Production and optimization of surfactin produced from locally isolated Bacillus halotolerans grown on agro-industrial wastes and its antimicrobial efficiency.

INTRODUCTION: Optimal exploitation of the huge amounts of agro-industrial residuals that are produced annually, which endangers the ecosystem and ultimately contributes to climate change, is one of the solutions available to produce value-added compounds. AIM AND OBJECTIVES: This study aimed at the economic production and optimization of surfactin. Therefore, the production was carried out by the microbial conversion of Potato Peel Waste (PPW) and Frying Oil Waste (FOW) utilizing locally isolated Bacillus halotolerans. Also, investigating its potential application as an antimicrobial agent towards some pathogenic strains. RESULTS: Screening the bacterial isolates for surfactin production revealed that the strain with the highest yield (49 g/100 g substrate) and efficient oil displacement activity was genetically identified as B. halotolerans. The production process was then optimized utilizing Central Composite Design (CCD) resulting in the amelioration of yield by 11.4% (from 49 to 55.3 g/100 g substrate) and surface tension (ST) by 8.3% (from 36 to 33 mN/m) with a constant level of the critical micelle concentration (CMC) at 125 mg/L. Moreover, the physiochemical characterization studies of the produced surfactin by FTIR, 1H NMR, and LC-MS/MS proved the existence of a cyclic lipopeptide (surfactin). The investigations further showed a strong emulsification affinity for soybean and motor oil (E24 = 50%), as well as the ability to maintain the emulsion stable over a wide pH (4-10) and temperature (10-100 °C) range. Interestingly, surfactin had a broad-spectrum range of inhibition activity against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, klebsiella pneumonia, and Candida albicans. CONCLUSION: Subsequently, the screening of the isolates and the utilized food-processing wastes along with the extraction technique resulted in a high yield of surfactin characterized by acceptable ST and CMC levels. However, optimization of the cultural conditions to improve the activity and productivity was achieved using Factor-At-A-Time (OFAT) and Central Composite Design (CCD). In contrast, surface activity recorded a maximum level of (33 mN/n) and productivity of 55.3 g/100 g substrate. The optimized surfactin had also the ability to maintain the stability of emulsions over a wide range of pH and temperature. Otherwise, the obtained results proved the promising efficiency of the surfactin against bacterial and fungal pathogens.

Isolation and identification of NEAU-CP5: A seed-endophytic strain of B. velezensis that controls tomato bacterial wilt.

Bacterial wilt of tomato caused by Ralstonia solanacearum is a critical soilborne disease that drastically reduces yield. In the current study, an endophytic strain NEAU-CP5 with strong antagonistic activity against R. solanacearum was isolated from tomato seeds and characterized. The strain was identified as Bacillus velezensis based on 16S rRNA gene and whole genome sequence analysis. NEAU-CP5 can secrete amylase, protease, and cellulase, and also produce known antibacterial metabolites, including cyclo (leucylprolyl), cyclo (phenylalanyl-prolyl), cyclo (Pro-Gly), 3-benzyl-2,5-piperazinedione, pentadecanoic acid, eicosane, 2-methyoic acid, isovaleric acid, dibuty phthalate, and esters of fatty acids (HFDU), which may be responsible for its strong antibacterial activity. Fourteen gene clusters associated with antibacterial properties were also identified in the whole genome sequence of NEAU-CP5. Pot experiment demonstrated that the application of 108 CFU/mL NEAU-CP5 on tomato plants significantly reduced the incidence of tomato bacterial wilt by 68.36 ± 1.67 %. NEAU-CP5 also increased the activity of defense-related enzymes (CAT, POD, PPO, SOD, and PAL) in tomato plants. This is the first report of an effective control of bacterial wilt on tomato plants by B. velezensis and highlights the potential of NEAU-CP5 as a potential biocontrol agent for the management of tomato bacterial wilt.

Deciphering the pancreatic cancer microbiome in Mainland China: Impact of Exiguobacterium/Bacillus ratio on tumor progression and prognostic significance.

