Isolation and identification of microorganisms from high temperature seaweed beds and study on the characteristics of thermo and salt tolerances

Abstract:

[Objective] Microorganisms from high temperature seaweed beds on Kalianda Island of Indian Ocean were isolated, cultivated, and identified based on 16S rDNA sequences. Study on characteristics of thermo and salt tolerances of selected isolates were also carried on. [Methods] Samples of alga Sargasso sp., sediment and water from seaweed beds were collected. Using MGYTC medium, microorganisms from the samples were cultivated and purified at 55 °C and 30 °C, respectively. Species identification was determined based on 16S rDNA sequences and phylogenetic tree was built afterwards. Effects of culture temperature and salinity on bacterial growth were determined. [Results] A total of 12 strains belonged to four classes and nine genuses were obtained, and the maximum similarities were higher than 98% with known species. Two strains belonged to different genus of thermophilic actinomycetes, and two Bacillus strains obtained at 55 °C were thermophile. Laceyella sacchari and Bacillus thermoamylovorans can survive at the range of 0–90 salinity. Shewanella upenei, Shewanella algidipiscicola and Shewanella haliotis belonged to γ-Proteobacteria could grow at the temperature of 30 °C–55 °C. [Conclusion] The strains obtained had features of thermo and salt tolerances, or adaptability to wide temperature range, which were expected to be new resources in biotechnology field. The isolates of Tepidibacter formicigenes, Exiguobacterium profundum and Vibrio diabolicus had been originally reported from the deep-sea hydrothermal area, suggesting the internal relations of marine hot spring system and deep-sea hydrothermal environment.