Diversity of cultivable protease-producing bacteria in sediments of Jiaozhou Bay, China

Abstract

Although protease-producing bacteria are key players in the degradation of organic nitrogen and essential for the nitrogen recycling in marine sediments, diversity of both these bacteria and their extracellular proteases is still largely unknown. This study investigated the diversity of the cultivable protease-producing bacteria and their extracellular proteases in the sediments of the eutrophied Jiaozhou Bay, China through phylogenetic analysis and protease inhibitor tests. The abundance of the cultivable protease-producing bacteria was up to 104 cells/g in all six sediment samples. The cultivated protease-producing bacteria mostly belonged to the phyla Proteobacteria and Firmicutes with the predominant genera being Photobacterium (39.4%), Bacillus (25.8%), and Vibrio (19.7%). Protease inhibitor tests revealed that extracellular proteases secreted by the bacteria were mainly serine proteases and/or metalloproteases with relatively low proportions of cysteine proteases. This study represents the first comprehensive analysis on the diversity of protease-producing bacteria and their extracellular proteases in sediments of a eutrophic bay.

Characterization of a New S8 serine Protease from Marine Sedimentary Photobacterium sp. A5–7 and the Function of Its Protease-Associated Domain

“…Photobacterium sp. A5–7 was isolated from a marine sediment sample from the A5 station site in Jiaozhou Bay, China, where the depth, temperature, pH and C/N ration were 5.9 m, 24.7°C, 8.11 and 7.0, respectively (Zhang et al, 2015). P57 had low optimal temperature (40°C), and low thermostability at moderate temperatures (unstable at temperatures higher than 30°C), and displayed high activity at alkaline pH (pH 7.0–9.0) with the optimum pH of 8.0.…”

“…Among the strains, Photobacterium sp. A5–7 had the highest protease activity, which was isolated from the sediment sample from the A5 station site where the depth, temperature, pH and carbon/nitrogen ratio were 5.9 m, 24.7°C, 8.11 and 7.0, respectively (Zhang et al, 2015). In this study, we aimed to purify and characterize the protease secreted by Photobacterium sp.…”

A modified culture medium for improved isolation of marine vibrios

“…The use of improved culture media would be useful in environmental studies, as well. In fact, the interest toward the genus Vibrio (not only pathogenic species) in marine environments is being increased in last years, due not only to their ecological role and impact on natural ecosystems (Herbert, ; Zhang et al, ), but also to their dynamics in aquatic environments in response to climate changes (Vezzulli et al, ). Thus, reliable culture media with the maximum recovery efficiency are useful to assess the presence of vibrios by cultivation, as well as for their isolation.…”

“…Data herein reported clearly indicate that some marine vibrios are unable to grow on selective culture media such as standard TCBS agar, and that they require adjusted medium composition for a successful isolation. In fact, the use of a modified TCBS medium greatly (Herbert, 1999;Zhang et al, 2015), but also to their dynamics in aquatic environments in response to climate changes (Vezzulli et al, 2012(Vezzulli et al, , 2016. Thus, reliable culture media with the maximum recovery efficiency are useful to assess the presence of vibrios by cultivation, as well as for their isolation.…”

“…Moreover, besides their biotechnological potential, including biomedical applications (Salamone et al, 2015), the interest toward the genus Vibrio (not only pathogenic species) in marine environments has increased in last years, due not only to their ecological role in natural ecosystems (Herbert, 1999;Zhang et al, 2015) but also to their dynamics in aquatic environments in response to climate changes (Narracci, Acquaviva, & Cavallo, 2014;Vezzulli et al, 2012Vezzulli et al, , 2016.…”