The existing body of research underscores the critical impact of intratumoral microbiomes on the progression of pancreatic ductal adenocarcinoma (PDAC), particularly in reshaping the tumor microenvironment and influencing gemcitabine resistance. However, peritumoral tissues' microbiome, distinct from PDAC tumors, remain understudied, and Western-centric analyses overlooking potential variations in dietary-influenced microbiomes. Our study addresses this gap by 16 S rRNA sequencing of PDAC tumors and matched peritumoral tissues from Chinese Mainland patients. Our research has uncovered that the microbiome composition within tumors and paired peritumoral tissues exhibits a high degree of similarity, albeit with certain discrepancies. Notably, Exiguobacterium is found to be more abundant within the tumor tissues. Further investigations have revealed that a lower Exiguobacterium/Bacillus ratio in both the tumor and peritumoral tissues of PDAC patients is indicative of a more favorable prognosis. Further exploration utilizing an orthotopic tumor model demonstrates that the probiotic Bacillus Coagulans impedes PDAC progression, accompanied by an increased infiltration of inflammatory neutrophils in tumors. Additionally, in the subgroup with a low Exiguobacterium/Bacillus ratio, whole-exome sequencing reveals elevated missense mutations in ABL2 and MSH2. The elevated expression of ABL2 and MSH2 has been correlated with poorer prognostic outcomes in PDAC patients. Together, these insights shed light on risk factors influencing PDAC progression and unveil potential therapeutic targets, alongside probiotic intervention strategies.

The potential of Bacillus species isolated from Cinnamomum camphora for biofuel production.

BACKGROUND: Increasing concerns about climate change and global petroleum supply draw attention to the urgent need for the development of alternative methods to produce fuels. Consequently, the scientific community must devise novel ways to obtain fuels that are both sustainable and eco-friendly. Bacterial alkanes have numerous potential applications in the industry sector. One significant application is biofuel production, where bacterial alkanes can serve as a sustainable eco-friendly alternative to fossil fuels. This study represents the first report on the production of alkanes by endophytic bacteria. RESULTS: In this study, three Bacillus species, namely Bacillus atrophaeus Camph.1 (OR343176.1), Bacillus spizizenii Camph.2 (OR343177.1), and Bacillus aerophilus Camph.3 (OR343178.1), were isolated from the leaves of C. camphora. The isolates were then screened to determine their ability to produce alkanes in different culture media including nutrient broth (NB), Luria-Bertani (LB) broth, and tryptic soy broth (TSB). Depending on the bacterial isolate and the culture media used, different profiles of alkanes ranging from C8 to C31 were detected. CONCLUSIONS: The endophytic B. atrophaeus Camph.1 (OR343176.1), B. spizizenii Camph.2 (OR343177.1), and B. aerophilus Camph.3 (OR343178.1), associated with C. camphora leaves, represent new eco-friendly approaches for biofuel production, aiming towards a sustainable future. Further research is needed to optimize the fermentation process and scale up alkane production by these bacterial isolates.

Molecular Characterization Reveals Biodiversity and Biopotential of Rhizobacterial Isolates of Bacillus Spp.

Bacillus species appearas the most attractive plant growth-promoting rhizobacteria (PGPR) and alternative to synthetic chemical pesticides. The present study examined the antagonistic potential of spore forming-Bacilli isolated from organic farm soil samples of Allahabad, India. Eighty-seven Bacillus strains were isolated and characterized based on their morphological, plant growth promoting traits and molecular characteristics. The diversity analysis used 16S-rDNA, BOX-element, and enterobacterial repetitive intergenic consensus. Two strains, PR30 and PR32, later identified as Bacillus sp., exhibited potent in vitro antagonistic activity against Ralstonia solanaceorum. These isolates produced copious amounts of multiple PGP traits, such as indole-3-acetic acid (40.0 and 54.5 µg/mL), phosphate solubilization index (PSI) (4.4 and 5.3), ammonia, siderophore (3 and 4 cm), and 1-aminocyclopropane-1-carboxylate deaminase (8.1and 9.2 µM/mg//h) and hydrogen cyanide. These isolates were subjected to the antibiotic sensitivity test. The two potent isolates based on the higher antagonistic and the best plant growth-promoting ability were selected for plant growth-promoting response studies in tomatoe, broccoli, and chickpea. In the pot study, Bacillus subtilis (PR30 and PR31) showed significant improvement in seed germination (27-34%), root length (20-50%), shoot length (20-40%), vigor index (50-75%), carotenoid content (0.543-1.733), and lycopene content (2.333-2.646 mg/100 g) in tomato, broccoli, and chickpea. The present study demonstrated the production of multiple plant growth-promoting traits by the isolates and their potential as effective bioinoculants for plant growth promotion and biocontrol of phytopathogens.

