Epidemiology and zoonotic potential of Livestock-associated Staphylococcus aureus isolated at Tamil Nadu, India.

BACKGROUND: Staphylococcus aureus is part of normal flora and also an opportunistic pathogen responsible for a wide range of infections in both humans and animals. Livestock-associated S. aureus (LA-SA) has gained importance in recent years due to its increased prevalence in recent years, becoming a worry in public health view. This study aimed to study the epidemiology of LA-SA strains in Madurai district, Tamil Nadu, India. METHODS: A total of 255 samples were collected from bovine and other small ruminants like goats and sheep nares (n = 129 and n = 126 respectively). Nasal swab samples were collected from study animals with sterile sample collecting cotton swabs (Hi-Media, Mumbai). Samples were transported to the lab in Cary-Blair Transport media for further analysis. The samples were tested for S. aureus using antibiotic selection and PCR-based assays. The pathogenicity of the bacteria was assessed using chicken embryo models and liver cross-sections were used for histopathology studies. RESULTS: The prevalence rate in bovine-associated samples was 42.63% but relatively low in the case of small ruminants associated samples with 28.57% only. The overall prevalence of S. aureus is found to 35.6% and MRSA 10.98% among the study samples. The antibiogram results that LA-SA isolates were susceptible to aminoglycosides and tetracyclines but resistant to ß-lactam drugs. The biofilm formation results showed that the LA-SA isolates are weak to high-capacity biofilm formers. The enterotoxigenic patterns revealed that most of the isolated strains are enterotoxigenic and possess classical enterotoxins. The survival analysis of chicken embryos suggested that the Bovine-associated strains were moderately pathogenic. CONCLUSION: The study concluded that economically important livestock animals can act as reservoirs for multi-drug resistant and pathogenic which in-turn is a concern for public health as well as livestock health.

Development and Characterization of Bio-Based Composite Films for Food Packing Applications Using Boiled Rice Water and Pistacia vera Shells.

Customer demand for natural packaging materials in the food industry has increased. Biocomposite films developed using boiled rice water could be an eco-friendly and cost-effective packaging product in the future. This study reports the development of bio-based films using waste materials, such as boiled rice water (matrix) and Pistacia vera shells (reinforcement material), using an adapted solution casting method. Several film combinations were developed using various concentrations of plasticizing agent (sorbitol), thickening agent (oil and agar), and stabilizing agents (Arabic gum, corn starch, and Pistacia vera shell powder). Various packaging properties of the film were analyzed and examined to select the best bio-based film for food packaging applications. The film fabricated with Pistacia vera shell powder in the biocomposite film exhibited a reduced water solubility, swelling index, and moisture content, as compared to polyethene packaging material, whereas the biocomposite film exhibited poor antimicrobial properties, high vapor transmission rate, and high biodegradability rate. The packaging properties and characterization of the film indicated that the boiled rice water film with Pistacia vera shell powder was suitable for packaging material applications.

Investigation of interspecies crosstalk between probiotic Bacillus subtilis BR4 and Pseudomonas aeruginosa using metabolomics analysis.

