Rise of the dormant: Simulated disturbance improves culturable abundance, diversity, and functions of deep-sea bacteria of Central Indian Ocean Basin

Abstract

The abundance of baroduric bacteria from nine sediment cores (0-10 cm below sea floor) was examined for their response to simulated benthic disturbance in the Central Indian basin (CIB). While the total counts of bacteria decreased from 10 sup(9 ) to 10 sup(6) g sup(-1) dry wt sediment, the average retrievable counts (CFU-colony forming units) improved by two orders of magnitude, i.e., from 10 sup(2) to 10s sup(4) g sup(-1) dry wt sediment. The baroduric retrievable forms were dominated by Acinetobacter and Moraxella sp before the disturbance. After the disturbance the generic diversity was represented by Staphylococcus sp, Enterobacter sp, Micrococcus sp, Coryneforms sp, and Pseudomonas sp in addition to Acinetobacter. These observations were corroborated by changes in enzymatic activities of the retrievable bacteria, which could lead to changes in the biochemical characteristics of the sediment. Thus the simulated disturbance brought about an increase in culturable abundance, taxonomic and functional diversity of deep-sea sediment of the CIB.