Antagonistic and enzymatic activities of Bacillus species isolated from the fish gastrointestinal tract as potential probiotics use in Artemia culture.

Probiotics have been used successfully in aquaculture to enhance disease resistance, nutrition, and/or growth of cultured organisms. Six strains of Bacillus were isolated from the intestinal tracts of fish and recognised by conventional biochemical traits. The six isolated strains were Bacillus cereus and Bacillus subtilis using MALDI-TOF-MS technique. The probiotic properties of these Bacillus strains were studied. The tested bacillus strains exhibit antibacterial activity against the different pathogens. The strain S5 gave the important inhibition zones against most pathogens (20.5, 20.33, 23, and 21 mm against Vibrio alginolyticus, Vibrio parahaemolyticus, Staphylococcus aureus, and Salmonella typhimurium, respectively). According to our results, all Bacillus strains have extracellular components that can stop pathogenic bacteria from growing. The enzymatic characterization showed that the tested strains can produce several biotechnological enzymes such as α-glucosidase, naphtol-AS-BI-Phosphohydrolase, esterase lipase, acid phosphatase, alkaline phosphatase, amylase, lipase, caseinase, and lecithinase. All Bacillus strains were adhesive to polystyrene. The adding Bacillus strains to the Artemia culture exerted significantly greater effects on the survival of Artemia. The challenge test on Artemia culture showed that the protection against pathogenic Vibrio was improved. These findings allow us to recommend the examined strains as prospective probiotic options for the Artemia culture, which will be used as food additives to improve the culture conditions of crustacean larvae and marine fish.

Isolation and characterization of polyester polyurethane-degrading bacterium Bacillus sp. YXP1.

Microorganisms have the potential to be applied for the degradation or depolymerization of polyurethane (PU) and other plastic waste, which have attracted global attention. The appropriate strain or enzyme that can effectively degrade PU is the key to treat PU plastic wastes by biological methods. Here, a polyester PU-degrading bacterium Bacillus sp. YXP1 was isolated and identified from a plastic landfill. Three PU substrates with increasing structure complexities, including Impranil DLN, poly (1,4-butylene adipate)-based PU (PBA-PU), and polyester PU foam, were used to evaluate the degradation capacity of Bacillus sp. YXP1. Under optimal conditions, strain YXP1 could completely degrade 0.5% Impranil DLN within 7 days. After 30 days, the weight loss of polyester PU foam by strain YXP1 was as high as 42.1%. In addition, PBA-PU was applied for degradation pathway analysis due to its clear composition and chemical structure. Five degradation intermediates of PBA-PU were identified, including 4,4'-methylenedianiline (MDA), 1,4-butanediol, adipic acid, and two MDA derivates, indicating that strain YXP1 could depolymerize PBA-PU by the hydrolysis of ester and urethane bonds. Furthermore, the extracellular enzymes produced by strain YXP1 could hydrolyze PBA-PU to generate MDA. Together, this study provides a potential bacterium for the biological treatment of PU plastic wastes and for the mining of functional enzymes.

Co-inoculation with novel nodule-inhabiting bacteria reduces the benefits of legume-rhizobium symbiosis.