Pseudomonas aeruginosa (PA) is an opportunistic pathogen that causes high mortality in cystic fibrosis patients. Treatment failures often occur due to the emergence of antibiotic resistance. Inhibition of virulence factors production without suppressing the growth of the pathogens is a potential alternative strategy to control the antibiotic resistance. In order to accomplish, three different interaction studies were performed using Bacillus subtilis BR4, PA and their extracellular contents. Firstly, co-cultivation was performed with different cell density of BR4 or PA. In co-culture setup (F), high cell density of BR4 significantly inhibits the biofilm formation of PA in a growth-independent manner (p < 0.01). To substantiate the biofilm inhibition, LC-MS/MS was performed and metabolic profile of monocultures and cocultures were compared. Multivariate analysis corroborated that metabolic profile of coculture setup (F) is drastically different from other coculture and monoculture setups. To check the effect of extracellular content of PA on BR4, supernatant of PA was extracted with ethyl acetate and different concentration of that extract (PA-EXT) was supplemented with BR4 culture. Exogenous supplementation PA-EXT (40 µg/mL) led to increased biofilm inhibitory activity (p < 0.01) in BR4. Further, to check the effect of extracellular content of BR4, PA was grown in the supernatant of BR4. PA survives in the spent media of BR4 without biofilm formation. Though 50% spent media of BR4 was replaced with fresh media, PA could not produce biofilm. In support of this, LC-MS/MS analysis has revealed that abundance of quorum sensing (QS) signals was reduced in the spent media grown PA than control. Furthermore, BR4 protects zebrafish larvae (Danio rerio) against PA infection and increases their survival rate (p < 0.05). We found that PA-induced oxidative stress and apoptosis were also significantly reduced in the BR4-pretreated larval group than control group. These results clearly indicate that BR4 exerts growth-independent QS inhibition in PA, suggesting that it could be used as a probiotic for future therapeutic interventions.

Bacillus subtilis BR4 derived stigmatellin Y interferes Pqs-PqsR mediated quorum sensing system of Pseudomonas aeruginosa.

Cell-to-cell communication is essentially required in bacteria for the production of multiple virulence factors and successful colonization in the host. Targeting the virulence factors production without hampering the growth of the pathogens is a potential strategy to control pathogenesis. To accomplish this, a total of 43 mangrove isolates were screened for quorum quenching (QQ) activity against Pseudomonas aeruginosa (PA), in which eight bacteria have shown antibiofilm activity without hampering the growth of the PA. Prominent QQ activity was observed in Bacillus subtilis BR4. Previously, we found that BR4 produces stigmatellin Y, a structural analogue of PQS signal of PA, which could competitively bind with PqsR receptor and inhibits the quorum sensing (QS) system of PA. Further, stigmatellin Y containing ethyl acetate extract (S-EAE) (100 µg ml-1 ) of BR4 significantly inhibits (p < 0.001) the biofilm formation of PA. Confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) analysis also fortified the QQ activity of BR4. Furthermore, S-EAE of BR4 (500 µg ml-1 ) has significantly reduced the production of virulence factors, including protease, elastase, pyocyanin and extracellular polysaccharides substances. Furthermore, liquid chromatography-mass spectrometry (LC-MS)/MS analysis affirms that BR4 intercepts the PQS-mediated QS system by reducing the synthesis of as many PQS signals, including precursor molecule (243.162313 Da) of PQS signal. Thus, S-EAE of B. subtilis BR4 could be used as a promising therapeutic agent to combat QS system-mediated pathogenesis of PA. Further therapeutic potentials of stigmatellin Y to be evaluated in clinical studies for the treatment of multidrug resistant PA.

Dietary Administration of Probiotic Aeromonas veronii V03 on the Modulation of Innate Immunity, Expression of Immune-Related Genes and Disease Resistance Against Aeromonas hydrophila Infection in Common Carp (Cyprinus carpio).

This study investigates the effects of dietary Aeromonas veronii V03 supplementation on growth performances, innate immunity, and expression of immune-related genes in lymphoid organs of Cyprinus carpio and resistance to Aeromonas hydrophila infection. Fish were fed for 4 weeks with basal diet (BD; without probiotic), and experiment diet containing different doses of A. veronii V03 at 3.2 × 107 (DI) and 3.5 × 109 (DII) CFU g-1 of diet. At the end of the probiotic feeding trial, fish were challenged with A. hydrophila, and the percentage of survival rates was recorded over 7 days. Results revealed that fish fed with A. veronii V03 demonstrated a significant improvement in growth and enhancement of innate immunity, including respiratory burst, myeloperoxidase, and lysozyme activities, and total immunoglobulin level compared with BD fed to fish. Relatively, expression of cytokines (MyD88, IL-1ß1, IL-8, and IL-10) and c- and g-type lysozymes were significantly up- and downregulated in lymphoid organs of fish. Moreover, dietary supplementation of A. veronii V03 exhibited significantly (p < 0.001) higher survival rates of DI (90%) and DII (96.66%) compared with BD (53.33%) fed fish against A. hydrophila infection. These findings help to understand the effects of probiotic A. veronii V03 administrated feed influences on growth and ailment resistance to A. hydrophila infection by regulating innate and systemic immunity in common carp fish.

