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Microbial resistance and deprivation of the effective drugs have become the foremost problem that propels to seek out for advanced approach. This concept initiated a need to search for more effective antimicrobial compounds from reliable sources. The Streptomyces is grouped under phylum Actinobacteria and are considered prolific producers of antibiotics, around 70% of presently available antibiotics are contributed by Streptomyces alone. In this study, Mangroves of the Mangalore Coast offered a unique source for screening Actinomyces group of microorganisms. We investigated on the four soil samples collected from Mangrove swamps of Mangalore, Karnataka, India. Based on their culture traits, the 18 distinct Actinomyces isolates were analyzed through a series of morphological and biochemical tests on starch casein nitrate (SCN) media. Culture biomasses were subjected for intracellular protein extraction through acetone precipitation method; the extracted proteins from each Actinomyces isolate were examined for antimicrobial activity against test organisms. The isolate ANTB‐YKMU4 showed potential antimicrobial activity against significant number of test organisms; Bacillus cereus, Proteus vulgaris, Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas aeruginosa. The isolate ANTB‐YKMU4 through 16 s rRNA gene sequence analysis was identified as Streptomyces tauricus strain with GenBank accession no. MW785875.1. The S. tauricus further cultivated for efficient biomass growth on SCN media for subsequent protein extraction and purification by a series of Electrophoretic and chromatographic techniques. Thus, by intracellular extractions from S. tauricus resulted in the identification of peptide with a molecular weight of 266 Da that was characterized by LC‐MS. [ABSTRACT FROM AUTHOR]

Pukzing cave, the largest cave of Mizoram, India was explored for bacterial diversity. Culture dependent method revealed 235 bacterial isolates using three different treatments. Identity of the microbial species was confirmed by 16S rDNA sequencing. The highest bacterial population was recovered from heat treatment (n = 97;41.2%) followed by normal (n = 79;33.6%) and cold treatment (n = 59;25.1%) indicating dominance of moderate thermophiles. Antimicrobial potential of isolates showed 20.4% isolates having antimicrobial ability against tested pathogens. Amplicon sequencing of PKSI, PKSII and NRP specific genes revealed presence of AMP genes in the microbial population. Six microbial pathogens were selected for screening as they are well known for different disease cause organism in various fields such as agriculture and human health. Cave environment harbors unique microbial flora and hypervariable region V4 is more informative. Higher activity of AMP assay against these microbes indicates that cave microbial communities could be potential source of future genomic resources. • Study revealed Pukzing cave ecosystem as a unique source of endemic and moderate thermophilic microorganisms. • Amplicon sequencing of PKSI, PKSII and NRP specific genes revealed presence of AMP genes in the microbial population. • Cave environment harbours unique microbial flora and hypervariable region V4 was found to be more informative. • The study concludes that cave microbial communities could be potential source of future genomic resources. [ABSTRACT FROM AUTHOR]

Aspergillus flavus is a leading cause of corneal infections in India and worldwide, resulting in severe visual impairment. We studied the host immune response towards A. flavus in immortalised human corneal epithelial cells (HCEC) and found increased expression of Toll‐like receptors, antimicrobial peptides and proinflammatory cytokines like IL‐6 and IL‐8. Differential expressions of antimicrobial peptides were determined in corneal scrapings from A. flavus keratitis patients with significantly increased expression of LL‐37, S100A12 and RNase 7. Increased levels of IL‐22 expression were observed both in patients with A. flavus keratitis and in experimental mice model of corneal infections along with IL‐17, IL‐23 and IL‐18. IL‐22 is an important mediator of inflammation during microbial infections, and acts primarily on fibroblasts and epithelial cells. We observed constitutive expression of IL‐22 receptors in HCEC, and IL‐22 mediated activation of NF‐κB, MAPK pathways and STAT3, along with increased expression of antimicrobial peptides in these cells. IL‐22 also efficiently lessened cell deaths in corneal epithelial cells during A. flavus infection in vitro. Furthermore, recombinant IL‐22 reduced fungal burden and corneal opacity in an experimental murine model of A. flavus keratitis. [ABSTRACT FROM AUTHOR]

