination during a rice growing season.

Despite the fact that the nitrogen (N) fixers act as the key regulator of ecosystem process, a detailed study of their abundance, diversity, and dynamics in arsenic (As)-contaminated rice fields is missing so far. DNA extracted from soil followed by 16S rRNA and nifH gene-based real-time qPCR, clone library analysis, and DNA sequencing were used to examine the status of the total and diazotrophic communities in two agricultural fields with and without arsenic contamination history during one rice cultivation season. In general, higher nifH and 16S rRNA gene copy numbers were observed in rice growing soils with lesser As than that with higher As. Elevated levels of 16S rRNA and nifH genes in soil is directly associated with total and nitrogen fixers abundance in the agricultural land without As contamination history through the cultivation period, but the copy number of 16S rRNA gene was decreased, and the nifH gene remained unchanged in the As-contaminated land. Additionally, Canonical Correspondence Analysis (CCA) indicated the possible suppression of nifH gene abundance by soil pH, phosphate, and As content. Increased abundance of total and Acidobacterial lineages in low As-containing soil and the detection of several uncultured groups among nifH gene sequence in higher frequency indicated the presence of novel nifH bearing bacterial groups. Conversely, the abundance of copiotrophic Proteobacterial lineages gradually increased in soil with higher As. Herein, our study demonstrated that the dynamics of free-living nitrogen-fixing bacterial communities were perturbed due to As contamination in agricultural land.

Effect of Bacoside A on growth and biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa.

The goal of this study was to evaluate the antibiofilm and antimicrobial activities of Bacoside A, a formulation of phytochemicals from Bacopa monnieri, against Staphylococcus aureus and Pseudomonas aeruginosa, which are known to form biofilms as one of their virulence traits. The antimicrobial effects of Bacoside A were tested using the minimum inhibitory concentration and minimum bactericidal concentration assays. A cell membrane disruption assay was performed to find its possible target site. MTT assay, crystal violet assay, and microscopic studies were performed to assess the antibiofilm activity. Bacoside A showed antimicrobial activity against both test organisms in their planktonic and biofilm states. At a subminimum inhibitory concentration of 200 µg·mL-1, Bacoside A significantly removed ∼88%-93% of bacterial biofilm developed on microtiter plates. Biochemical and microscopic studies suggested that the eradication of biofilm might be due to the loss of extracellular polymeric substances and to a change in cell membrane integrity of the selected bacterial strains treated with Bacoside A. These results indicate that Bacoside A might be considered as an antimicrobial having the ability to disrupt biofilms. Thus, either alone or in combination with other therapeutics, Bacoside A could be useful to treat biofilm-related infections caused by opportunistic bacterial pathogens.

Hexavalent Chromium Reduction by Microbacterium oleivorans A1: A Possible Mechanism of Chromate -Detoxification and -Bioremediation.

BACKGROUND: Hexavalent chromium (Cr(6+)) contamination is one of the mejor problems of environmental protection for its carcinogenic effect on human health. Remediation of Cr(6+) contaminated environment thus becomes highest priority. METHODS: A Gram positive tiny rod shaped chromate (Cr(6+)) reducing bacterium strain A1 was isolated from uranium ore collected from Jaduguda, East Singhbhum, Jharkhand. The strain was identified and characterized in terms of its potential to reduce more toxic Cr(6+) to its less toxic form for its application in bioremediation of Cr(6+) contaminated environments. RESULTS: 16S rRNA gene based phylogentic analysis identified the strain as Microbacterium oleivorans. Along with Cr(6+), the strain showed resistance to other heavy metals including Ag, Cu, Co, Hg, Ni and Zn also. Complete reduction of Cr(6+) (750 µM) was achieved within 84 h with optimum reduction at pH 9 and 30°C. Effect of different parameters including cell mass concentration, pH, induction with Cr(6+), SO4 = ion, heavy metals, etc. on Cr(6+) reduction were studied thoroughly at resting cell condition to study its potential towards Cr(6+) bioremediation. Chromate reductase gene (chrA) was detected within this strain. CONCLUSION: Along with presence of appropriate genetic determinant, efficient Cr(6+) reduction ability of the strain indicated its potential for developing redox based Cr(6+) remediation system for varied concentrations of Cr6+ under a wide range of environmental conditions. Patent data have suggested the efficient application of Cr(6+) reducing bacteria in cleaning up of Cr(6+) contaminated environments.

