Recent literature has suggested a novel symbiotic relationship between bacteriophage and metazoan host that provides antimicrobial defense protecting mucosal surface by binding to host matrix mucin glycoproteins. Here, we isolated and studied different bacteriophages that specifically interact with human extracellular matrix molecules such as fibronectin, gelatin, heparin and demonstrated their potency for protection to host against microbial infections. We showed that subpopulations of bacteriophages that work against clinical isolates of
Escherichia coli
can bind to pure gelatin, fibronectin and heparin and reduced bacterial load in human colon cell line HT29. The bacteriophages were characterized with respect to their genome sizes, melting curve patterns and host tropism (cross-reactivity with different hosts). Since, the bacteriophages are non-toxic to the host and can effectively reduce bacterial load in HT29 cell line their therapeutic potency against bacterial infection could be explored.
We report the draft genome sequence of Escherichia coli ASBT-1, a representative of E. coli sequence type 155 (ST155), obtained from India. Considering the known wide variety of pathogenic and antibiotic resistance potentials, this strain should be of great interest for detailed comparative genomic analysis.
Robust control of pathogens in sewage facilitates safe reuse of wastewater rich in valuable nutrients for potential valorization through biological means. Aspergillus niger is widely reported in bioremediation of wastewater but studies on control of enteric pathogens in sewage are very sparse. So, this study aimed at exploring the antibacterial and nematicidal activity of A. niger culture filtrate (ACF). Antibacterial activity of ACF on enteric pathogens (Klebsiella pneumoniae, Pseudomonas aeruginosa, Vibrio cholerae, Salmonella enterica, Shigella dysenteriae, Escherichia coli, Staphylococcus aureus, Klebsiella variicola) was determined by spectrophotometric growth analysis, resazurin based viability assay and biofilm formation assay. ACF showed inhibition against all enteric pathogens except Pseudomonas aeruginosa. Nematicidal studies on Caenorhabditis elegans showed 85% egg hatch inhibition and 52% mortality of L1 larvae. Sewage treatment with ACF at 1:1 (v/v) showed 2–3 log reduction in coliforms, Klebsiella, Shigella, Salmonella, S. aureus and Vibrio except Pseudomonas, indicating significant alteration of complex microbial dynamics in wastewater. Application of ACF can potentially be used as a robust biocontrol strategy against infectious microbes in wastewater and subsequent valorization by cultivating beneficial Pseudomonas.
Bacterial pathogens are fostered in and transmitted through wastewater. Hence, monitoring their impact on sanitation and hygiene is imperative. As part of the monitoring process, culture-based methodologies are primarily used, which centre on the use of selective and differential media. Media available today are, at best, difficult to formulate and, at worst, prohibitively expensive. To address this lacuna, the study proposes a selective and differential medium for Klebsiella spp. Klebsiella blue agar (KBA) is completely selective against selected gram-positive bacteria (Bacillus spp., Staphylococcus aureus) and a few gram-negative bacteria (Acinetobacter baumanii, Serratia marcescens). On the other hand, it supports the growth of the chosen members of the Klebsiella pneumoniae species-complex with a characteristic green colouration. Methylene blue, tryptophan, and bile salt make up the selective components of KBA. Moreover, methylene blue, 0.6% NaCl, and glycerol render it differential. KBA was more selective than HiCrome™ Klebsiella Selective Agar Base (KSA) in replica plating experiments. KBA promoted only 157 CFUs against 209 CFUs in KSA when stamped with 253 CFUs grown on LB. The colonies so isolated were predominantly Klebsiella spp., on identification through colony polymerase chain reaction. Moreover, the differential nature of KBA distinguished Klebsiella aerogenes from other species. On the contrary, KSA lodged colonies indistinguishable from each other and Klebsiella spp. Due to its ease of formulation, high selectivity, differential nature, and cost-effective composition, KBA is a viable option for the routine culture of Klebsiella spp. in environmental and clinical settings.
Key points
• Formulated a novel selective and differential media for Klebsiella spp., named Klebsiella Blue agar
• Facile formulation methodology
• Can be employed to isolate Klebsiella spp. from complex sources such as wastewater
We report the draft genome sequence of a putative probiotic strain, Lactobacillus fermentum ASBT-2, isolated from domestic sewage in Kerala, India. The strain showed probiotic properties (tolerance to low pH and bile salts, binding to host matrix) and reduced the coliform count by 90% in a biofilter used to treat wastewater.
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