Background: The incidence of preterm birth (PTB) in India is around 13%. Specific bacterial communities or individual taxon living in the vaginal milieu of pregnant women is a potential risk factor for PTB and may play an important role in its pathophysiology. Besides, bacterial taxa associated with PTB vary across populations. Objective: Conduct a comparative analysis of vaginal microbiome composition and microbial genomic repertoires of women who enrolled in the Interdisciplinary Group for Advanced Research on Birth Outcomes – A DBT India Initiative (GARBH-Ini) pregnancy cohort to identify bacterial taxa associated with term birth (TB) and PTB in Indian women. Methods: Vaginal swabs were collected during all three trimesters from 38 pregnant Indian women who delivered spontaneous term (n=20) and preterm (n=18) neonates. Paired-end sequencing of V3-V4 region of 16S rRNA gene was performed using the metagenomic DNA isolated from vaginal swabs (n=115). Whole genome sequencing of bacterial species associated with birth outcomes was carried out by shotgun method. Lactobacillus species were grown anaerobically in the De Man, Rogosa and Sharpe (MRS) agar culture medium for isolation of genomic DNA and whole genome sequencing. Results: Vaginal microbiome of both term and preterm samples reveals similar alpha diversity indices. However, significantly higher abundance of Lactobacillus iners (p-value All_Trimesters<0.02), Megasphaera sp (p-value1st_Trimester <0.05), Gardnerella vaginalis (p-value2nd_Trimester= 0.01) and Sneathia sanguinegens (p-value2nd_Trimester <0.0001) were identified in preterm samples whereas higher abundance of L. gasseri (p-value3rd_Trimester =0.010) was observed in term samples by Wilcoxon rank-sum test. The relative abundance of L. iners , and Megasphaera sp. were found to be significantly different over time between term and preterm mothers. Analyses of the representative genomes of L. crispatus and L. gasseri indicate presence of secretory transcriptional regulator and several ribosomally synthesized antimicrobial peptides correlated with anti-inflammatory condition in the vagina. These findings indicate protective role of L. crispatus and L. gasseri in reducing the risk of PTB. Conclusion: Our findings indicate that the dominance of specific Lactobacillus species and few other facultative anaerobes are associated with birth outcomes. [ABSTRACT FROM AUTHOR]

Antheraea mylitta , a tropical non-mulberry silkworm, is cultivated for tasar silk production in India. Several defense molecules including few antimicrobial peptides (AMPs) and proteins have been identified from this insect. Here, we have isolated and purified an antimicrobial tri-peptide by sequential chromatographic separation procedures. The amino acid sequence of the peptide was determined as NH 2 -Gln-Ala-Lys-COOH (QAK) using MALDI MS/MS fragmentation analysis. Further, the peptide was synthesized in vitro following solid phase chemistry of peptide synthesis and acetylated by acetic anhydride reaction. Antimicrobial activities of non-acetylated and acetylated QAK were tested against both Escherichia coli and Staphylococcus aureus bacteria. Acetylated peptide inhibited bacterial growth more effectively and its minimum inhibitory concentration (MICs) was found lower than non-acetylated peptide. SEM studies revealed more membrane damage and release of intracellular materials like β-galactosidase enzyme from acetylated peptide treated bacteria in comparison to non-acetylated QAK. At MIC, acetylated peptide did not show any significant hemolytic activity against rabbit erythrocytes. The results suggest that acetylated-QAK is a promising new antimicrobial peptide and can be used for therapeutic purpose. Image 1 • Purification of an antimicrobial peptide from hemolymph of A. mylitta. • Sequence determination as Q-A-K and chemical synthesis of this peptide. • QAK was acetylated and acetylated form showed higher antibacterial activity. • No significant hemolytic activity was observed for the peptide. • Peptide disrupts bacterial membrane and releases intracellular materials. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is an opportunistic pathogen and is the major cause of corneal infections in India and worldwide. The increase in antimicrobial resistance among Pseudomonas has prompted rise in significant research to develop alternative therapeutics. Antimicrobial peptides (AMPs) are considered as potent alternatives to combat bacterial infections. In this study, we investigated the role of S100A12, a host defense peptide, against PAO1 and an ocular clinical isolate. Increased expression of S100A12 was observed in corneal tissues obtained from Pseudomonas keratitis patients by immunohistochemistry. S100A12 significantly inhibited growth of Pseudomonas in vitro as determined from colony forming units. Furthermore, recombinant S100A12 reduced the corneal opacity and the bacterial load in a mouse model of Pseudomonas keratitis. Transcriptome changes in PAO1 in response to S100A12 was investigated using RNA sequencing. The pathway analysis of transcriptome data revealed that S100A12 inhibits expression of genes involved in pyoverdine synthesis and biofilm formation. It also impedes several important pathways like redox, pyocyanin synthesis and type 6 secretion system (T6SS). The transcriptome data was further validated by checking the expression of several affected genes by quantitative PCR. Our study sheds light on how S100A12 impacts Pseudomonas and that it might have the potential to be used as therapeutic intervention in addition to antibiotics to combat infection in future. • Increased protein expression of S100A12 in patients with Pseudomonas keratitis. • S100A12 inhibits growth of P. aeruginosa in vitro. • Transcriptome data show reduced expression of genes for biofilm formation and pyoverdine synthesis in PAO1 by S100A12. • Topical application of S100A12 promotes protection during P. aeruginosa infection in a murine model of keratitis. [ABSTRACT FROM AUTHOR]

