Biofilm Acts as a Microenvironment for Plankton‐Associated Vibrio cholerae in the Aquatic Environment of Bangladesh

Abstract

Vibrio cholerae O1 causes Asiatic cholera and has been regarded as a member of a group of organisms whose major habitats are aquatic ecosystems (7,21,22). V. cholerae is currently classified into 206 "O" serogroups based on the heat stable somatic "O" antigen (43,49). Only V. cholerae O1 and O139 have been found to be associated with epidemic cholera. V. cholerae non-O1, non-O139 serogroups are ubiquitous in the aquatic environment and recognized as causative agents of sporadic and localized outbreaks (6, 42). When V. cholerae is not wreaking havoc in the human intestine, it may be found in diverse aquatic environment such as estuaries, rivers, ponds, etc. (8, 23). Adhesion to surfaces both in the human intestine and in the aquatic environment plays an important role in V. cholerae's success as a pathogen and an environmental organism. In the aquatic environment, V. cholerae can survive either as free-living planktonic organisms in the water column, attached to a variety of abiotic surfaces or associated with phytoplankton and zooplankton (14,(18)(19)(20).Bacteria attach to surfaces of this kind as widely-separated individuals, small colonial aggregates or confluent biofilm communities characterized by interactions between community members and a three dimensional architecture that provides channels through which nutrients and metabolic by-products circulate. Biofilms that form in multi-species habitats can be composed either of a single strain or of multiple strains or species (10). Abstract: The role of biofilm as a microenvironment of plankton-associated Vibrio cholerae was investigated using plexiglass as a bait. A total of 72 biofilm samples were tested using culture, direct fluorescent antibody (DFA) and molecular techniques following standard procedures. Culturable V. cholerae (smooth and rugose variants) were isolated from 33% of the samples. V. cholerae O1 were detected by FA technique throughout the year except April and June. All V. cholerae O1 isolates were positive for tcpA, ctxA and ace genes while V. cholerae non-O1, non-O139 isolates lacked these genes. V. cholerae O1 (both Inaba and Ogawa) strains had identical ribotype pattern (R1), but V. cholerae non-O1, non-O139 had different ribotype patterns. All V. cholerae O1 strains were resistant to vibrio-static compound (O/129). All V. cholerae O1 except one were resistant to trimethoprime-sulphamethoxazole, streptomycin, nalidixic acid and furazolidone but sensitive to ciprofloxacin, and tetracycline. This study indicates that plexiglass can act as a bait to form biofilm, a microenvironment that provides shelter for plankton containing V. cholerae in the aquatic environment of Bangladesh. Biofilm Acts as a Microenvironment for

Genetic relationship between clinical and environmental Vibrio cholerae isolates in Tanzania: A comparison using repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) fingerprinting approach

“…The reemergence of cholera is presenting unprecedented challenges and scientists have for long time questioned how V. cholerae could seemingly disappear-undetected in water samples; with no new cases reported, and then almost spontaneously arise again. Exactly what awakens the bacterium from their dormant state is unknown, but it is thought to involve a combination of different factors, such as water temperature, water salinity, nutrients and phytoplankton biomass that provide the "right" conditions (Islam et al, 2007). Climatic factors have also been shown to be significant in cholera epidemics (Lobitz et al, 2000;Lipp et al, 2002;Fernández et al, 2009) due to the fact that the historical context of the disease has a close link to specific seasons and biogeographical zones.…”

Biofilms in water, its role and impact in human disease transmission

“…Production of alginate, an exopolysaccharide present as an extracellular matrix in Pseudomonas aeruginosa biofilm, is induced upon the contact of the cells with a surface. Laboratory microcosm experiments suggest cells of V. cholerae form biofilms on biotic and abiotic surfaces, thereby protecting themselves with this exopolymer barrier [5].…”

Structural Basis for Biofilm Formation via the Vibrio cholerae Matrix Protein RbmA

“…One such pathogen is Vibrio cholerae, the causative agent of the severe diarrheal disease cholera (3). V. cholerae is autochthonous to coastal and estuarine environments where it resides in a free-living state or in a biofilm state (4)(5)(6)(7)(8). The pathogen is transmitted to humans by ingestion of contaminated food and water.…”