Microhabitat-differentiated distribution of culturable and antagonistic bacteria in marine ecosystem: Seawater as the original microbial provider

Abstract

Abstract: Due to the typical tropical climatic characteristics, the Xisha archipelago in the South China Sea has derived typical biological treasures, particularly culturable bacteria. Microbial resources in nature will be valuable resources for industrial application only after being culturable microorganisms. Herein, the global distribution of culturable and antagonistic bacteria against aquatic pathogenic vibrios, including Vibrios parahaemolyticus, Vibrios harveyi, Vibrios alginolyticus, Vibrios campbellii, and Vibrios owensii, in thirty-nine stations of the Xisha archipelago across four main microhabitats of sediment, seawater, corals, and marine organisms were investigated by cultivation-based strategies. Vibrio was the dominant genus (68.98%) among the culturable bacteria, followed by Pseudoalteromonas (9.36%) and Alteromonas (4.91%). Only four targeted antagonistic strains with an antagonistic specificity of a certain Vibrio were obtained, namely the strains of SP52, C219 and W198, which provided a new insight of precise disease prevention/treatment by further revealing the targeted antagonistic mechanism. The correlations between the abundance of culturable bacteria and environmental factors in the whole Xisha archipelago and four microhabitats showed that salinity as the main factor significantly affected the distribution of 6 microbial genera, while total inorganic nitrogen (TIN), total carbon (TC), and PO43− significantly related to 3 genera, 2 genera, and 1 genus, respectively. Importantly, we found that microhabitat discrepancy rather than distance discrepancy of environmental factors made a greater contribution to the distribution of culturable bacteria and antagonistic bacteria and the capability of antagonistic bacteria, which was emphasized as an important factor in shaping bacterial communities. Additionally, seawater was the original microbial provider of other microhabitats in the marine ecosystem, which was the opposite of the terrestrial ecosystem in that the soil is the original microbial provider.