Desert Environments Facilitate Unique Evolution of Biosynthetic Potential in Streptomyces.

Searching for new bioactive metabolites from the bacterial genus Streptomyces is a challenging task. Combined genomic tools and metabolomic screening of Streptomyces spp. native to extreme environments could be a promising strategy to discover novel compounds. While Streptomyces of desertic origin have been proposed as a source of new metabolites, their genome mining, phylogenetic analysis, and metabolite profiles to date are scarcely documented. Here, we hypothesized that Streptomyces species of desert environments have evolved with unique biosynthetic potential. To test this, along with an extensive characterization of biosynthetic potential of a desert isolate Streptomyces sp. SAJ15, we profiled phylogenetic relationships among the closest and previously reported Streptomyces of desert origin. Results revealed that Streptomyces strains of desert origin are closer to each other and relatively distinct from Streptomyces of other environments. The draft genome of strain SAJ15 was 8.2 Mb in size, which had 6972 predicted genes including 3097 genes encoding hypothetical proteins. Successive genome mining and phylogenetic analysis revealed the presence of putative novel biosynthetic gene clusters (BGCs) with low incidence in another Streptomyces. In addition, high-resolution metabolite profiling indicated the production of arylpolyene, terpenoid, and macrolide compounds in an optimized medium by strain SAJ15. The relative abundance of different BGCs in arid Streptomyces differed from the non-arid counterparts. Collectively, the results suggested a distinct evolution of desert Streptomyces with a unique biosynthetic potential.

Production and characterization of exopolysaccharide from the sponge-associated Bacillus subtilis MKU SERB2 and its in-vitro biological properties.

In this study, the sponge-associated a potential endosymbiotic bacterium, Bacillus subtilis MKU SERB2 was identified and optimized the production of exopolysaccharide (EPS) by using response surface methodology (RSM). The central composite rotatable design (CCRD) exhibited the highest yield of EPS (617.81 µg/mL) obtained from the optimized medium containing 11.5 g/L of sucrose, 3.5 g/L of yeast extract, 3.0 g/L of peptone, and 2.5 g/L of calcium chloride. Fourier transform infrared (FTIR) spectrum of purified EPS indicated that the presence of carboxyl, hydroxyl, and amide as functional groups, and their structural composition was confirmed by 1H and 13C nuclear magnetic resonance (NMR) analysis. Moreover, the fibrous, porous and semi-crystalline nature of EPS was confirmed by SEM and X-ray powder diffraction (XRD) analysis and the EDX inferred demonstrated the presence of C, Na, O, N, S, and Cl respectively. Further, the isolated EPS exhibited potent antioxidant activity and moderate anticoagulant efficacy whereas there was no hemolytic and lymphocytes toxicity. Overall, our result suggests that the functional and biological properties of the EPS imply the potential applications in food and pharmaceutical industries in the future.

Inhibition of biofilm formation and quorum sensing mediated virulence in Pseudomonas aeruginosa by marine sponge symbiont Brevibacterium casei strain Alu 1.

