Temporal and Spatial Distribution of Sulfate Reducing Bacteria in Shrimp Culture Pond Sediment

Abstract

Sulfate reduction, a key process in aquatic sediments is carried out by a group of anaerobic microorganism called sulfate reducing bacteria (SRB). High numbers of sulphate reducers in shrimp aquaculture pond sediment deteriorates the soil and water quality, causing physiological stress, thereby reducing the immunity of cultured animal. An attempt was made to evaluate the temporal and spatial distribution of SRB horizontally at different locations viz., water pumping area (WPA), sluice gate (SG) and pond center (PC), and vertically from sediment water interface to 10 cm depth in Pacific white shrimp, Penaeus vannamei culture ponds. Physico-chemical characteristics of water and soil were correlated with the number of SRB. Distribution of SRB was significantly higher (p ≤ 0.05) in the pond sediment nearer to SG (874 MPN/g), followed by PC (272 MPN/g) and WPA (99 MPN/g) and at sediment water interface (751 MPN/g) compared to 10 cm depth (114 MPN/g) of pond profile. Factors like dissolved oxygen and soil redox potential (oxidation to reduction scale), and organic carbon content in soil had a significant negative and positive correlation with SRB numbers. Phylogenetic relationship of SRB targeting SRB groups showed the presence of Desulfonema, Desulfosarcina, Desulfatibacilum, Desulfobotulus, Desulfomicrobium, Desulfococcus, Desulfovibrio and Clostridium genera in shrimp culture pond sediments.