Isolation and Characterization of Methanohalophilus portucalensis sp. nov. and DNA Reassociation Study of the Genus Methanohalophilus

Abstract

Six strains of coccoid, halophilic methanogens were isolated from various salinaria and natural hypersaline environments. These isolates (strains FDF-lT [T = type strain], FDF-2, SF-2, Ret-1, SD-1, and Cas-1) grew on media containing methanol and mono-, di-, and trimethylamines as catabolic substrates, but not on media containing dimethyl sulfide, methane thiol, H , , formate, or acetate; when cells were provided with H, in addition to methanol or trimethylamine, they grew on the medium containing a methyl substrate but did not catabolize H,. All of the strains were capable of growth in mineral medium to which trimethylamine was added as a catabolic substrate, although some strains were greatly stimulated by biotin or p-aminobenzoate. DNA reassociation and denaturing electrophoresis of whole-cell proteins indicated that strains FDF-lT, FDF-2, SF-2, and Ret-1, together with previously described strains SF-1, 2-7302, 2-7401, 2-7404, and 2-7405, belong to a new taxon named Methunohalophilzuportucalensis sp. nov; FDF-1 (= OCM 59) is the type strain. These strains grew fastest at temperatures near 40°C and, in medium containing 0.5 to 2.5 M NaCI, at pH values near 7. The two new strains excluded from the species on the basis of the results of phylogenetic tests, strains Cas-1 and SD-1, also differed from M. portucalensis in some minor physiological characteristics. Strain Cas-1 was less halophilic (fastest growth occurred in the presence of 0.5 to 1 M NaCI), and strain SD-1 was slightly alkaliphilic (fastest growth occurred at pH 7.8). The DNA reassociation study also showed that Methanohalophilus mahii SLPT exhibited 52% sequence similarity with Methanohalophilus halophilus 2-7982T, supporting the classification of these organisms as separate but closely related species.Halophilic methylotrophic methanogens are classified in two genera of slight halophiles and one genus each of moderate and extreme halophiles. Members of the genera Methanolobus and Methanococcoides are slight kalophiles of marine origin, growing fastest in the presence of less than 0.7 M NaCl (10,29,30). Members of the genus Methanohalophilus are moderately halophilic, growing fastest in the presence of 0.5 to 2.5 M NaCl (23), and members of the genus Methanohalobium are extremely halophilic, growing fastest in the presence of NaCl concentrations greater than 2 M (36). No genus other than these four contains halophilic met hylotrophic met hanogens; although several halophiles were reported in the closely related genus Methanosarcina (2, 28), other studies indicated that these species are halotolerant rather than halophilic (12, 13). The genus Halomethanococcus has also been proposed (33), but we do not include it in our taxonomy because we have been unable to obtain the type strain of the only species described in this genus (Halomethanococcus doii) and because the name Halomethanococcus may be a subjective synonym of Methanohalophilus.In addition to being unified by their halophily, which is recognized as an important taxonomic characteristic (4), ...

Regulatory Factors Associated with Synthesis of the Osmolyte Glycine Betaine in the Halophilic Methanoarchaeon Methanohalophilus portucalensis

“…The bacterial strain used in this study was M. portucalensis FDF1 (ϭ OCM59). This strain was isolated from the solar saltern of Figueria da Foz, Portugal, by Mathrani et al and was provided by R. Mah (4). The cells were routinely cultured in defined medium that contained 120 g of NaCl/liter and 20 mM trimethylamine or 100 mM methanol as the sole carbon and energy source (22).…”

Alkaliphiles: Some Applications of Their Products for Biotechnology

“…Boone et al (16) had originally isolated halophilic methanogens from various neutral salinas and natural hypersaline environments. These strains grew fastest at temperatures near 40°C and, in medium containing 0.5 to 2.5 M NaCl, at pH values near 7.…”

Anaerobic bacteria from hypersaline environments.

“…b +, weak uptake; + +, good uptake; + + +, very good uptake. (74) halophilus" (107) portucalensis (2) zhilinae (3,52) evestigatum ( a Numbers in parentheses after bacterial names are the references from which the data were gathered.…”