The alternative antimicrobial strategies that mitigate the threat of antibiotic resistance is the quorum-sensing inhibition (QSI) mechanism, which targets autoinducer dependent virulence gene expression in bacterial pathogens. N-acyl homoserine lactone (AHL) acts as a key regulator in the production of virulence factors and biofilm formation in Pseudomonas aeruginosa PAO1 and violacein pigment production in Chromobacterium violaceum ATCC 12472. In the present study, the marine sponge Haliclona fibulata symbiont Brevibacterium casei strain Alu 1 showed potential QSI activity in a concentration-dependent manner (0.5-2% v/v) against the N-acyl homoserine lactone (AHL)-mediated violacein production in C. violaceum (75-95%), and biofilm formation (53-96%), protease (27-82%), pyocyanin (82-95%) and pyoverdin (29-38%) productions in P. aeruginosa. Further, the microscopic analyses validated the antibiofilm activity of the cell-free culture supernatant (CFCS) of B. casei against P. aeruginosa. Subsequently, the biofilm and pyoverdin inhibitory efficacy of the ethyl acetate extract of B. casei CFCS was assessed against P. aeruginosa. Further, the gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of variety of components in which diethyl phthalate was found to be a major active component. This phthalate ester, known as diethyl ester of phthalic acid, could act as a potential therapeutic agent for preventing bacterial biofilm and virulence associated infectious diseases.

Genomic islands and the evolution of livestock-associated Staphylococcus aureus genomes.

BACKGROUND: Genomic Islands (GIs) are commonly believed to be relics of horizontal transfer and associated with specific metabolic capacities, including virulence of the strain. Horizontal gene transfer (HGT) plays a vital role in the acquisition of GIs and the evolution and adaptation of bacterial genomes. OBJECTIVE: The present study was designed to predict the GIs and role of HGT in evolution of livestock-associated Staphylococcus aureus (LA-SA). METHODS: GIs were predicted with two methods namely, Ensemble algorithm for Genomic Island Detection (EGID) tool, and Seq word Sniffer script. Functional characterization of GI elements was performed with clustering of orthologs. The putative donor predictions of GIs was done with the aid of the pre_GI database. RESULTS: The present study predicted a pan of 46 GIs across the LA-SA genomes. Functional characterization of GI sequences revealed few unique results like the presence of metabolic operons like leuABCD and folPK genes in GIs and showed the importance of GIs in the adaptation to the host niche. The developed framework for GI donor prediction results revealed Rickettsia and Mycoplasma as the major donors of GI elements. CONCLUSIONS: The role of GIs during the evolutionary race of LA-SA could be concluded from the present study. Niche adaptation of LA-SA enhanced presumably due to these GIs. Future studies could focus on the evolutionary relationships between Rickettsia and Mycoplasma sp. with S. aureus and also the evolution of Leucine/Isoleucine mosaic operon (leuABCD).

Induction of mitochondria-mediated apoptosis and suppression of tumor growth in zebrafish xenograft model by cyclic dipeptides identified from Exiguobacterium acetylicum.

Colorectal cancer is the most common type of gastrointestinal cancers with poor survival and limited therapeutic options. In this study, four structurally different cyclic dipeptides (or diketopiperazine) were isolated and identified as cyclo (L-Pro-L-Leu), cyclo (L-Pro-L-Val), cyclo (L-Pro-L-Phe) and cyclo (L-Pro-L-Tyr) from the ethyl acetate extract in the cell-free filtrate of Exiguobacterium acetylicum S01. The anticancer potential of identified DKPs on colorectal cancer HT-29 cells in vitro and in vivo zebrafish xenograft model was evaluated. The MTT (3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide)) assay showed that four DKPs exhibited significant inhibition of HT-29 cells viability in a dose-dependent manner whereas there were no cytotoxic effects on normal mouse fibroblast 3T3 cells. Also, we observed that all DKPs induce early and late apoptotic cell death in HT-29 cells. Moreover, the expression levels of apoptotic (cytochrome-c, caspase-3 and Bid) and anti-apoptotic (Bcl-2) markers were up- and down-regulated in HT-29 cells in response to DKPs treatments. Furthermore, these four DKPs remarkably inhibited the tumor progression in a zebrafish xenograft model within a nonlethal dose range. Overall, our findings suggest that cyclic dipeptides derived from E. acetylicum S01 could be promising chemopreventive/ therapeutic candidates against cancer.

In vitro and in vivo efficacy of methyl oleate and palmitic acid against ESBL producing MDR Escherichia coli and Klebsiella pneumoniae.

