Bacterial production, glucosidase activity and particle-associated carbohydrates in Dona Paula bay, west coast of India

• Main Authors: Bhaskar, P.V, Bhosle, N.B
• Format: Journal Article
• Language: English
• Published: Elsevier 2008
• Subjects: enzymatic activity; microorganisms; particulate organic carbon; polymerization

Size-fractionated bacterial production, abundance and Alpha - and Beta - glucosidase enzyme activities were studied with respect to changes in hydrography, total suspended matter (TSM), chlorophyll a, particulate organic carbon and nitrogen ratio (POC:PON), 1.5 M NaCl-soluble and 10 mM EDTA-soluble carbohydrates (Sal-PCHO and CPCHO) and transparent exopolymeric particles (TEP) in the surface waters from July 1999-2000 at a shallow coastal station in Dona Paula Bay, west coast of India. The bulk of the total bacterial production and glucosidase activity were associated with particles (75% and more than 80%, respectively). Total bacterial production was linearly correlated to chlorophyll a (r = 0.513; p less than 0.05) whereas enzyme activity was significantly correlated to TSM (Alpha glucosidase: r = 0.721 (p less than 0.001); Beta -glucosidase: r = 0.596 (p less than 0.01)). Both Alpha-glucosidase (r = 0.514; p less than 0.05) and Beta - glucosidase enzymes (r = 0.598; p less than 0.01) appeared to be involved in the degradation of CPCHO and Sal PCHO, respectively. Changes in Alpha -glucosidase / Beta glucosidase ratios highlighted the varying composition of particulate organic matter. The bacterial uptake of sup 14(C) - labeled bacterial extracellular carbohydrate measured over 11 days showed a strong linear correlation between sup 14(C) - uptake and bacterial production using tritiated thymidine. The turnover rate of sup 14 (C) - labeled carbohydrate - C was 0.52 d sup(-1), higher than the estimated annual mean potential carbohydrate carbon turnover rate of 0.33 + or - 0.2 d sup(-1). Our study suggests that carbohydrates derived from sediments may serve as an important alternative carbon source sustaining the bacterial carbon demand in the surface waters of Dona Paula Bay.