Sathyanarayanan Jayashree

Bio: Sathyanarayanan Jayashree is an academic researcher from Madurai Kamaraj University. The author has contributed to research in topics: Lactobacillus fermentum & Wild type. The author has an hindex of 10, co-authored 14 publications receiving 183 citations.

Identification of a novel antifungal peptide with chitin-binding property from marine metagenome.

Abstract: A novel antifungal peptide with 36 amino acids was identified by functional screening of a marine metagenomic library. The peptide did not show similarity with any existing antimicrobial peptide sequences in the databank. The108 bp ORF designated as mmgp1 was cloned and expressed in Escherichia coli BL21 (DE3) using pET expression system. Mass spectrometry analysis of the purified recombinant peptide revealed a molecular mass of 5026.9 Da. The purified recombinant peptide inhibited the growth of Candida albicans and Aspergillus niger. The peptide was predicted to adopt α- helical conformation with an extended coil containing a ligand binding site for N-acetyl-D-glucosamine. The α- helicity of the peptide was demonstrated by circular dichroism spectroscopy in the presence of chitin or membrane mimicking solvent, trifluoroethanol. The chitin binding property of the peptide was also confirmed by fast performance liquid chromatography.

Anti-adhesion Property of the Potential Probiotic Strain Lactobacillus fermentum 8711 Against Methicillin-Resistant Staphylococcus aureus (MRSA)

Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant pathogen and one of the leading causes of nosocomial infection worldwide. Probiotic bacteria play a significant role in preventive or therapeutic interventions of gastrointestinal infections in human as well as animals. In this study, we have investigated the adhesion property of the probiotic strain Lactobacillus fermentum MTCC 8711 and its ability to prevent the adhesion of MRSA to human colon adenocarcinoma cells, Caco-2. We have shown that L. fermentum could efficiently adhere to the Caco-2 cells. Also, we have shown that L. fermentum significantly reduced MRSA adhesion to Caco-2 cells. Three types of experiments were performed to assess the anti-adhesion property of L. fermentum against MRSA. Inhibition (Caco-2 cells were pre-treated with L. fermentum, and subsequently MRSA was added), competition (both L. fermentum and MRSA were added to Caco-2 cells simultaneously), and displacement or exclusion (Caco-2 cells were pre-treated with MRSA, and subsequently L. fermentum was added). In all three experiments, adhesion of MRSA was significantly reduced. Interestingly, L. fermentum could efficiently displace the adhered MRSA, and hence this probiotic can be used for therapeutic applications also. In cytotoxicity assay, we found that L. fermentum per se was not cytotoxic, and also significantly reduced the MRSA-induced cytotoxicity. The protective effect occurred without affecting Caco-2 cell morphology and viability.

Identification and characterization of bile salt hydrolase genes from the genome of Lactobacillus fermentum MTCC 8711.

Abstract: Lactobacillus fermentum is a lactic acid bacterium of probiotic importance, which is found ubiquitously in fermented milk products. Bile salt hydrolase (BSH) has a significant role in affording probiotic properties to lactobacilli. In the present study, two bsh genes encoding BSH1 and BSH2 were identified from the draft genome sequence of L. fermentum MTCC 8711. Nucleotide comparison revealed no significant similarity between bsh1 and bsh2 genes, whereas the deduced amino acid sequences showed 26 % sequence similarity between both BSH1 and BSH2. Pfam analysis revealed the presence of cys-2 active site residues in the catalytic pocket of both BSH1 and BSH2 highly essential for catalysis. Phylogentic analysis of BSH1 and BSH2 revealed the possible independent origin of these proteins in Lactobacillus. We cloned these genes in pSLp111.3, a Lactobacillus expression vector with signal peptide A (slpA) and expressed in the native L. fermentum strain for overexpression and extracellular secretion. The bsh1 gene failed to express and to produce promising BSH activity. However, bsh2 gene was overexpressed and the recombinant strain showed improved BSH activity. Induction of the recombinant strain with an optimal 2 % xylose concentration secreted 0.5 U/ml of the BSH into extracellular medium. Furthermore, the recombinant strain was able to completely assimilate the 100-μg/ml cholesterol within 24 h, whereas the native strain took 72 h for the complete assimilation of cholesterol.

Identification of Periplasmic α-Amlyase from Cow Dung Metagenome by Product Induced Gene Expression Profiling (Pigex)

Abstract: A metagenomic library was constructed by cloning cow dung metagenomic DNA fragments into pGX-1 vector containing green fluorescent protein. The library was screened for the clones expressing GFP on maltose induction using fluorescence activated cell sorter. One positive clone was isolated from the library that fluoresced in response to maltose. Sequence analysis of the positive clone revealed the presence of 2031 bp ORF designated as amy1, which encodes for periplasmic α-amylase. The ORF was found to be poorly expressed under its native malt promoter and hence the ORF was cloned and over expressed in Escherichia coli Rosetta using T7 expression system. The over expressed recombinant amylase AMY1 was purified to homogeneity by Ni–NTA chromatography. SDS-PAGE analysis of the purified enzyme revealed a molecular mass of 76.5 kDa. The purified enzyme also showed a clear band of starch hydrolysis on zymogram analysis.

