The kinetic mechanism of the unidirectional
H2-oxidizing hydrogenase from soybean nodule bacteroids has
been investigated with highly purified enzyme. Measurements
of the K, for H2 vary from 0.97 to 2.6 pM, and the K,,, for
methylene blue varies from 6 to 17 pM. With H2 and
methylene blue as substrates,...
Nitrobacter hamburgensis X14 is a facultative lithoautotroph that conserves energy from the
oxidation of nitrite (NO
2 ) and fixes carbon dioxide (CO2) as its sole source of carbon. The
availability of the N. hamburgensis X14 genome sequence initiated a re-examination of its
mixotrophic and organotrophic potential, as genes encoding...
Acetylene is a slow-binding inhibitor of the Ni- and Fe-containing dimeric hydrogenase isolated
from Azotobacter vinelandii. Acetylene was released from hydrogenase during the recovery from inhibition.
This indicates that no transformation of acetylene to another compound occurred as a result of the interaction
with hydrogenase. However, the release of C2H2...
Carbonyl sulfide (COS) has been investigated as a rapid-equilibrium inhibitor of CO oxidation
by the CO dehydrogenase purified from Rhodospirillum rubrum. The kinetic evidence suggests that the
inhibition by COS is largely competitive versus CO (Ki = 2.3 pM) and uncompetitive versus methylviologen
as electron acceptor (Ki = 15.8 pM)....
The placement of ‘Pseudomonas butanovora’ in the genus Thauera was proposed previously, based on 16S rRNA gene sequence analysis, upon further studies of taxonomical characteristics. In this study, physiological characteristics and DNA–DNA reassociation data are presented and the transfer of ‘P. butanovora’ to the genus Thauera is proposed. The original...
The effects of nitric oxide (NO) on the individual components of Azotobacter vinelandii
nitrogenase have been examined by kinetic and spectroscopic methods. Incubation of the Fe protein (Av2)
for 1 h with stoichiometries of 4- and 8-fold molar excesses of NO to Av2 dimer resulted in a complete
loss of...
Soluble butane monooxygenase (sBMO), a three-component di-iron monooxygenase complex
expressed by the C2–C9 alkane-utilizing bacterium Thauera butanivorans, was kinetically
characterized by measuring substrate specificities for C1–C5 alkanes and product inhibition
profiles. sBMO has high sequence homology with soluble methane monooxygenase (sMMO) and
shares a similar substrate range, including gaseous and...
Ammonia (NH₃)-oxidizing bacteria (AOB) and thaumarchaea (AOA) co-occupy most soils, yet no short-term growth-independent method exists to determine their relative contributions to nitrification in situ. Microbial monooxygenases differ in their vulnerability to inactivation by aliphatic n-alkynes, and we found that NH₃ oxidation by the marine thaumarchaeon Nitrosopumilus maritimus was unaffected...
Nitrosomonas sp. strain AL212 is an obligate chemolithotrophic ammonia-oxidizing bacterium (AOB) that was originally isolated in 1997 by Yuichi Suwa and colleagues. This organism belongs to Nitrosomonas cluster 6A, which is characterized by sensitivity to high ammonia concentrations, higher substrate affinity (lower K[subscript m]), and lower maximum growth rates than...
Agricultural land management, such as fertilization, liming, and tillage affects soil properties, including pH, organic matter content, nitrification rates, and the microbial community. Three different study sites were used to identify microorganisms that correlate with agricultural land use and to determine which factors regulate the relative abundance of the microbial...