PURPOSE: Antibiotic resistance is a huge problem that stays to challenge the healthcare sector in a large part of the world in both developing and developed countries. The spread of multi drug resistant (MDR) bacteria in hospital and community settings remains a widely uncertain problem and a heavy burden to health services. METHODS: This study unveils the in vitro and in vivo anti-ESBL potential of Methyl oleate (MO) and Palmitic acid (PA) against ESBL producing MDR bacterial pathogens such as Escherichia coli and Klebsiella pneumoniae. Microscopic observations unveiled the anti-ESBL efficacy of test compounds. MTT assay, in vivo anti-infective efficiency of MO and PA was tested with different concentrations. RESULTS: The pure compounds of MO and PA from Oxynema thaianum demonstrated high inhibitory activity in MIC and MBC assays against MDR E. coli and K. pneumoniae. Moreover, the anti-ESBL potential of MO and PA was validated through light, confocal laser scanning and scanning electron microscopic analyses. The IC50 values of MO and PA against A549 cells was recorded as 625 µg mL-1 and 514 µg mL-1, respectively. In Artemia nauplii cytotoxicity assay, the LC50 value of MO and PA were recorded as 53.33 µg mL-1 and 50 µg mL-1 respectively. The 96 h lethal concentrations obtained for Lobeo rohita treated with different concentrations of Methyl oleate and Palmitic acid. The LC50 for MO and PA was 50 mg L-1 and 100 mg L-1, respectively. CONCLUSION: Therefore the study concluded that the promising effects of MO and PA can be used as an alternative biological agent which could be positively explored to treat ESBL producing MDR pathogens.

Diapolycopenedioic-acid-diglucosyl ester and keto-myxocoxanthin glucoside ester: Novel carotenoids derived from Exiguobacterium acetylicum S01 and evaluation of their anticancer and anti-inflammatory activities.

Inflammation is pivotal for the development of gastrointestinal cancer and linked to poor survival and limited therapeutic options. In this study, six structurally different carotenoids were isolated and identified from the methanolic extract of Exiguobacterium acetylicum S01 namely lycopene (Car-I), diapolycopenedioic-acid-diglucosyl-ester (Car-II), ß-carotene (Car-III), zeaxanthin (Car-IV), astaxanthin (Car-V), and keto-myxocoxanthin glucoside-ester (Car-VI). Further, their anti-cancer, anti-inflammatory, and antioxidant potentials were evaluated. The MTT assay was used to determine the effect of carotenoids on viability of colorectal cancer (HT-29) as well as peripheral blood mononuclear cells (PBMCs). Results revealed that all the six carotenoids were demonstrated a significant inhibition of HT-29 cells viability in a dose-dependent manner whereas there was no cytotoxic effect in PBMCs. The study also recorded that six carotenoids considerably inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) production, tumor necrosis factor-alpha (TNF-α), and lipid peroxidation in PBMCs. Moreover, antioxidant potentials of Car-II and Car-VI were significantly (p = 0.001) higher than ascorbic acid as determined by a 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Therefore, our results ascertained the role of carotenoids derived from E. acetylicum S01 in developing potential therapeutic agents for inflammation-associated cancer.

Optimization of submerged fermentation process for improved production of ß-carotene by Exiguobacterium acetylicum S01.

