Human population is rapidly accelerating because of which scientists are focusing to ensure food security to meet with demands. This situation is leading towards rapid amplification in aqua farming globally specifically in Asia. But, aquaculture industry has left some hazardous impacts on environment through pollution of ground and surface waters by means of waste matter discharge1,2. To cope with this situation; “Biofloc technology” (BFT) has attained the attention which is an efficient aquaculture system because it has the capability of biofloc to recycle the nutrients in the culture pond3. This target is achieved through elevated ratio of carbon to nitrogen (C:N) in the water by adding external carbon sources including molasses or starch to arouse heterotrophic bacterial growth which converts ammonia into microbial biomass4.
“Biofloc” is composed of various microorganisms such as bacteria, fungi, microalgae, protozoan and rotifers as well as organic matter such as faeces and unused feed5. Bacteria are considered as chief constituent of biofloc that produce biopolymer substances (Extracellular Polymeric Substance (EPS) to flocculate cells, suspended and colloidal solids6. But unfortunately, microbial composition in biofloc is still under discussion7,8. Therefore, ample knowledge is essential on microbiological aspects chiefly in microbial communities in biofloc which is significant for the effectual biofloc technology.
Accordingly; Nor Azman Kasan and colleagues designed an experiment to isolate and recognize bacteria from biofloc through 16S rDNA sequences analysis to produce inoculums for rapid formation of biofloc. In this investigation, scientists isolated the bacterial communities during 0, 30 and 70 days of culture (DOC) of L. vannamei grow-out ponds. Identification process was carried out by phenotypic and 16S rDNA sequences analysis. Afterwards, assessment of phylogenetic inter linkage between isolated bacteria was done through phylogenetic tree analysis. Furthermore; one-way analysis of variance (ANOVA) was employed to compare the differences of microbial communities at each DOC.
During this research, scientists lucratively identified the 9 species of bioflocculant-producing bacteria including Halomonas venusta, H. aquamarina, Vibrio parahaemolyticus, Bacillus infantis, B. cereus, B. safensis, Nitratireductor aquimarinus, Providencia vermicola and Pseudoalteromonas sp. from biofloc of shrimp pond via 16S rDNA sequences analysis. Moreover, occurrence of heterotrophic bacteria genera including Halomonas sp. and Bacillus sp., in biofloc exhibited great potential to be employed as inoculums for rapid formation of biofloc towards sustainable aqua farming practices.
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18 August, 2019