Identification of marine bacteria collected from healthy and bleached Acropora sp. in Pasir Akar, Pulau Redang

Abstract

This study was conducted in Pasir Akar, Pulau Redang. The objectives of this study are to isolate and identify the types of bacteria present in healthy and bleached tissue of Acropora sp. Fragments of healthy and bleached Acropora formosa and A.nobilis corals were taken at the depth of l O m with the aids of scuba gear and brought back to the laboratory for further analysis and identification. Culture-based methods were applied to isolate the bacteria from the coral tissues and identified by referring to Bergey's Manual of Determinative Bacteriology. Overall, there were 23 types of bacteria that had been successfully isolated and identified. Aformosa was found to harbor 13 types of bacteria; four from healthy coral colony and nine from bleached coral colony. Meanwhile for A.nobilis, 10 types of bacteria were to associate with its tissue; six from healthy colony and four from bleached colony. Some examples of bacteria that had been successfully identified include Alcaligenes sp., Azotobacter sp., and Micrococcus sp. However, there is overlapping of bacteria existence where Pseudomonas sp. and Brochothrix sp. are inhabit both of Aformosa and A.nobilis. All of the bacteria were known to inhabit marine environment except Acetobacterium sp. and Caryophanon sp. About 62% of the bacteria are Gram-positive and 38% are Gram-negative. The most dominant groups are affiliated to y-proteobacteria class and Firmicutes which represent 33% of the total bacteria isolated respectively, and then followed by Actinobacteria (19%), a-proteobacteria (10%) and lastly b-proteobacteria (5%). Some of the bacteria may play important roles in the interaction of coral-bacteria such as nitrogen fixer and secrete antibiotic substances to xii protect their host, which were the corals itself. However, the overall roles played by these bacterial communities are still relatively unknown