Year: 1984
Type: dissertation
Abstract: Fermentation was investigated in a low sulfate hot spring microbial mat (Octopus Spring) according to current models on anaerobic decomposition.The mat was studied to determine what fermentation products accumulated, where in the mat they accumulated, and what factors affected their accumulation.Mat samples were incubated under dark anaerobic conditions to measure accumulation of fermentation products.Acetate and propionate (ca.3:1) were the major products to accumulate in a 55°,C mat.Other products accumulated to a much lesser extent.Incubation of mat samples of varying thickness showed that fermentation occurred in the top 4mm of the mat.This has interesting implications for fermentative organisms in the mat due to the diurnal changes in mat oxygen concentrations.Fermentation measured in mat samples collected at various temperatures (50°,-70°C) showed acetate and propionate to be the major accumulation products.According to the interspecies hydrogen transfer model, the hydrogen concentration in a system affects the types of fermentation products produced.At a 65° C site, with natural high hydrogen levels, and at a 55°C site, with active methanogenesis, fermentation product accumulation was compared.There was a greater ratio of reduced fermentation products to acetate, with the exception of propionate, at 65°C.Ethanol accumulated at the 65°C site, as did lactate, though to a lesser extent.Artificial induction of an elevated hydrogen environment with the addition of 2-bromoethanesulfonic acid to 55°C mat samples only produced a substantial difference in the ratio of acetate to ethanol.Mat samples incubated in the light had less acetate accumulation than corresponding samples incubated in the dark.This might be due to inhibition of product formation by photosynthetically-derived oxygen or to photoincorporation of fermentation products.A heterotrophic potential experiment showed that acetate, lactate, and ethanol had the greatest potential for uptake by the microbial population at a 65°C site.These results correlate with the lack of propionate accumulation at 65°C (propionate had the least potential for uptake at 65°C of the compounds tested), and with the accumulation of ethanol.The results also point out that placing importance on fermentation products by their accumulation data alone may be misleading.
Author: Karen L. Anderson
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W269154435