Isolation and Characterization of Biofilm Producing Bacteria from Water Treatment Tank

Abstract

Biofilm is a community of bacteria and other microorganisms, which provides various advantages like nutrition, protection from host defences, etc. to name a fewHowever, biofilm is the main cause of the increase in antibiotic resistant microorganisms. Development of biofilms occurring on the inner surface of storage vessels offers a suitable medium for the growth of microorganisms and consequently contributes to the deterioration of treated drinking water quality. Biofilm formers secrete enzymes into the extracellular space to hydrolyze macromolecules into constituents that can be imported for microbial nutrition. The present study aims at the screening, isolation and characterization of biofilm producing bacteria from water treatment tanks using tube test, plate assay and ELISA technique. The 12 predominant isolated bacterial colonies were further studied for the presence of extracellular enzymes which are responsible for their growth and biofilm formation. Differential plate assay techniques were used for the qualitative detection of exoenzymes. Seven out of twelve bacterial isolates showed positive results for biofilm formation in tube assay and furthermore, was confirmed by ELISA plate assay. MTT assay was also performed to check for the cell viability. The potential strains were identified using the standard morphological and biochemical tests. From the obtained results it can be concluded that the exoenzyme activity is not solely mediated by community composition, but possibly influenced by bacterial communication, which is known to regulate such pathways in many bacteria.