Dynamic Changes in Bacterial Population and Corresponding Exoenzyme Activity in Response to a Tropical Phytoplankton BloomChattonella marina

摘要

The raphidophyteChattonella marina(Subrahmanyan) Hara & Chihara bloom which causes lethal effects on marine ecosystem has been reported intermittently from Indian waters. In the present study, periodic samplings were made in aChattonella marinabloom area, off Mahe, on 27 and 29 October and 1 November 2011 (in different phases of the bloom) to assess the associated bacterial population and their exoenzyme activity. Microbial community composition ofChattonella marinabloom revealed a twentyfold increase in bacterial load over the nonbloom area. The bacterial genera,Micrococcus,Flavobacterium,Vibrio, andPseudomonas, increased significantly during the declining phase of the bloom. An assessment of the extracellular enzyme production also showed a marked increase in percentage of bacterial strains, potent in protease production, suggesting the possible role of proteolytic bacteria in bloom crash. This study reveals the bacterial community succession during the bloom and indicates that bacteria play an important role in bloom regulation.