Carotenoids are natural pigments with substantial applications in nutraceutical, pharmaceutical, and food industries. In this study, optimization of the fermentation process for enhancement of ß-carotene and biomass production by Exiguobacterium acetylicum S01 was achieved by employing statistical designs including the Placket-Burman design (PBD) and response surface methodology (RSM). Among the seven variables investigated by two levels in PBD, glucose, peptone, pH and temperature were indicated as crucial variables (p < 0.0001) for ß-carotene and biomass productivity. Response surface methodology was further applied to evaluate the optimal concentrations of these four variables for maximum ß-carotene and biomass productivity. The optimized medium contained glucose 1.4 g/L, peptone 26.5 g/L, pH 8.5, and temperature 30 °C, respectively. A significant increase in ß-carotene (40.32 ± 2.55 mg/L) and biomass (2.19 ± 0.10 g/L) productivities in E. acetylicum S01 were achieved by using RSM, which was 3.47-fold and 2.36-fold higher in the optimized medium compared to the un-optimized medium. Further, the optimum fermentation condition in the 5-L bioreactor was achieved a maximal ß-carotene yield of 107.22 ± 5.78 mg/L within 96 h. Moreover, the expression levels of carotenoid biosynthetic genes (phytoene desaturase (CrtI) and phytoene synthase (CrtB)) were up-regulated (2.89-fold and 3.71-fold) in E. acetylicum under the optimized medium conditions. Overall, these results suggest that E. acetylicum S01 can be used as a promising microorganism for the commercial production of ß-carotene.

Analyses of Livestock-Associated Staphylococcus aureus Pan-Genomes Suggest Virulence Is Not Primary Interest in Evolution of Its Genome.

Staphylococcus aureus is not only part of normal flora but also an opportunistic pathogen relevant to microbial genomics, public health, and veterinary medicine. In addition to being a well-known human pathogen, S. aureus causes various infections in economically important livestock animals such as cows, sheep, goats, and pigs. There are very few studies that have examined the pan-genome of S. aureus or the host-specific strains' pan-genomes. We report on livestock-associated S. aureus' (LA-SA) pan-genome and suggest that virulence is not the primary interest in evolution of its genome. LA-SA' complete genomes were retrieved from the NCBI and pan-genome was constructed by high-speed Roary pipeline. The pan-genome size was 4637 clusters, whereas 42.46% of the pan-genome was associated with the core genome. We found 1268 genes were associated with the strain-unique genome, and the remaining 1432 cluster with the accessory genome. COG (clusters of orthologous group of proteins) analysis of the core genes revealed 34% of clusters related to metabolism responsible for amino acid and inorganic ion transport (COG categories E and P), followed by carbohydrate metabolism (category G). Virulent gene analysis revealed the core genes responsible for antiphagocytosis and iron uptake. The fluidity of pan-genome was calculated as 0.082 ± 0.025. Importantly, the positive selection analysis suggested a slower rate of evolution among the LA-SA genomes. We call for comparative microbial and pan-genome research between human and LA-SA that can help further understand the evolution of virulence and thus inform future microbial diagnostics and drug discovery.

Functional Characterization of Probiotic Potential of Novel Pigmented Bacterial Strains for Aquaculture Applications.

The bioprospecting proficient of novel pigmented probiotic strains with respect to aquaculture industry was unexplored hitherto. In this study, we investigated the probiotic potential of novel pigmented bacterial strains isolated from the indigenous soil sediments in their vicinal habitats, which were screened for their antimicrobial activity against aquatic pathogens using agar well diffusion assay. The strains namely Exiguobacterium acetylicum (S01), Aeromonas veronii (V03), and Chryseobacterium joostei (V04) were phenotypically identified and confirmed by 16S rRNA gene sequence analysis. Further characterization revealed that strains S01 and V03 survive relatively in lower pH and higher bile salt concentrations and possess good adherence ability and broad-spectrum antibiotic susceptibility. The isolate S01 exhibited the higher adhesion ability to hydrocarbons (82%) and mannose-specific adhesion (msa) gene expression. Additionally, the probiotic effects were evaluated in Artemia nauplii fed with algae supplemented with S01, V03, and V04 strains (2.7 × 107 cfu/mL) for 3 days under axenic environment. We observed a significant increase (p < 0.05) in the survival rate of Artemia nauplii treated with S01 (83 ± 5%) and V03 (55 ± 5%), whereas the survival rate was only 30 ± 0% in the untreated group. Moreover, the individual length (IL) was increased in treated group S01 (156.7 ± 2.2 µm), V03 (146.1 ± 3.4 µm), and V04 (134.4 ± 2.5 µm) compared with untreated group (116.0 ± 4.8 µm). Our results revealed that E. acetylicum S01 exhibits desirable functional probiotic attributes compared to A. veronii and C. joostei and it would be a promising probiotic strain, which can be efficiently used in the aquaculture applications.

