A new genus, Methyluphilus, and species of restricted facultative methanol-utilizing bacteria are described. These bacteria are aerobic gram-negative rods that occur singly and in pairs. In addition to methanol and glucose, a limited range of other carbon compounds including fructose and methylamines may be used as the sole carbon and energy source. The fatty acid composition is primarily of the nonhydroxylated straight-chain saturated and monounsaturated types. The major isoprenoid quinone components are ubiquinones with eight isoprene units. The major polar lipid components are phosphatidylglycerol and phosphatidylethanolamine. The deoxyribonucleic acid base composition is 50 to 53 mol% guanine plus cytosine. The name of the genus proposed for these bacteria is Methyluphilus gen. nov. The name of the type species is Methyluphilus methylutruphus sp. nov. The type strain is AS1 (= NCIB 10515).The ability to utilize methanol and some other singlecarbon compounds, but not methane, as the sole carbon and energy source is found among a variety of gram-positive and gram-negative bacteria (17). On the basis of the range of carbon compounds utilized, the bacteria can be divided into three groups: the obligate methanol utilizers that can use only single-carbon compounds such as methanol, methylamine, and formate; the restricted facultative methanol utilizers that also grow on a limited range of more complex organic compounds; and the less restricted facultative methanol utilizers that grow on a wider range of more complex carbon compounds as the sole carbon and energy source (4, 12). The majority of the last group and all members of the first two groups so far studied are gram-negative, aerobic, rod-shaped bacteria that superficially resemble pseudomonads. Until recently the taxonomy and nomenclature of these bacteria were unclear (17, 18). Consequently, they were not treated in Bergey's Manual of Systematic Bacteriology (18). Subsequent studies of the pink-pigmented, less restricted facultative methanol utilizers (7) have resulted in their classification in the genus Methylobacterium (1,8). The results of recent numerical taxonomic and chemical studies on a number of obligate, restricted, and less restricted methanol-utilizing, gram-negative bacteria and some pseudomonads confirmed the distinctness of the genus Methylobacterium and indicated that the obligate and restricted facultative forms represented two distinct taxa of generic status (11, 12; 0. Jenkins, Ph.D. thesis, University of Leicester, Leicester, United Kingdom, 1984). The obligate methanol utilizers studied could be equated with the genus Methylobacillus (Yordy and Weaver 1977). The restricted facultative methanol utilizers, many of which were cultures used for the production of single-cell protein, could not be placed in any validly named taxon (11, 12; Jenkins, Ph.D. thesis) but did include the organisms labeled "Methylophilus methylotrophus'' (NCIB 10515) and "Methylomonas Clara" (ATCC 31226). These results are in agreement with the two groups detected ...
Recombinant strains of Pseudomonas oleovorans, which harbour the poly(3-hydroxybutyrate)-biosynthetic genes of Alcaligenes eutrophus, accumulated poly(hydroxyalkanoates), composed of 3-hydroxybutyrate(3HB), 3-hydroxyhexanoate (3HHx) and 3-hydroxyoctanoate (3HO), up to 70% of the cell dry weight if the cells were cultivated with sodium octanoate as the carbon source. Physiological and chemical analysis revealed multiple evidence that this polymer is a blend of the homopolyester poly(3HB) and of the copolyester poly(3HHx-co-3HO) rather than a random or a block copolyester of 3HB, 3HHx and 3HO. The molar ratio between poly(3HHx-co-3HO) and poly(3HB) varied drastically during the process of fermentation. Whereas synthesis of poly(3HHx-co-3HO) started immediately after ammonium was exhausted in the medium, synthesis of poly(3HB) occurred only after a lag-phase. From freeze-dried cells poly(3HHx-co-3HO) was much more readily extracted with chloroform than was poly(3HB). The blend was fractionated into petrol-ether-insoluble poly(3HB) and petrol-ether-soluble poly(3HHx-co-3HO). The molecular weight values of these polyesters measured by gel permeation chromatography were 2.96 × 10 6 and 0.35 × 10 6 and were similar of those polymers accumulated by A. eutrophus or by wild-type P. oleovorans, respectively.
The glutamate dehydrogenase gene of Escherichia coli has been cloned into broad host-range plasmids and can complement glutamate synthase mutants of Methylophilus methylotrophus. Assimilation of ammonia via glutamate dehydrogenase is more energy-efficient than via glutamate synthase, thus the recombinant organism converts more growth substrate, methanol, into cellular carbon.
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