The ecologically and economically vital symbiosis between nitrogen-fixing rhizobia and leguminous plants is often thought of as a bi-partite interaction, yet studies increasingly show the prevalence of non-rhizobial endophytes (NREs) that occupy nodules alongside rhizobia. Yet, what impact these NREs have on plant or rhizobium fitness remains unclear. Here, we investigated four NRE strains found to naturally co-occupy nodules of the legume Medicago truncatula alongside Sinorhizobium meliloti in native soils. Our objectives were to (1) examine the direct and indirect effects of NREs on M. truncatula and S. meliloti fitness, and (2) determine whether NREs can re-colonize root and nodule tissues upon reinoculation. We identified one NRE strain (522) as a novel Paenibacillus species, another strain (717A) as a novel Bacillus species, and the other two (702A and 733B) as novel Pseudomonas species. Additionally, we found that two NREs (Bacillus 717A and Pseudomonas 733B) reduced the fitness benefits obtained from symbiosis for both partners, while the other two (522, 702A) had little effect. Lastly, we found that NREs were able to co-infect host tissues alongside S. meliloti. This study demonstrates that variation of NREs present in natural populations must be considered to better understand legume-rhizobium dynamics in soil communities.

Bacillus licheniformis and Bacillus velezensis from Rhizosphere of Clerodendrum infortunatum L. Promote Plant Growth and Resistance to Sclerotium rolfsii in Vigna unguiculata (L.) Walp.

In the current study, thirty bacterial strains isolated from the rhizosphere of Clerodendrum infortunatum L. were evaluated for the properties related to the plant growth promotion and disease resistance. Here, all the selected strains were screened for its antagonistic effect towards the phytopathogen Sclerotium rolfsii and also for the production of bioactive compounds known to promote the plant growth. Among these isolates, CiRb1 and CiRb16 were observed to have a broad range of plant beneficial features and were identified as Bacillus licheniformis and Bacillus velezensis respectively. Both the isolates were also demonstrated to produce the volatile organic compounds (VOCs) responsible for the growth enhancement in Brassica nigra (L.) and growth inhibition of S. rolfsii. Talc based formulations made out of both B. licheniformis and B. velezensis were further demonstrated to augment the plant growth and protection against S. rolfsii in Vigna unguiculata (L.) Walp. By the GC-MS based analysis, undecane could also be detected in the methanolic extracts prepared from both B. licheniformis and B. velezensis. Here, the selected rhizobacterial isolates were found to promote the plant growth and disease resistance through both direct and VOC mediated mechanisms. The results of the study hence reveal both B. licheniformis and B. velezensis have the potential in field application to promote the growth and control of plant diseases.

Isolation and characterization of bio-prospecting gut strains Bacillus safensis CGK192 and Bacillus australimaris CGK221 for plastic (HDPE) degradation.

The present work reports the application of novel gut strains Bacillus safensis CGK192 (Accession No. OM658336) and Bacillus australimaris CGK221 (Accession No. OM658338) in the biological degradation of synthetic polymer i.e., high-density polyethylene (HDPE). The biodegradation assay based on polymer weight loss was conducted under laboratory conditions for a period of 90 days along with regular evaluation of bacterial biomass in terms of total protein content and viable cells (CFU/cm2). Notably, both strains achieved significant weight reduction for HDPE films without any physical or chemical pretreatment in comparison to control. Hydrophobicity and biosurfactant characterization were also done in order to assess strains ability to form bacterial biofilm over the polymer surface. The post-degradation characterization of HDPE was also performed to confirm degradation using analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electronic microscopy (FE-SEM) coupled with energy dispersive X-ray (EDX), and Gas chromatography-mass spectrometry (GC-MS). Interestingly strain CGK221 was found to be more efficient in forming biofilm over polymer surface as indicated by lower half-life (i.e., 0.00032 day-1) and higher carbonyl index in comparison to strain CGK192. The findings reflect the ability of our strains to develop biofilm and introduce an oxygenic functional group into the polymer surface, thereby making it more susceptible to degradation.

Bioactivities evaluation of an endophytic bacterial strain Bacillus tequilensis QNF2 inhibiting apple ring rot caused by Botryosphaeria dothidea on postharvest apple fruits.

