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Title: Role of microbial aggregation in biofilm formation by bacterial strains isolated from offshore finfish culture environment
Authors: Saravanan, N.
Verma, Pankaj
Mol, V. P. Limna
Kumar, R. Sendhil
Somasundaram, S. T.
Dharani, G.
Kirubagaran, R.
Keywords: Biofilm;Microcolony;Autoaggregation;Coaggregation;Growth phase
Issue Date: Nov-2014
Publisher: NISCAIR-CSIR, India
Abstract: Biofilm, the complex aggregation of microbes encased in a multifaceted matrix, is a very important module of marine biofouling. The biofilm formation is a sequential process involving transport of microbes to a surface, initial attachment, formation of microcolonies and biofilm maturation. Higher incidence of microcolonies, formed by autoaggregation as well as coaggregation, leads to enhanced biofilm formation. The present study was undertaken to elucidate the correlation between microbial aggregation and biofilm formation by marine bacteria isolated from the proximity of an offshore finfish cage. Seven bacterial strains were isolated from High Density Poly Ethylene (HDPE) test coupons. Qualitative analysis of auto and coaggregation was done using visual aggregation assay, followed by light microscopic observation for further confirmation. Quantitative analysis of aggregation was undertaken using Spectrophotometric assay. Aggregation was monitored for bacterial cultures in lag, log and stationary phases. The results indicated that the strain Oceanimonas smirnovii (NIOT-bflm-S10) exhibited maximum autoaggregation during lag and log phase, while Salinicoccus roseus (NIOT-bflm-S12) exhibited maximum autoaggregation during stationary phase. In case of coaggregation, O. smirnovii (NIOT-bflm-S10)–S. roseus (NIOT-bflm-S12), S. roseus (NIOT-bflm-S12) – Halomonas pacifica (NIOT-bflm-S13) and Pseudogracilibacillus auburnensis (NIOT-bflm-S3) – O. smirnovii (NIOT-bflm-S10) exhibited maximum aggregation index during lag, log and stationary phases, respectively. Subsequently, O. smirnovii exhibited maximum biofilm formation of 0.23, 0.26 and 0.42 (OD 595nm) after 24, 48 and 72 hours of incubation, respectively. In case of paired bacterial strains, maximum biofilm formation was exhibited by O. smirnovii – S. roseus after 24 (0.450), 48 (0.370) and 72 hours (0.560) of incubation. Thus, factors responsible for microbial aggregation, an immediate phenomena occurring in less than an hour of contact, would be a better target for inhibiting biofilm formation. The antifouling agent can be designed in such a way as to prevent / disrupt the initial microbial aggregation.
Page(s): 2118-2129
ISSN: 0975-1033 (Online); 0379-5136 (Print)
Appears in Collections:IJMS Vol.43(11) [November 2014]

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