Bacterial composition and spatiotemporal variation in sediments of Jiaozhou Bay, China

Abstract

Purpose Although coastal marine sediments harbor diverse bacteria with important ecological and environmental functions, a comprehensive view of their community characteristics is still lacking in typical environments along the China coast. We studied the diversity and composition of bacterial community in the sediment of Jiaozhou Bay and characterized their spatiotemporal patterns, aiming to analyze the effects of geographic heterogeneity, seasonal difference, anthropogenic activity, and eutrophication gradient on the bacterial ecology. Materials and methods Sixteen full-length bacterial 16S rRNA gene clone libraries were constructed from the sediment bacteria at four stations (A5, B2, D1, and D7) of Jiaozhou Bay over four seasons (February, May, August, and November). The bacterial diversity and community structure variation were analyzed. Results and discussion A total of 1088 16S rRNA gene sequences and 746 distinct operational taxonomic units (OTUs) (at 97 % sequence similarity level) were retrieved from the 16 clone libraries. Libraries of each sample revealed a high diversity, and a total of 17 bacterial phyla were identified.Bacteria lineages Proteobacteria (mostly γ-Proteobacteria and δ-Proteobacteria), Actinobacteria, Bacteroidetes, and Planctomycetes, which are commonly found in marine sediments, were the dominant divisions in our samples. Meanwhile, some uncommon phyla, such as Deinococcus-Thermus and Lentisphaerae, were also detected. Distinct spatial patterns and noticeable seasonal variations of bacteria community were observed, indicating that environmental heterogeneity in spatial variation other than in temporal variation may be more important in determining the bacterial communities. Most of the abundant OTUs were related to sequences retrieved from the heavy-metal-polluted environments, indicating that the Jiaozhou Bay might be influenced by pollution. Conclusions The bacterial communities in Jiaozhou Bay sediments are highly diverse. The four typical stations that we chose might experience different anthropogenic effects and eutrophication gradients, which shaped their bacterial community composition. The environment of Jiaozhou Bay may be under pressure exerted by multi-dimension anthropogenic activities. This study provided a novel insight into the bacterial community variations in Jiaozhou Bay, enriching knowledge about ecological bioindicators and mechanisms that maintain bacterial diversity and shape bacterial community composition.

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

“…Although Firmicutes was detected as a very minor phylum in Jiaozhou Bay sediments by the culture-independent method (Liu et al, 2015a ), Bacillus was found to be one of the predominant genera in the screened protease-producing strains from Jiaozhou Bay sediments in this study, confirming that Bacillus strains are easily cultivated protease-producing bacteria. Bacillus spp.…”

“…The culture-independent analysis (using the 16S rRNA gene clone library analysis) recently revealed that sediments of Jiaozhou Bay harbored extremely diverse bacteria belonging to 17 bacterial phyla, among which Proteobacteria (61.3% of the total sequences), especially Gammaproteobacteria (32.8%), constituted the most abundant group (Liu et al, 2015a ). Correspondingly, in our study, 71.2% of the total cultivated protease-producing strains (47 of 66 strains) are Gammaproteobacteria .…”

“…These stations with different water depths (4.0–12.8 m) are located in different regions of Jiaozhou Bay (Figure 1 , Table 1 ). Except for D1 station at the entrance of Jiaozhou Bay, other stations are in the inner bay: stations A5, C4, and Y1 are in the east coastal area of Jiaozhou Bay, the most hyper-nutrified and polluted part of the bay (Dang et al, 2009 , 2010a ); station A3 is in the mid-north of the bay; station B2 is in the mid-west and is the less-polluted station compared to the others (Dang et al, 2009 ; Liu et al, 2015a ). Replicate surface sediment subcore samples (5 cm depth) were taken aseptically using sterile 60-ml syringes (luer end removed) and stored in airtight sterile plastic bags at 4°C for screening bacterial strains or at −80°C for environmental analysis.…”

“…In the past four decades, with rapid socio-economic developments in the surrounding areas, Jiaozhou Bay has been greatly influenced by human activities and excess nutrient discharges from surrounding rivers, sewage processing plants, mariculture fields, and industrial and agricultural activities made parts of the bay hypernutrified (Liu et al, 2005 , 2010 ; Dai et al, 2007 ; Dang et al, 2009 ). Several studies have investigated the diversity and community structure variations in response to changes in environmental conditions of the total sediment bacteria or specific functional groups involved in the key steps of the nitrogen cycling in the eutrophied Jiaozhou Bay using molecular techniques (Dang et al, 2009 , 2010a , b ; Liu et al, 2015a ). But till now, there have been no report to investigate the diversity of protease-producing bacteria and their extracellular proteases in sediments of this eutrophic bay.…”

Spatial and temporal succession of bacterial communities in three artificial fishponds

“…Redundancy analysis and pRDA analyses showed that bacterial community composition was more influenced by pond isolation than by nutrients. Previous studies on bacterial communities in sediment environments have also reported that spatial variation is the most important factor in determining the bacterial community structure (Bowen, Crump, Deegan, & Hobbie, ; Liu, Hu et al, ). In sediment from aquaculture pond environments, habitat heterogeneity might be associated with slight differences in the farming process, and this may separate one bacterial community from another (Fan, Barry, et al, ).…”