Effect of H₂S on heterotrophic substrate uptake, extracellular enzyme activity and growth of brackish water bacteria

• Published in: Marine ecology. Progress series (Halstenbek) 1990, Vol.64 (1/2), p.157-167
• Main Authors: Hoppe, H. G., Gocke, K., Kuparinen, J.
• Format: Article
• Language: English
• Subjects: Anaerobic conditions; Bacteria; Bacterial biomass; Brackish water; Enzyme activity; Fresh water; Oxygen; Sea water; Sediments; Surface water
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps064157

In some parts of the Baltic Sea, establishment of anoxia, H₂S accumulation and reaeration of the water column are common processes which have a bearing on the heterotrophic microbial community. The influence of these conditions on natural aerobic bacteria populations was studied in 24 h batch cultures. Measured parameters were: saprophyte number and total number of bacteria, active bacteria (leucine microautoradiography), heterotrophic substrate uptake (¹⁴C labelled glucose, leucine, lactate) extracellular enzyme activity (β-glucosidase, peptidase) and growth of bacteria (³H-methyl thymidine incorporation). Anoxia established by N₂ had a minor effect on these parameters and values approximated those from the oxic control within the incubation period. Addition of H₂S led immediately to a strong but variable reduction in all the activity measurements and recovery was weak when H₂S conditions were maintained over the experimental period. Re-aeration after 12 h of H₂S incubation caused a progressive increase of the activity measurements which then by far exceeded those from the continuously oxic control. An exception was peptidase, which recovered only slowly after H₂S depletion. Short-term application of H₂S caused clear changes in the metabolic and community structure of the originally aerobic bacterial population, which were also documented by a reduction of the spectrum of morphological cell characters. Cells which survived H₂S stress developed vigorously fkak after H₂S depletion. Values of bacterial production calculated from increases in active bacterial numbers and from thymidine uptake showed the same tendency; however, their absolute values differed considerably. This discrepancy may indicate that after H₂S stress many of the surviving cells were reactivated, but only a fraction of these started reproduction.