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BACTERIAL DIVERSITY IN ANDAMAN SEA, THAILAND BY CULTURE-DEPENDENT AND CULTURE-INDEPENDENT METHODS.
Thailand is surrounded by Andaman Sea and Gulf of Thailand. As Thailand is located around an equator with hot and rainy climate, Thai marine comprise abundant microbial biodiversity. Yet, conventional or standard method cultural procedures could reveal < 1% of all microbiota due to limited capacity of the microorganismal growth under laboratory condition. Presently, the other > 99% of the microbiota could be revealed by culture-independent approach known metagenomics. This research utilized culture-dependent and culture-independent methods (metagenomics combined with pyrotagged 16S rDNA sequencing) to attain a complete picture of the true prokaryotic diversity of this environment, and better understand the ecosystem of bacteria and archaea in the southeast Andaman Sea off the west coast of Thailand. The seawater samples of two different distances from the Andaman coast: 08o56.004'N 98o05.857'E (PT) at 30-meter depth and 08o51.096'N 97o31.207'E (TC) on the surface and at 30, 100, 150-meter depth were investigated. The PT and TC sites had the seafloor depths of approximately 35 meters and 155 meters, respectively. The latter represents the farther seashore distance sample. The culture-dependent and culture-independent data demonstrated that the culture-dependent method provided far fewer numbers of isolates than by the culture-independent method, which could detect species that were missed by plating and also highlighted several uncultured bacteria. As discussed above, it is likely that bacteria may not grow well in laboratory culture because growth of a single bacterial clade in pure cultures destroys the complex relationships that occur in the natural environment. Comparative global analysis for prokaryotic structure helped disclose how the marine microbiota in this Southeast Andaman Sea water off the west coast of Thailand after the 2004 tsunami disaster were in relative to the others. Development of biodiscovery research will require innovative approaches to be developed to significantly improve culture methods. These should be based on the growing cultured dependent method, data produced by molecular and metagenomics approaches together. This study show different and additional findings upon culture-dependent and culture-independent techniques, and thus both might be used in complementary to yield a complete picture of the true microbiota of the environment. Moreover, the study showed metagenomics combined with NGS a high-throughput and rapid method to allow accessing the natural microbial diversity in a very powerful way.
Though the instrument, reagent and maintenance costs for NGS are high, this method became inexpensive when compared with the huge number of sequencing reads it provide. The cultured and uncultured databases of bacteria and archaea of these sites and depths worthed invaluable to marine scientist, microbiologist, and the others, helping to understand the true marine microbiota and their population structures representing the southeast Andaman See off the west coast of Thai shores. Subsequently, this knowledge would improve our understanding of the microbial diversity and ecosystem services for which bacteria are critical components. Bacterial diversity may also be useful for informing ecosystem-level conservation and management decisions.
