[Biosynthesis of secondary metabolites in methanotrophs: biochemical and genetic aspects (review)].

The review summarizes the data on the metabolic potential of methanotrophs as producers of biopolymers, alternative biofuel, bioprotectants, and other secondary metabolites. The work provides the examples of modern 'omic' technologies used for genetic engineering of efficient methanotrophic producers.

[Properties of modified amperometric biosensors based on methanol dehydrogenase and Methylobacterium nodulans cells].

The properties of amperometric biosensors based on methanol dehydrogenase (MDH), Methylobacterium nodulans cells, and the ferrocene-modified carbon paste electrode were investigated. It was shown that the addition ofhydroxyapatite (HA) to a carbon paste increased the sensitivity and operating stability of MDH biosensors. The linear range of the electrode was 0.0135-0.5 and 0.032-1.5 mM for methanol and formaldehyde, respectively. The detection limit of methanol and formaldehyde was 4.5 and 11.0 microM, respectively. The loss of activity of the electrode within 10 days of storage in the presence of 2.0 mM KCN did not exceed 12%. Cyanide (10 mM) completely inhibited the sensor responses to formaldehyde (1.0 mM), which allowed for the selective determination of methanol in the presence of formaldehyde. The biosensor based on cells exhibited lower stability and sensitivity toward methanol and formaldehyde; the sensitivity coefficients were 980 and 21 nA/mM, respectively.

[Purification and characteristics of methanol dehydrogenase of Methylobacterium nodulans rhizosphere phytosymbionts].

Methanol dehydrogenase (MDG) of the facultative methylotrophic phytosymbiont Methylobacterium nodulans has been purified for the first time to an electrophoretically homogeneous state and characterized. The native protein with a molecular mass of 70 kDa consists of large (60 kDa) and small (6 kDa) subunits. The purified protein displayed a specter identical to that of pyrochinolinchinon (PCC)-containing MDGs (pI 8.7, pH optimum in the range 9-10). The enzyme was inactive in the absence of ammonium or methylamine and exhibited a wide substrate specificity with regard to C1-C2 alcohols with the highest affinity to methanol (K(M) = 70 mM), but it did not oxidize benzyl and secondary alcohols. The apparent values of K(M) to primary alcohols increased with the length of the carbonic chain. The enzyme was characterized by a high stability level even in the absence of a substrate. An immobilized enzyme was used for amperometric methanol detection.

[Biosynthesis of the bioprotectant ectoin by aerobic methylotrophic bacteria from methanol].

It is shown that neutrophilic methylobacteria Methylophaga thalassica and M. marina have higher rates of growth and ectoin accumulation compared to the haloalkaliphilic species M. alcalica and M. natronia and methanotrophs Methylomicrobium alcaliphilum and M. kenyense. The conditions of M. thalassica cultivation in methanol-containing medium were optimized. The yield of this process reached 60 g/l of absolutely dry biomass containing 15-19% (9-11 g/l) ectoine. The scheme of ectoin isolation from the biomass by extraction and subsequent purification, which allowed obtaining preparations of different degree of purity, was developed.