Mannitol as a Growth Substrate for Facultative Methylotroph Methylobrevis pamukkalensis PK2.

Biochemistry of carbon assimilation in aerobic methylotrophs growing on reduced C1 compounds has been intensively studied due to the vital role of these microorganisms in nature. The biochemical pathways of carbon assimilation in methylotrophs growing on multi-carbon substrates are insufficiently explored. Here we elucidated the metabolic route of mannitol assimilation in the alphaproteobacterial facultative methylotroph Methylobrevis pamukkalensis PK2.

Interchangeability of class I and II fumarases in an obligate methanotroph Methylotuvimicrobium alcaliphilum 20Z.

The methanotrophic bacterium Methylotuvimicrobium alcaliphilum 20Z is an industrially promising candidate for bioconversion of methane into value-added chemicals. Here, we have study the metabolic consequences of the breaking in the tricarboxylic acid (TCA) cycle by fumarase knockout. Two fumarases belonging to non-homologous class I and II fumarases were obtained from the bacterium by heterologous expression in Escherichia coli.

Enzymes of an alternative pathway of glucose metabolism in obligate methanotrophs.

Aerobic methanotrophic bacteria utilize methane as a growth substrate but are unable to grow on any sugars. In this study we have shown that two obligate methanotrophs, Methylotuvimicrobium alcaliphilum 20Z and Methylobacter luteus IMV-B-3098, possess functional glucose dehydrogenase (GDH) and gluconate kinase (GntK). The recombinant GDHs from both methanotrophs were homotetrameric and strongly specific for glucose preferring NAD over NADP.

Alteration of cofactor specificity of the acrylyl-CoA reductase from Escherichia coli.

Objectives: Alteration of the cofactor specificity of acrylyl-CoA reductase (AcuI) catalyzing the NAD(P)H-dependent reduction of acrylyl-CoA to propionyl-CoA is often desirable for designing of artificial metabolic pathways of various appointments.

Results: Several variants of AcuIs from Escherichia coli K-12 with multiple amino acid substitutions to alter the cofactor preference were obtained by site directed mutagenesis and the modified enzymes as His-tagged proteins were characterized. The simultaneous substitutions of arginine-180, arginine-198 and serine-178 residues by alanine in the enzyme pocket sequence as well as other amino acid changes decreased both NADPH- and NADH-dependent activities in comparison to the wild-type enzyme.

Ectoine degradation pathway in halotolerant methylotrophs.

Background: Microorganisms living in saline environments are forced to regulate turgor via the synthesis of organic osmoprotective compounds. Microbial adaptation to fluctuations in external salinity includes degradation of compatible solutes. Here we have examined the biochemical pathway of degradation of the cyclic imino acid ectoine, the major osmoprotector in halotolerant methane-utilizing bacteria.