Seasonal composition and activity of sulfate-reducing prokaryotic communities in seagrass bed sediments

Aquatic Microbial Ecology

Joel E. Kostka¹  April C. Smith¹  Diane F. Yates¹  Richard Devereux¹ 

关键词: dsr gene;    Seagrass;    Sulfate reduction;    Sediment geochemistry;    Sulfate-reducing bacteria;   

DOI  :  10.3354/ame037183

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Sulfate-reducing prokaryotes (SRP) play a key role in the carbon and nutrient cycles of coastal marine, vegetated ecosystems; however, the interactions of SRP communities with aquatic plants remain little studied. The abundance, activity, andcommunity composition of SRP were studied in relation to sediment geochemical gradients and plant growth state in a Thalassia testudinum seagrass bed and in adjacent unvegetated areas. Geochemical analyses indicated significantly higherconcentrations of microbial respiration products in vegetated sediments during summer than during winter. Depth-integrated sulfate reduction rates were 3 to 5 times higher in vegetated (52.5 mmol m^-2 d^-1 in summer and 20.4to 26.5 mmol m^-2 d^-1 in winter) compared to unvegetated sediments (10.7 mmol m^-2 d^-1 in summer and 3.6 to 7.6 mmol m^-2 d^-1 in winter), and depth-integratedactivities further showed a strong correlation with seagrass biomass. Most probable number (MPN) counts of SRP were 10 times higher in vegetated compared to unvegetated sites in the summer during the period of maximum growth for seagrasses, whereas nodifference was observed for counts between sites during the winter. The community composition of SRP was determined using restriction fragment length polymorphism (RFLP) screening and amino acid sequence comparisons inferred from partial dissimilatorybisulfite reductase (dsrA and B) genes that were PCR-amplified and cloned from DNA extracted from sediment samples. The majority of unique DSR sequences were not affiliated with any known SRP group, and clustered at levels indicative of newSRP. Some DSR sequences grouped on the basis of originating from vegetated or unvegetated sediments, although the relationship did not appear to be strong. The diversity of SRP in seagrass bed sediments, as indicated by dsr analysis, was high anddid not appear to covary with the other environmental parameters tested. Our results indicate that seagrass growth state enhances the abundance and activity of SRP, while SRP community composition remains relatively stable across the environmentalparameters tested.

【 授权许可】

Unknown