Open AccessCompetition between homoacetogenic bacteria and methanogenic archaea for hydrogen at low temperature
Author(s) -
Kotsyurbenko Oleg R.,
Glagolev Michail V.,
Nozhevnikova Alla N.,
Conrad Ralf
Publication year - 2001
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2001.tb00893.x
Subject(s) - biology , methanogenesis , archaea , strain (injury) , euryarchaeota , gibbs free energy , bacteria , anoxic waters , atmospheric temperature range , microorganism , thermophile , hydrogen , microbiology and biotechnology , food science , ecology , thermodynamics , chemistry , physics , genetics , organic chemistry , anatomy
Methanogens and homoacetogens compete for available H 2 in anoxic environments. The competitiveness of these microorganisms was studied by measuring H 2 consumption kinetics ( V max , K m , threshold) in different psychroactive strains as function of temperature. Methanogenic strains MSB and MSP and homoacetogenic Acetobacterium bakii, A. paludosum, A. fimetarium, A. tundrae , which were isolated from different low‐temperature environments, were all able to grow and consume H 2 in a temperature range of 4–30°C. The H 2 thresholds steadily decreased with decreasing temperature in cultures of A. bakii , A. tundrae and strain MSB. In A. paludosum, A. fimetarium and especially in strain MSP, however, H 2 thresholds again increased below 10–15°C. With exception of strain MSP at ≤10°C, H 2 thresholds were generally lower in the methanogens (<2 Pa H 2 ) than homoacetogens (<200 Pa H 2 ). The measured thresholds decreased in parallel to those predicted from thermodynamic theory, and thus allowed the calculation of a critical Gibbs’ free energy required for H 2 consumption, i.e. approximately −5 to −8 kJ mol −1 , being similar for methanogens and homoacetogens. V max increased with temperature. The increase was more pronounced in the methanogenic strains than in A. bakii , but the values of the latter were generally higher. K m also increased with temperature and was higher in A. bakii (about 190–520 Pa H 2 ) than in the methanogens (about 50–190 Pa H 2 ). The values of H 2 threshold, V max and K m , were used to compare the relative competitiveness of the different microorganisms over the entire temperature range using a kinetic model. A. bakii revealed a generally strong competitiveness for H 2 at high H 2 concentrations because of higher V max . It also outcompeted the methanogenic strain MSP at low H 2 and low temperature. However, the capacity of the methanogens to compete with A. bakii for H 2 increased with decreasing H 2 concentration because of more favorable K m and threshold. In the methanogenic strain MSB, the H 2 thresholds were generally lower than those of the homoacetogens irrespective of the temperature, and thus it outcompeted A. bakii . Methanogenic strain MSP, on the other hand, was outcompeted by A. bakii at low temperature because of insufficient psychrotolerance.