Diversity, metal resistance and uranium sequestration abilities of bacteria from uranium ore deposit in deep earth stratum.

Metal resistance and uranium (U) sequestration abilities of bacteria residing in subsurface U ore was investigated using 122 pure culture strains isolated through enrichment. The cumulative frequencies of isolates resistant to each metal tested were as follows: As(V), 74%; Zn, 58%; Ni, 53%; Cd, 47%; Cr(VI), 41%; Co, 40%; Cu, 20%; and Hg, 4%. 16S rRNA gene analysis revealed that isolated bacteria belonged to 14 genera with abundance of Arthrobacter, Microbacterium, Acinetobacter and Stenotrophomonas. Cobalt did not interfere with the growth of most of the bacterial isolates belonging to different groups while U allowed growth of four different genera of which Stenotrophomonas and Microbacterium showed high U tolerance. Interestingly, tolerance to Ni, Zn, Cu, and Hg was observed only in Microbacterium, Arthrobacter, Paenibacillus¸ and Acinetobacter, respectively. However, Microbacterium was found to be dominant when isolated from other five different metal enrichments including U. Uranium removal study showed that 84% of the test bacteria could remove more than 50mgUg(-1) dry weight from 80 or 160mgL(-1) U within 48h. In general, Microbacterium, Arthrobacter and Acinetobacter could remove a higher amount of U. High resolution transmission electron microscopy (HRTEM) study of U exposed cells revealed that accumulated U sequestered mostly around the cell periphery. The study highlights that indigenous U ore deposit bacteria have the potential to interact with U, and thus could be applied for bioremediation of U contaminated sites or wastes.

Analgesic, antibacterial and central nervous system depressant activities of Albizia procera leaves

Objective: To ascertain analgesic, antibacterial and central nervous system (CNS) depressant activities of ethyl acetate, dichloromethane and carbon tetrachloride fractions of methanol extract of Albizia procera (A. procera) leaves. Methods: Leaves extracts of A. procera were tested for analgesic activity by acetic acid induced and formalin test method in mice. The in vitro antibacterial activity was performed by agar well diffusion method. CNS depressant activity was evaluated by hole cross and open field tests. Results: All the extracts at 200 mg/kg exhibited significant (P Conclusions: It is concluded that all the extracts possess potential analgesic and CNS depressants activity. This study also showed that different fractions of methanol extract could be potential sources of new antimicrobial agents.

Antibacterial, antidiarrhoeal, and cytotoxic activities of methanol extract and its fractions of Caesalpinia bonducella (L.) Roxb leaves.

BACKGROUND: Caesalpinia bonducella is an important medicinal plant for its traditional uses against different types of diseases. Therefore, the present study investigated the antimicrobial, antidiarrhoeal, and cytotoxic activities of the methanol extract and ethyl acetate, chloroform, and petroleum ether (pet. ether) fractions of C. bonducella leaves. METHODS: The antibacterial potentialities of methanol extract and its fractions of C. bonducella leaves were investigated by the disc diffusion method against four gram-positive and five gram-negative bacteria at 300, 500 and 800 µg/disc. Kanamycin (30 µg/disc) was used as the standard drug. Antidiarrhoeal activities of leaf extracts were evaluated at two doses (200 and 400 mg/kg) and compared with loperamide in a castor oil-induced diarrhoeal model in rat. The fractions were subjected to a brine shrimp lethality test to evaluate their cytotoxicity. RESULTS: The methanol extract and other three fractions exhibited better activities at higher concentrations. Amongst, the chloroform fraction showed maximum activity at all three concentrations (300, 500, and 800 µg/disc) against almost all bacteria. S. aureus and P. aeruginosa showed better sensitivities to all extracts at all three concentrations excluding the pet. ether fraction. Bacillus megaterium and Klebsiella spp. were two bacteria amongst nine that showed lowest sensitivity to the extracts. Maximum zone of inhibition (25-mm) was obtained by the methanol extract at an 800 µg/disc concentration against S. aureus. In the antidiarrhoeal test, all fractions exhibited dose-dependent actions, which were statistically significant (p < 0.05). Ethyl acetate fraction exerted maximum inhibition (51.11%) against defecation, whereas 57.75% inhibition was obtained for loperamide. Moderate cytotoxicity was found for the methanol extract and its three fractions compared with the standard drug vincristine sulfate in the brine shrimp bioassay. In the present study, the LC50 values of the methanol crude extract and ethyl acetate, chloroform, pet. ether fractions and vincristine sulfate were 223.87, 281.84, 112.2, 199.53, and 12.59 µg/mL, respectively. Therefore, the ethyl acetate fraction showed maximum cytotoxicity, whereas minimum cytotoxicity was observed for the chloroform fraction. CONCLUSION: The present study revealed that the ethyl acetate fraction of the C. bonducella leaves has significant antidiarrhoeal properties. The methanol extract and other three fractions of the C. bonducella leaves possess potent antibacterial activities along with moderate cytotoxicities that may lead to new drug development.