Microbial Bioremediation: A Metagenomic Approach

Abstract: Microbial bioremediation serves as an alternative and effective strategy to remove toxic contaminants from a polluted environment. It could be achieved through the interaction of microbes with the toxic contaminants, which leads to immobilization, compartmentalization, and concentration of pollutants rather than their degradation and elimination from the environment. Bioremediation of the contaminated sites employing indigenous microbes is highly advantageous as it is ideally adapted to the environmental conditions prevailing at the site to be remediated. Traditional culture-based approaches have provided only limited information on the metabolic potential and the functional activity of the indigenous microbial communities living in the contaminated environment. Recent development of metagenomic approaches and advancement of high-throughput DNA sequencing technology provides insight into the total microbial community and in-depth knowledge of the metabolic capabilities of the indigenous microbial community prevailing in contaminated sites. Metagenomic approaches could address environmental issues by exploring the phenomenal resources of the uncultivable microorganisms. The present chapter describes the application of metagenomic strategies for better understanding of the indigenous microbial communities and their functional abilities to clean up toxic contaminants from polluted sites, which will provide new perspectives on environmental management.

Metal contamination and bioremediation of agricultural soils for food safety and sustainability

Abstract: Agricultural soil is a non-renewable natural resource that requires careful stewardship in order to achieve the United Nations’ Sustainable Development Goals However, industrial and agricultural activity is often detrimental to soil health and can distribute heavy metal(loid)s into the soil environment, with harmful effects on human and ecosystem health In this Review, we examine processes that can lead to the contamination of agricultural land with heavy metal(loid)s, which range from mine tailings runoff entering local irrigation channels to the atmospheric deposition of incinerator and coal-fired power-plant emissions We discuss the relationship between heavy metal(loid) biogeochemical transformations in the soil and their bioavailability We then review two biological solutions for remediation of contaminated agricultural land, plant-based remediation and microbial bioremediation, which offer cost-effective and sustainable alternatives to traditional physical or chemical remediation technologies Finally, we discuss how integrating these innovative technologies with profitable and sustainable land use could lead to green and sustainable remediation strategies, and conclude by identifying research challenges and future directions for the biological remediation of agricultural soils Contamination of agricultural soils by heavy metals and metalloids has severe consequences on human and ecosystem health This Review discusses the sources of heavy metal(loid) contamination, the mechanisms by which these contaminants interact with biological and geochemical soil elements, and plant-based and microorganism-based remediation strategies

Fermented Foods as a Dietary Source of Live Organisms

Abstract: The popularity of fermented foods and beverages is due to their enhanced shelf-life, safety, functionality, sensory, and nutritional properties. The latter includes the presence of bioactive molecules, vitamins, and other constituents present in the initial food substrates. Many fermented foods also contain live microorganisms that may improve gastrointestinal health and provide other health benefits, including lowering the risk of type two diabetes and cardiovascular disease. The number of organisms in fermented foods can vary significantly, depending on how products were manufactured and processed, as well as conditions and duration of storage. In this review, we surveyed published studies in which lactic acid and other relevant bacteria were enumerated from the most commonly consumed fermented foods, including cultured dairy products, cheese, fermented sausage, fermented vegetables, soy-fermented foods, and fermented cereal products. Most of the reported data were based on retail food samples, rather than experimentally produced products made on a laboratory scale. Results indicated that many of these fermented foods contained 105-7 lactic acid bacteria per mL or gram, although there was considerable variation based on region and sampling time. In general, cultured dairy products consistently contained higher levels, up to 109/mL or g. Although few specific recommendations for what constitutes a relevant dose exist, the findings from this survey revealed that many fermented foods are a good source of live lactic acid bacteria, including species that reportedly provide human health benefits

Interactions between Bacteria and Bile Salts in the Gastrointestinal and Hepatobiliary Tracts.

Abstract: Bile salts and bacteria have intricate relationships. The composition of the intestinal pool of bile salts is shaped by bacterial metabolism. In turn, bile salts play a role in intestinal homeostasis by controlling the size and the composition of the intestinal microbiota. As a consequence, alteration of the microbiome-bile salt homeostasis can play a role in hepatic and gastrointestinal pathological conditions. Intestinal bacteria use bile salts as environmental signals and in certain cases as nutrients and electron acceptors. However, bile salts are antibacterial compounds that disrupt bacterial membranes, denature proteins, chelate iron and calcium, cause oxidative damage to DNA, and control the expression of eukaryotic genes involved in host defense and immunity. Bacterial species adapted to the mammalian gut are able to endure the antibacterial activities of bile salts by multiple physiological adjustments that include remodeling of the cell envelope and activation of efflux systems and stress responses. Resistance to bile salts permits that certain bile-resistant pathogens can colonize the hepatobiliary tract, and an outstanding example is the chronic infection of the gall bladder by Salmonella enterica. A better understanding of the interactions between bacteria and bile salts may inspire novel therapeutic strategies for gastrointestinal and hepatobiliary diseases that involve microbiome alteration, as well as novel schemes against bacterial infections.

Genomics of microbial plasmids: classification and identification based on replication and transfer systems and host taxonomy.

Abstract: Plasmids are important “vehicles” for the communication of genetic information between bacteria. The exchange of plasmids transmits pathogenically and environmentally relevant traits to the host bacteria, promoting their rapid evolution and adaptation to various environments. Over the past six decades, a large number of plasmids have been identified and isolated from different microbes. With the revolution of sequencing technology, more than 4,600 complete sequences have been determined from plasmids found in bacteria, archaea, and eukaryotes. The classification of a wide variety of plasmids is not only important to understand their features, host ranges, and microbial evolution but is also necessary to effectively use them as genetic tools for microbial engineering. This review summarizes the current situation of the classification of fully sequenced plasmids based on their host taxonomy and their features of replication and conjugative transfer. The majority of the fully sequenced plasmids are found in bacteria in the Proteobacteria, Firmicutes, Spirochaetes, Actinobacteria, Cyanobacteria and Euryarcheota phyla, and key features of each phylum are included. Recent advances in the identification of novel types of plasmids and plasmid transfer by culture-independent methods using samples from natural environments are also discussed.