Bacterial Community Profiling of Waters from Aquaculture and Non-aquaculture Sites within Taal Lake Ecosystem through 16S rDNA Analysis

Abstract

Background and Objectives: Inland water microbial communities are key players in the biogeochemical processes. However, many inland waters become polluted due to various anthropogenic practices. To determine the impact of aquaculture on microbial diversity in a lake ecosystem, the study determined and compared the bacterial composition of waters in aquaculture and non-aquaculture sites in Taal Lake using molecular techniques.

Methodology: Microbial DNA was extracted using the cetyl trimethylammonium bromide (CTAB) method. The DNA isolates were used as template for the amplification of bacterial 16S rDNA through nested polymerase chain reaction (PCR). The amplified 16S rDNA hypervariable regions were subjected to denaturing gradient gel electrophoresis (DGGE) for bacterial community profiling. Excised DGGE bands were sequenced and identified through BLAST analysis.

Results and Conclusion: The generated Dice similarity coefficient of 18.20 indicated low bacterial community similarity between aquaculture and non-aquaculture waters. This implies that the change in physicochemical parameters in aquaculture waters may cause a shift in the bacterial community composition allowing different bacterial populations to dominate in one site relative to the other site. Taal Lake aquaculture waters were found to harbor bacteria under the Proteobacteria and Actinobacteria groups, while non-aquaculture waters contained bacteria that are members of Proteobacteria, Actinobacteria, and Firmicutes. The presence of clinically-associated bacterial strains in both aquaculture and non-aquaculture sites in Taal lake poses a risk to fish and human health.