Pathogenic Bacterial Strains from a Pristine Mangrove Ecosystem - Virulence Determination through Biochemical Fingerprinting

Abstract

Global health scenario is constrained by the emergence of novel, mutated, antibiotic-resistant highly virulent microbes, which impair human health and results in increased mortality rates. Among these pathogens water borne bacteria are the most dominant. Indiscriminate discharge of untreated waste water from households, industries and hospitals, turns natural water resources into reservoirs of potential pathogens. In this study, four pathogenic strains of bacteria were isolated, characterized and identified from the water samples collected from the mangrove ecosystem of Poovar, South Kerala, India. The bacterial colonies were isolated by serial dilution and spread plating. Morphologically distinct bacterial colonies were propagated in pure culture for biochemical and molecular characterization. Two Gram positive and two Gram negative pathogenic bacteria were  isolated and subjected to substrate utilization, enzyme secretion, acidification and antibiotic resistance tests as per the “Bergey’s Manual of Determinative Bacteriology”. The metabolic fingerprints of the isolates confirmed their pathogenicity and indicated the biochemical pathways that have evolved in these isolates, for virulence determination and host specific invasion. For precise taxon identification, the 16S rRNA sequences of the isolates were elucidated and aligned for homology with the standard sequences of NCBI GenBank through BLAST analysis. Based on the morphological, biochemical and molecular characteristics, the individual isolates were identified as Kocuria kristinae, Granulicatella elegans, Acinetobacter lwoffii and Acinetobacter baumannii. The presence and load of such highly virulent pathogenic strains of bacteria in natural ecosystems like the mangroves are alarming, since mangroves are the repositories that replenish the aqua fauna which serves the health and wealth of global mankind. The ability of the pathogenic microbes to survive in the highly fluctuating mangrove ecosystem, when read in conjunction with the threat of antibiotic resistance, horizontal gene transfer, co-evolution and guided evolution, indicate multiplied risk magnitude in public health and hence, we suggest that the environmental quality of the mangroves must be regularly monitored in order to avoid future health hazards.