Apple ring rot, one of the most common apple postharvest diseases during storage, is caused by Botryosphaeria dothidea. Presently, the disease management is primarily dependent on chemical fungicide application. Here we demonstrated an endophyte bacterium Bacillus tequilensis QNF2, isolated from Chinese leek (Allium tuberosum) roots considerably suppressed B. dothidea mycelial growth, with the highest suppression of 73.56 % and 99.5 % in the PDA and PDB medium, respectively in vitro confront experiments. In in vivo experiments, B. tequilensis QNF2 exhibited a control efficacy of 88.52 % and 100 % on ring rot disease on postharvest apple fruits inoculated with B. dothidea disc and dipped into B. dothidea culture, respectively. In addition, B. tequilensis QNF2 volatile organic compounds (VOCs) also manifested markedly inhibition against B. dothidea mycelial growth and the ring rot on postharvest apple fruits. Moreover, B. tequilensis QNF2 severely damaged the mycelial morphology of B. dothidea. Finally, B. tequilensis QNF2 significantly repressed the expression of six pathogenicity-related genes, such as adh, aldh, aldh3, galm, pdc1, pdc2, involved in glycolysis/gluconeogenesis of B. dothidea. The findings of the study proved that B. tequilensis QNF2 was a promising alternative for controlling apple ring rot of postharvest apple fruit.

Bioprospecting of extremophilic perchlorate-reducing bacteria: report of promising Bacillus spp. isolated from sediments of the bay of Cartagena, Colombia.

Three extremophile bacterial strains (BBCOL-009, BBCOL-014 and BBCOL-015), capable of degrading high concentrations of perchlorate at a range of pH (6.5 to 10.0), were isolated from Colombian Caribbean Coast sediments. Morphological features included Gram negative strain bacilli with sizes averaged of 1.75 × 0.95, 2.32 × 0.65 and 3.08 × 0.70 µm, respectively. The reported strains tolerate a wide range of pH (6.5 to 10.0); concentrations of NaCl (3.5 to 7.5% w/v) and KClO4- (250 to 10000 mg/L), reduction of KClO4- from 10 to 25%. LB broth with NaCl (3.5-30% w/v) and KClO4- (250-10000 mg/L) were used in independent trials to evaluate susceptibility to salinity and perchlorate, respectively. Isolates increased their biomass at 7.5 % (w/v) NaCl with optimal development at 3.5 % NaCl. Subsequently, ClO4- reduction was assessed using LB medium with 3.5% NaCl and 10000 mg/L ClO4-. BBCOL-009, BBCOL-014 and BBCOL-015 achieved 10%, 17%, and 25% reduction of ClO4-, respectively. The 16 S rRNA gene sequence grouped them as Bacillus flexus T6186-2, Bacillus marisflavi TF-11 (T), and Bacillus vietnamensis 15 - 1 (T) respectively, with < 97.5% homology. In addition, antimicrobial resistance to ertapenem, vancomycine, amoxicillin clavulanate, penicillin, and erythromycin was present in all the isolates, indicating their high adaptability to stressful environments. The isolated strains from marine sediments in Cartagena Bay, Colombia are suitable candidates to reduce perchlorate contamination in different environments. Although the primary focus of the study of perchlorate-reducing and resistant bacteria is in the ecological and agricultural realms, from an astrobiological perspective, perchlorate-resistant bacteria serve as models for astrobiological investigations.

Fungal and Bacterial Biodeterioration of Outdoor Canvas Paintings: The Case of the Cloisters of Quito, Ecuador.