Modulation of innate immunity, expression of cytokine genes and disease resistance against Aeromonas hydrophila infection in goldfish (Carassius auratus) by dietary supplementation with Exiguobacterium acetylicum S01.

Probiotic strains play an increasing role in the production of healthy animals used as a food source. Elucidating the mechanisms of action that allow probiotic-driven immunomodulation may facilitate different applications such as the prevention of infectious diseases in food organisms. This study elucidates the probiotic effects of Exiguobacterium acetylicum S01 on the growth, haematological profile, innate immune capacity, expression of cytokine genes, and resistance to diseases of Carassius auratus caused by Aeromonas hydrophila infection. Three fish groups were fed with the following diets containing different doses of E. acetylicum S01 (CFU g-1): basal diet 0 (BD, without probiotic), 2.5 × 107 (DI) and 2.7 × 109 (DII)-CFU g-1 for 4 weeks. After 4 weeks, the fish were injected intraperitoneally with A. hydrophila and the percentage of survival was recorded over 21 days of post-challenge. Results revealed that dietary supplementation of E. acetylicum S01 significantly (P < 0.05) enhanced the growth, haematological profile and cellular immune responses including respiratory burst, phagocytic activities and antimicrobial enzymes (myeloperoxidase and lysozyme) and total immunoglobulin levels were improved by probiotic feeding at both occasions. Comparatively, expression of c- and g-type lysozyme followed by pro- and anti-inflammatory cytokines (IL-1ß, IL-10 and TGFß) was up-regulated in kidney, head-kidney and spleen. Moreover, fish fed with diet DII had a significantly higher (P < 0.05) survival rate (73.2%) after challenging. The survival rate was only 33.2% of the BD group against A. hydrophila infection. Our results revealed that E. acetylicum S01 delivered probiotic in feed exerts its influence on growth performance and provides disease resistance by stimulating the immune system at the cellular and molecular levels in C. auratus.

Spatial Physiochemical and Metagenomic Analysis of Desert Environment.

Investigating the bacterial diversity and their metabolic capabilities are crucial for interpreting ecological patterns in desert environment, and assessing the presence of exploitable microbial resources. In this study, we evaluated the spatial heterogeneity of physico-chemical parameters, soil bacterial diversity and metabolic adaptation at meter scale. Soil samples were collected from two quadrates a desert environment (Thar Desert, India) which face hot arid climate with very little rainfall and extreme temperatures. Analysis of physico-chemical parameters and subsequent variance analysis (p-values < 0.05) revealed that sulfate, potassium and magnesium ions were the most variable between the quadrates. Microbial diversity of the two quadrates was studied using Illumina bar coded sequencing by targeting V3-V4 regions of 16S rDNA. As the results, 702504 high-quality sequence reads, assigned to 173 operationaltaxonomic units (OTUs) at species level. The most abundant phyla in both quadrates were Actinobacteria (38.72%), Proteobacteria (32.94%), and Acidobacteria (9.24%). At genus level, Gaiellarepresented highest prevalence, followed by Streptomyces, Solirubrobacter, Aciditerrimonas, Geminicoccus, Geodermatophilus, Microvirga, and Rubrobacter. Between the quadrates, significant difference (p-values < 0.05) was found in the abundance of Aciditerrimonas, Geodermatophilus Geminicoccus, Ilumatobacter, Marmoricola, Nakamurella and Solirubrobacter. Metabolic functional mapping revealed diverse biological activities, and was significantly correlated with physico-chemical parameters. The results revealed spatial variation of ions, microbial abundance and functional attributes in the studied quadrates, and patchy nature in local scale. Interestingly, abundance ofthe biotechnologically important phylum Actinobacteria, with large proposition of unclassified speciesin the desert suggested that this arid environment is the promising site for bioprospection.