Anti-bacterial activity was evaluated in different crude extracts of five commercially important edible marine bivalves, namely Meretrix costa (Chemnitz), Polymesoda (Geloina) P erosa (Solander), Perna viridis (Linnaeus), Crassostrea gryphoides (Schlothim) and Villorita cyprinoides (Grey), collected from the coast of Goa (India). Three different procedures, viz, methanol (MeOH), PBS and acid-enzyme hydrolysis (AEH), were used to prepare the extracts. The efficacy of the extraction procedure was assessed on the antimicrobial activity. Antimicrobial assay was carried out against 8 bacterial strains (3 Gram positive and 5 Gram negative bacteria) and 1 species of fungi. The AEH extracts showed higher activity against the tested organisms as compared to MeOH and PBS extracts. The findings of the present study confirmed that the antimicrobial activity in bivalves appeared to be dependent on the extraction process. Considerable interspecies variation was also observed. [ABSTRACT FROM AUTHOR]

Colonization of cyanobacteria and associated algae on a heritage monument (Buddha statue) of Santiniketan, India was studied. The dominating biofilms component is a filamentous cyanobacterium, Scytonema millei , which thrives on the monument, even when the surface temperature exceeds 60 °C during summer. The basic adaptive strategy of S. millei was analysed upon exposure to different temperature range and desiccation based on the changes in growth, morphology, and biochemical analysis. Maximum increase of growth (16.2%), chlorophyll-a (42.2%), carotenoids (24.4%), cellular carbohydrate content (102.2%), extracellular carbohydrate content (643.6%), and SOD activity (134.8%) were observed under stress conditions. The organism was found as desiccation and thermo-adaptive species. S. millei was more tolerant to heat soon after exposure in the dry state than in the wet state. Significant increase in carbohydrate content (cellular and extracellular) and SOD activity upon exposure to stress suggests their main importance in the stress tolerance of S. millei. These findings suggest that the dominating cyanobacteria have developed different defense mechanisms enough to survive in extreme natural conditions of tropical regions as well as in lab conditions. • Spatial distribution of cyanobacteria and algae on a heritage monument was studied. • Cyanobacteria and green algae colonized on exposed and shady parts respectively. • Scytonema millei was found as a desiccation and thermo-adaptive cyanobacterium. • Survival strategy of Scytonema millei was investigated. • Carbohydrate and SOD activity seems crucial for stress tolerance. [ABSTRACT FROM AUTHOR]