The historic center of Quito, Ecuador, was one of the first World Cultural Heritage Sites declared by UNESCO in 1978. There are numerous religious buildings built during the Spanish colonial period reflecting the cultural heritage in this area. Between them, the cloisters of San Francisco, Santo Domingo, and Santa Clara should be highlighted. The specific problems of conservation of the outdoor canvas paintings are not well known at the moment. The objective of this paper is to achieve a conservation study of the canvas paintings exhibited in these three cloisters of the historic center of Quito in order to identify the microbial agents and the main bioclimatic parameters of deterioration. For this, a study of the state of conservation of five canvas paintings has been carried out, as well as a sampling and identification of the main microorganisms present on the obverse and reverse of the works, employing diverse techniques, traditional and biomolecular ones. An analysis of climatic conditions has also been achieved in the cloister of San Francisco. The results of the study indicate that the exhibition conditions in the cloisters are really problematic for the conservation of paintings. Important biodeteriorating agents have been isolated, including fungi and bacteria species belonging, among others, to the genera Bacillus, Penicillium, Alternaria, Mucor, and Aspergillus. We have also researched its relationship with the deterioration state of the artworks and the exhibition conditions in each case, proposing guidelines for the proper conservation of this important World Cultural Heritage.

Links among extracellular enzymes, lignin degradation and cell growth establish the models to identify marine lignin-utilizing bacteria.

A major conundrum in the isolation of prokaryotes from open environments is stochasticity. It is especially difficult to study low abundance groups where very little biological information exists, although single-cell genomics and metagenomics have alleviated some of this bottleneck. Here, we report an approach to capture lignin-utilizing bacteria by linking a physical model to actual organisms. Extracellular enzymes, lignin degradation and cell growth are crucial phenotypes of lignin-utilizing bacteria, but their interrelationships remain poorly understood. In this study, the phenotypes of bacteria isolated from in situ lignocellulose enrichment samples in coastal waters were traced and statistically analysed. It suggested cell growth, dye-decolorizing peroxidase (DyP) and reactive oxygen species (ROS) were significantly correlated with lignin degradation, exhibiting a genus-specific property. The established models enabled us to efficiently capture lignin-utilizing bacteria and rapidly evaluate lignin degradation for Bacillus and Vibrio strains. Through the model, we identified several previously unrecognized marine bacterial lignin degraders. Moreover, it demonstrated that the isolated marine lignin-utilizing bacteria employ a DyP-based system and ROS for lignin depolymerization, providing insights into the mechanism of marine bacterial lignin degradation. Our findings should have implications beyond the capture of lignin-utilizing bacteria, in the isolation of other microorganisms with as-yet-unknown molecular biomarkers.

Genome sequencing and identification of cellulase genes in Bacillus paralicheniformis strains from the Red Sea.

BACKGROUND: Cellulolytic microorganisms are considered a key player in the degradation of plant biomass in various environments. These microorganisms can be isolated from various environments, such as soils, the insect gut, the mammalian rumen and oceans. The Red Sea exhibits a unique environment in terms of presenting a high seawater temperature, high salinity, low nutrient levels and high biodiversity. However, there is little information regarding cellulase genes in the Red Sea environment. This study aimed to examine whether the Red Sea can be a resource for the bioprospecting of microbial cellulases by isolating cellulase-producing microorganisms from the Red Sea environment and characterizing cellulase genes. RESULTS: Three bacterial strains were successfully isolated from the plankton fraction and the surface of seagrass. The isolated strains were identified as Bacillus paralicheniformis and showed strong cellulase activity. These results suggested that these three isolates secreted active cellulases. By whole genome sequencing, we found 10 cellulase genes from the three isolates. We compared the expression of these cellulase genes under cellulase-inducing and non-inducing conditions and found that most of the cellulase genes were generally upregulated during cellulolysis in the isolates. Our operon structure analysis also showed that cellulase genes form operons with genes involved in various kinds of cellular reactions, such as protein metabolism, which suggests the existence of crosstalk between cellulolysis and other metabolic pathways in the bacterial isolates. These results suggest that multiple cellulases are playing important roles in cellulolysis. CONCLUSIONS: Our study reports the isolation and characterization of cellulase-producing bacteria from the Red Sea. Our whole-genome sequencing classified our three isolates as Bacillus paralicheniformis, and we revealed the presence of ten cellulase orthologues in each of three isolates' genomes. Our comparative expression analysis also identified that most of the cellulase genes were upregulated under the inducing conditions in general. Although cellulases have been roughly classified into three enzyme groups of beta-glucosidase, endo-ß-1,4-glucanase and exoglucanase, these findings suggest the importance to consider microbial cellulolysis as a more complex reaction with various kinds of cellulase enzymes.