Biosynthetic Potential of Bioactive Streptomycetes Isolated From Arid Region of the Thar Desert, Rajasthan (India).

Acquisition of Actinobacteria, especially Streptomyces from previously underexplored habitats and the exploration of their biosynthetic potential have gained much attention in the rejuvenated antibiotics search programs. Herein, we isolated some Streptomyces strains, from an arid region of the Great Indian Thar Desert, which possess an ability to produce novel bioactive compounds. Twenty-one morphologically distinctive strains differing in their aerial and substrate mycelium were isolated by employing a stamping method. Among them, 12 strains were identified by a two-level antimicrobial screening method, exerting antimicrobial effects against a panel of indicator strains including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus species. Based on their potent antimicrobial activity, four isolates were further explored by 16S rRNA gene-based identification, genetic screening, and metabolomic analysis; and it was found that these strains belong to the genus Streptomyces. The selected strains were found to have polyketide synthase and non-ribosomal peptide synthetase systems. In addition, extracellular metabolomic screening revealed that the isolates produced analogs of doxorubicinol, pyrromycin, erythromycin, and 6-13 other putative novel metabolites. These results demonstrate the significance of Streptomyces inhabiting the arid region of Thar Desert, suggesting that similar arid environments can be considered as the reservoirs of novel Streptomyces strains that could have biotechnological significance.

A novel antimicrobial therapy for the control of Aeromonas hydrophila infection in aquaculture using marine polysaccharide coated gold nanoparticle.

In the present study, we prepared fucoidan coated Au-NPs (Fu-AuNPs), and examined its antimicrobial activity against Aeromonas hydrophila. The green synthesized Fu-AuNPs were bio-physically characterized by Ultraviolet-visible (UV-Vis) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Higher Transmission Electron Microscopy (HR-TEM), Zeta potential analysis and Energy Dispersive X-ray spectroscopy (EDX). Fu-AuNPs were crystalline in nature, spherical to triangular in shape, with particle size ranging within 10-100 nm. The synthesized Fu-AuNPs at 100 µg mL-1 showed inhibition zone against A. hydrophila (23.2 mm) which is much higher than that of commercial antibiotic chloramphenicol (17.3 mm). The biofilm inhibitory activity of Fu-AuNPs against Gram negative (Aeromonas hydrophila) was higher. Light and confocal laser scanning microscopic observations showed that the Fu-AuNPs at 100 µg mL-1 inhibited the biofilm of A. hydrophila. The cytotoxicity study indicated that Fu-AuNPs were effective in inhibiting the viability of human cervical cancer cells (HeLa) at 100 µg mL-1. In another experiment, the antibacterial effect of Fu-AuNPs on tilapia, Oreochromis mossambicus were evaluated in vivo. The mortality rate of O. mossambicus infected by A. hydrophila was much higher (90%), whereas, the mortality of O. mossambicus that received Fu-AuNPs followed by challenge with A. hydrophia was reduced to 30%. This study concludes that Fu-AUNPs are effective in the control of A. hydrophila infections in O. mossambicus.

Extended spectrum ß-lactamase producing Escherichia coli and Klebsiella pneumoniae: critical tools for antibiotic resistance pattern.

Drug resistance is a phenomenon where by an organism becomes fully or partially resistant to drugs or antibiotics being used against it. Antibiotic resistance poses an exacting intimidation for people with underlying medical immune conditions or weakened immune systems. Infections caused by the enzyme extended spectrum ß-lactamase (ESBL) producing multi drug resistance (MDR) Enterobacteriaceae especially Escherichia coli and Klebsiella pneumoniae are resistant to a broad range of beta lactams, including third generation cephalosporins. Among all the pathogens, these two MDR E. coli and K. pneumoniae have emerged as one of the world's greatest health threats in past two decades. The nosocomial infections caused by these ESBL producing MDR E. coli and K. pneumoniae complicated the therapy and limit treatment options.