Biofilms colonizing on artificial as well as natural surfaces is a fundamental step in the aquatic ecosystem that further recruits macrofoulers and add up community complexity. In the formation of biofilm, prokaryotes are initial colonizers, wherein, bacteria are prominent. Detrimental consequences of biofouling have been widely examined in various area including ship hulls, heat exchangers and inside the condenser tube of power plant, pipelines, mechanical blockage, immature replacement of equipments and/or effect on uses of structural components. The attached bacterial communities on any artificial substrates are very heterogeneous, dynamic and dissimilar to planktonic communities present in surrounding water column. The attachment of specific microbial species is influenced by biotic and abiotic factors of an ecosystem. Identifying fundamental components and factors that influence the community shape of microfouling is a longstanding ecological concern that rather scarce hitherto. The present investigation was carried out in the vicinity of a coastal nuclear power plant, located at Kudankulam, Southern coastal area of India. A considerable endeavor was undertaken to identify and understand the major bacterial lineages involved in biofilm formation and how far their abundance is different from seawater community. To gain more insight into this, both natural biofilm (formed on artificial surfaces) and surrounding seawater at the same time were collected and bacterial diversity was assessed through high throughput Next generation sequencing. A total of ? 1 million Illumina PE reads were generated by targeting the V3-V4 hypervariable regions of 16S rDNA using metagenomic DNA as template. High-quality sequences were taxonomically allocated at various levels and observed that Proteobacteria preponderant both communities (64-92%), particularly Gammaproteobacteria, accounted for >85% in natural biofilm. Three bacterial families viz. Vibrionaceae, Alteromonadaceae, and Pseudoalteromonadaceae dominated the natural biofilm community and cumulatively constituted for >73% of the total community. Collectively, data obtained here are attestant for species sorting process that occur during initial assembly of bacterial community in marine ecosystem. Such studies provide a base to understand the factors that influence the biofilm formation and critical to develop/improve a long-term and efficient strategy to control biofouling.