Microbiology of secondary infections in Buruli ulcer lesions; implications for therapeutic interventions.

BACKGROUND: Buruli ulcer (BU) is a skin disease caused by Mycobacterium ulcerans and is the second most common mycobacterial disease after tuberculosis in Ghana and Côte d'Ivoire. M. ulcerans produces mycolactone, an immunosuppressant macrolide toxin, responsible for the characteristic painless nature of the infection. Secondary infection of ulcers before, during and after treatment has been associated with delayed wound healing and resistance to streptomycin and rifampicin. However, not much is known of the bacteria causing these infections as well as antimicrobial drugs for treating the secondary microorganism. This study sought to identify secondary microbial infections in BU lesions and to determine their levels of antibiotic resistance due to the prolonged antibiotic therapy required for Buruli ulcer. RESULTS: Swabs from fifty-one suspected BU cases were sampled in the Amansie Central District from St. Peters Hospital (Jacobu) and through an active case surveillance. Forty of the samples were M. ulcerans (BU) positive. Secondary bacteria were identified in all sampled lesions (N = 51). The predominant bacteria identified in both BU and Non-BU groups were Staphylococci spp and Bacilli spp. The most diverse secondary bacteria were detected among BU patients who were not yet on antibiotic treatment. Fungal species identified were Candida spp, Penicillium spp and Trichodema spp. Selected secondary bacteria isolates were all susceptible to clarithromycin and amikacin among both BU and Non-BU patients. Majority, however, had high resistance to streptomycin. CONCLUSIONS: Microorganisms other than M. ulcerans colonize and proliferate on BU lesions. Secondary microorganisms of BU wounds were mainly Staphylococcus spp, Bacillus spp and Pseudomonas spp. These secondary microorganisms were less predominant in BU patients under treatment compared to those without treatment. The delay in healing that are experienced by some BU patients could be as a result of these bacteria and fungi colonizing and proliferating in BU lesions. Clarithromycin and amikacin are likely suitable drugs for clearance of secondary infection of Buruli ulcer.

Bacillus salipaludis sp. nov., isolated from saline-alkaline soil.

A Gram-staining-positive, endospore-forming, aerobic strain, designed WN066T, was isolated from saline-alkali wetland soil of Tianjin, China. Phylogenetic analysis based on 16S rRNA gene sequence indicated WN066T was a member of the genus of Bacillus, and most closely related to Bacillus drentensis DSM 15600T (98.9%), Bacillus cucumis CCM 8651T (98.8%), Bacillus bataviensis DSM 15601T (98.7%) and Bacillus niacini DSM 2923T (98.7%). However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (DDH) values between strain WN066T and the most closely related species were less than the previously proposed cutoff values for differentiating species within the genus, suggesting that this strain represented a novel Bacillus species. The strain grew at 19-42 °C (optimally 33-37 °C) in the presence of 3-20% (w/v) NaCl (optimally 8-12%(w/v)), and at pH 6.5-11.0 (optimally 7.5-8.5). The major cellular fatty acids were iso-C15:0 (24.8%) and anteiso-C15:0 (38.9%). The predominant polar lipids consisted of diphosphatidylglycerol (DPG), phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). The size of the draft genome was 6,213,503 bp in size and had a G + C content of 38.6 mol %. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. On basis of phenotypic, phylogenetic, chemotaxonomic and genomic features, strain WN066T represented a novel species within the genus Bacillus, for which the name B. salipaludis sp. nov. is proposed. The type strain is WN066T (= KCTC 33953T = ACCC 60085T).

Prevalence of bacterial contamination of touchscreens and posterior surfaces of smartphones owned by healthcare workers: a cross-sectional study.