Estimation of total phenol and in vitro antioxidant activity of Albizia procera leaves.

BACKGROUND: Research on natural products has gained a wide popularity due to the potential of discovering active compounds. The antioxidant properties contained in plants have been proposed as one of the mechanisms for the observed beneficial effect. Therefore, the present study investigated the antioxidant activity and total phenolic contents of various solvent extracts of Albizia procera leaves. METHODS: Antioxidant activity of the methanol extract and its derived fractions petroleum ether (APP), carbon tetrachloride (APC), dichloromethane (APD), ethyl acetate (APE), and residual aqueous fraction (APA) of the leaves of Albizia procera was performed by in vitro chemical analyses. Total phenolic content of the APM and other five fractions were also determined. APM and its derived fractions were also subjected to preliminary phytochemical screening test for various constituents. RESULTS: Phytochemical screening revealed the presence of saponins, steroids, tannins, glycosides and flavonoids in the extracts. Amongst the extracts, APE showed the highest total phenolic content (449.18 ± 18.41mg of gallic acid equivalent/g of extract). In DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging test, the IC(50) value of APM, APP, APC, APD, APE and APA was 43.43, 63.60, 166.18, 41.15, 11.79, and 63.06 µg/mL, respectively. Therefore, among the APM and its derived fractions, APE showed the highest antioxidant activity which is comparable to that of standard ascorbic acid (AA) (IC(50) 10.12 µg/mL). The total antioxidant capacity was found to be varied in different fractions. The reducing activity on ferrous ion was ranked as APE > APD > APM > APA > APC. CONCLUSION: The above evidences suggest that APE of A. procera leaf is a potential source of natural antioxidant and can be used to prevent diseases associated with free radicals.

Uranium and other heavy metal resistance and accumulation in bacteria isolated from uranium mine wastes.

Ten bacterial strains isolated from uranium mine wastes were characterized in terms of their uranium and other metal resistance and accumulation. 16S rRNA gene sequence analysis identified the strains as members of genera Bacillus, Serratia, and Arthrobacter. Strains were able to utilize various carbon sources, particularly aromatic hydrocarbons, grow at broad pH and temperature ranges and produce non specific acid phosphatase relevant for metal phosphate precipitation in contaminated environment. The isolates exhibited high uranium and other heavy metals (Ni, Co, Cu and Cd) resistance and accumulation capacities. Particularly, Arthrobacter sp. J001 and Bacillus sp. J003 were superior in terms of U resistance at low pH (pH 4.0) along with metals and actinides (U and Th) removal with maximum cell loading of 1088 µmol U, 1293 µmol Th, 425 µmol Cu, 305 µmol Cd, 377 µmol Zn, 250 µmol Ni g(-1) cell dry wt. Genes encoding P(1B)-type ATPases (Cu-CPx and Zn-CPx) and ABC transporters (nik) as catalytic tools for maintaining cellular metal homeostasis were detected within several Bacillus spp., with possible incidence of horizontal gene transfer for the later gene showing phylogenetic lineage to α Proteobacteria members. The study provides evidence on intrinsic abilities of indigenous bacteria from U-mine suitable for survival and cleaning up of contaminated mine sites.