Abstract
The study had aimed to characterize the production of hydrogen gases by anaerobic bacteria. One isolate was found in sheep ruminal fluid and four isolates were obtained from the activated sludge. These isolates were identified by microscopic methods and by rRNA sequences. One ruminal bacterium was identified as Escherichia coli, and it was found that these isolates from activated sludge were related to Clostridium botulinum, C. perfringens and C. difficile. One strain could not be assigned to any species but was similar to C. botulinum. Growth and production of the metabolic gases with molasses as sole carbon source were measured during the anaerobic cultivation by Micro-Oxymax (Columbus Instruments, Columbus, OH, U.S.A.) gas analyzer. One of the most available saccharidic waste products is molasses. The growth on molasses as carbon source was done to test the production of H2. It was found that all tested Clostridium isolates (AK 1-4, AK 1-5, AK 1-9 and AK 1-12) and E. coli isolate (No 2- 24) had utilized molasses as carbon source monitored by production of CO2 gas. All these strains produced H2 gas, and CO gas in concentration range 102 μmol L–1, and H2S gas in concentrations lower by one order of magnitude. Kinetics of evolution of these gases was different suggesting that they are produced by independent processes. Results show that metabolic gases are produced mainly in the exponential phase of growth.
Highlights
Hydrogen gas (H2) is considered the promising clean fuel [1], due to its potentially higher efficiency of conversion to usable power, low or none pollutant formation and high energy density [2]
The inoculated a physiological solution was vaccinated under anaerobic conditions on the solid reinforced clostridial medium (RCM), which was equipped on the Petri dishes in order to obtain pure and individually colonies of anaerobic bacteria
Five isolates were used to study the production of metabolic gases
Summary
Hydrogen gas (H2) is considered the promising clean fuel [1], due to its potentially higher efficiency of conversion to usable power, low or none pollutant formation and high energy density [2]. Low-cost and sufficient supply of H2 could soon become in urgent demand [3]. Hydrogen as fuel can be produced by biological or nonbiological processes. It can be produced using fermentative bacteria, photosynthetic bacteria or algae. Biological H2 production using fermentative, photosynthetic bacteria, or algae is an environmentally friend and energy saving process [4] [5]. It is a feasible alternative for global H2 supply in the future [6]
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