BACKGROUND: Mobile phones used by healthcare workers (HCWs) are contaminated with bacteria, but the posterior surface of smartphones has rarely been studied. The aim of this study was to compare the prevalence of microbial contamination of touchscreens and posterior surfaces of smartphones owned by HCWs. METHODS: A cross-sectional study of smartphones used by HCWs employed at two intensive care units at a Japanese tertiary care hospital was performed. Bacteria on each surface of the smartphones were isolated separately. The primary outcomes were the prevalence of microbial contamination on each surface of smartphones and associated bacterial species. Fisher's exact test was used to compare dichotomous outcomes. RESULTS: Eighty-four HCWs participated in this study. The touchscreen and posterior surface were contaminated in 27 (32.1%) and 39 (46.4%) smartphones, respectively, indicating that the posterior surface was more frequently contaminated (p = 0.041). Bacillus species and coagulase-negative staphylococci were isolated from each surface of the smartphones. CONCLUSIONS: The posterior surface of a smartphone was more significantly contaminated with bacteria than the touchscreen, regardless of having a cover. Therefore, routine cleaning of the posterior surface of a smartphone is recommended.

Isolation and characterization of endophytic bacteria for controlling root rot disease of Chinese jujube.

AIM: Fusarium oxysporum is the primary pathogen causing root rot disease that severely affects cultivation of jujube fruit in the Xinjiang province of China. The aim of this study was to identify endophytic bacteria in healthy jujube organs that could effectively suppress F. oxysporum growth. METHODS AND RESULTS: Different plant organs (leaves, twigs and roots) were collected from healthy Chinese jujube cultivated in southern Xinjiang province of China. The endophytic bacterium Brevibacterium halotolerans JZ7 was selected for its strong antagonistic activity and growth-promoting characteristics. Gas-chromatography mass-spectrometry analysis showed that acetoin, 2,3-butanediol and fenretinide were the three dominant volatile organic compounds produced by strain JZ7. Fenretinide strongly suppressed spore germination of F. oxysporum in vitro. Pot experiments showed that strain JZ7 colonized both the roots and rhizosphere soil of Chinese jujube and significantly reduced F. oxysporum level in jujube rhizosphere soil. CONCLUSION: We demonstrated that B. halotolerans JZ7 can be developed into a biological control agent to combat root rot disease of Chinese jujube in the Xinjiang province of China. SIGNIFICANCE AND IMPACT OF THE STUDY: The suggested strategy for biological control of jujube root rot disease is fully in accordance with the current principles of sustainability.

Anti-staphylococcal activity of a cyclic lipopeptide, C15 -bacillomycin D, produced by Bacillus velezensis NST6.

AIM: The aim of this study was to assess antibacterial activity of a novel Bacillus velezensis strain NST6, and further identify its active compound against pathogenic Staphylococcus strains for clinical therapeutic applications. METHODS AND RESULTS: In this study, a novel B. velezensis strain NST6 harbouring strong antimicrobial activity against human pathogenic bacteria was isolated from a soil sample. The solvent extract of the strain exhibited strong antibacterial activity against Gram-positive and Gram-negative bacteria in disc diffusion assay and measurement of minimal inhibitory concentration and bactericidal concentration, of which it showed notable efficacy to Staphylococcus species including Staphylococcus epidermidis, Staphylococcus aureus and methicillin-resistant S. aureus. Strong antibacterial effect against pathogenic S. aureus and low toxicity of the bacterial extract were further validated in Caenorhabditis elegans model. Moreover, by antibacterial activity-guided fractionation using RP-HPLC and LC-MS, we defined C15 -bacillomycin D as the anti-staphylococcal compound produced by the strain. CONCLUSION: The primary anti-staphylococcal compound from B. velezensis NST6 was identified as a cyclic lipopeptide, C15 -bacillomycin D, which proved its potential to treat Staphylococcus strains in vitro and in vivo experiments with insignificant level of toxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: We provide an alternative treatment option to Staphylococcus infections by investigating the specific anti-staphylococcal activity of C15 -bacillomycin D produced by a B. velezensis strain.