Effects of Grazing on Bacteria-Mediated Corrosion of Metals in Seawater
Final rept. Aug 1983-Aug 1985
VIRGINIA UNIV CHARLOTTESVILLE DEPT OF ENVIRONMENTAL SCIENCES
Pagination or Media Count:
Metal surfaces were allowed to become colonized by estuarine bacteria, after which half the samples were subjected to grazing for several days by washed cultures of protozoa. Samples from grazed and non-grazed metal stubs were examined with epifluorescent microscopy for numbers of bacteria on the surfaces, and an analysis of variance test was performed on data to determine significant differences. Bacterial activities on the surfaces of stainless steel 316 in the presence and absence of grazing protozoa was assessed by trapping 14CO2 metabolized from 14C-glutamic acid in heterotrophic uptake experiments. Appropriate controls were established to account for respiration from residual bacteria remaining with washed protozoa. Data were analyzed by an analysis of variance test. Results showed that grazing significantly increased both the numbers and metabolic activity of bacteria on metal surfaces. Reasons for such results are discussed. Although results imply that grazing protozoa can indirectly influence corrosion rates, there probably would be no point in pursuing it further with a laboratory approach for reasons discussed in the report. The project provided a foundation for future in situ studies, and the data are being prepared for publication.
- Properties of Metals and Alloys