Methanohalophilus Mahii Gen. Nov. Sp. Nov. a Methylotrophic Halophilic Methanogent J
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INTERNATIONALJOURNAL OF SYSTEMATICBACTERIOLOGY, Jan. 1988, p. 122-123 Vol. 38, No. 1 00120-7713/88/010122-02$02.00/0 Copyright 0 1988, International Union of Microbiological Societies Methanohalophilus mahii gen. nov. sp. nov. a Methylotrophic Halophilic Methanogent J. ROBERT PATEREK$* AND PAUL H. SMITH Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 3261 1 A new genus of methanogenic bacteria (Methanohalophilus) comprising a single species, Methanohalophilus mahii sp. nov., is described, The microorganisms of this genus require sodium chloride concentrations in the moderately halophilic range of 1.0 to 2.5 M for optimal growth and methanogenesis. Methanol and methylamines are the substrates that are utilized for growth. M. mahii is a methanogenic coccoid microor- ganism isolated from the sediments of the Great Salt Lake. The optimum temperature and salinity for growth and methanogenesis were 37°C and 2.0 M NaCl, respectively. The description is based on a single strain, strain SLP (= ATCC 35705), which is thus the type strain. A methanogenic microorganism was isolated from the (iii) Other microorganisms that have the same restricted sediments of Great Salt Lake in Utah. This habitat is the physiology and NaCl requirements have been isolated from largest terminal lake in the United States, with total dis- hypersaline ecosystems (4,8; I. M. Mathrani, D. R. Boone, R. solved solids reaching a concentration of 332,480 mg/liter A. Mah, G. E. Fox, and P. L. Lau., submitted for publication). (7). In this paper we describe this organism; the description One of these isolates, strain WeN5, has beep proposed as a is based on the complete isolation and characterization member of Methanohalophilus, and the 16s ribosomal ribonu- results previously reported by Paterek and Smith (5). This cleic acid sequence of this organism supports the separation of organism, with the proposed but not validly published bino- this strain from all other methanogens and extreme halophiles men “Halomethanococcus mahii” (type strain SLP) was whose 16s ribonucleic acid or oligonucleotide catalogs have suggested as representing a novel genus. We propose that been determined (Mathrani et al., submitted for publication). type strain SLP be renamed Methanohalophilus mahii gen. This continuity of similar but unique microorganisms isolated nov., sp. nov. and be placed in the order Methanomicro- from similar environments worldwide suggests that formula- biales as described by Balch et al. (1) and Mah and Smith (3). tion of a new genus is required. We consider Methanohalophilus mahii to be a unique Description of Methanohalophilus gen nov. Methanohalo- organism and not a marine methanogen which has adapted to philus (Me. tha. no. ha. lo. phi’lus. M. L. n. methanum a hypersaline environment. This organism represents a novel methane; Gr. n. halo salt; Gr. no. philos lover; M. L. n. genus, as shown by the data described below. Methanohalophilus methane-producing salt lover). Mem- (i) The microorganisms in this proposed genus have a bers of this genus are nonsporeforming, nonmotile, irregular physiology restricted to the utilization of methanol and cocci which stain gram negative and occur singly or in small methylamines, which precludes their inclusion in the genera clumps. Cells lyse in the presence of 0.001% Triton X-100 or in the orders Methanobacteriales and Methanococcales, as 0.05% sodium dodecyl sulfate and in solutions with NaCl the previously described organisms in these orders can concentrations less than 0.3 M. Surface colonies are cream metabolize hydrogen for growth and methanogenesis (2). to pale yellow and circular and often appear foamy due to This suggests that these microorganisms should be assigned trapped gases. The colonies fluoresce yellowish green under to the order Methanomicrobiales and the family Methano- 420-nm excitation. Growth and methanogenesis require so- sarcinaceae (2, 3). Two genera, Methanococcoides and dium, magnesium, iron, and potassium, with the maximum A4ethanolobus, have been reported to have the same re- response occurring at a sodium concentration between 0.5 stricted physiology. Methanococcoides methylutens and our and 2.5 M. Methanol, methylamine, dimethylamine, and isolate are markedly different in their optimum levels of trimethylamine support growth and methane production. No salinity for growth. Our isolate is halophilic (optimum NaCl growth occurs with hydrogen-carbon dioxide, acetate, for- concentration, 2.0 M), and Methanococcoides methylutens mate, methionine, choline, or betaine. Organisms are found is only weakly halophilic (NaCl optimum, 0.4 M) (6). Our in anaerobic sediments with salinity levels at or above isolate was screened for antigenic reaction with Methano- seawater concentration. lobus tindarius. No reaction occurred between our microor- Description of Methanohalophilus mahii sp. nov. Methano- ganism and the probe prepared with Methanolobus tindarius halophilus mahii (mah’i. i. N. L. n. mahii of Mah, in honor (E. Conway de Macario, personal communication). of R. A. Mah for his noteworthy research history in the areas (ii) The antigenic fingerprint of our organism showed no of anaerobic microbiology and methanogenic bacteria). Mor- reaction with S probes produced from the antisera of 24 phology and colony characteristics are the same as those methanogenic strains. A very weak reaction (less than level described above for the genus. Sodium chloride optimum, 1) occurred against the probe for methanococcus mazei MC6 2.0 M. Temperature optimum, 35”C, no growth at tempera- (Conway de Macario, personal communication). tures above 45°C. pH optimum, approximately 7.5. Source, anaerobic sediment from Great Salt Lake, Utah. Physiology, * Corresponding author. fastidious anaerobe. Trimethylamine, dimethylamine, meth- t Florida Agricultural Experiment Station Journal Series No. ylamine, and methanol serve as substrates for growth and 8551. methanogenesis; hydrogen-carbon dioxide, formate, and ac- $ Present address: Oxford Environmental Corp., Tulane Univer- etate do not serve as substrates. The guanine-plus-cytosine sity Riverside Research Facility, Belle Chasse, LA 70037. content of the deoxyribonucleic acid is 48.5 mol%, as 122 VOL. 38, 1988 NOTES 123 determined by buoyant density. No definite antigenic rela- group. Microbiol. Rev. 43:26&296. tionship occurs between type strain SLP and members of the 2. Jones, W. J., D. P. Nagle, Jr., and W. B. Whitman. 1987. families Methanobacteriaceae, Methanomicrobiaceae, and Methanogens and the diversity of archaebacteria. Microbiol. Methanosarcinaceae as revealed by indirect immunofluores- Rev. 51:135-177. 3. Mah, R. A., and M. R. Smith. 1981. The methanogenic bacteria, cence serotyping (Conway de Macario, personal communi- p. 948-977. In M. P. Stan-, H. Stolp, H. G. Truper, A. Balows, cation). The type strain is strain SLP (Salt Lake Paterek). and H. G. Schlegel (ed.), The prokaryotes. A handbook on This strain has been deposited in the American Type Culture habitats, isolation and identification of bacteria. Springer-Verlag, Collection as strain ATCC 35705. Berlin. 4. Mathrani, I. M., and D. R. Boone. 1985. Isolation and character- ization of a moderately halophilic methanogen from a solar We thank J. P. Poe, Department of Classical Languages, Tulane saltern. Appl. Environ. Microbiol. 50:14&143. University, New Orleans, La., for aid with the etymology of the 5. Paterek, J. R., and P. H. Smith. 1985. Isolation and characteri- binomen. We also thank E. Conway de Macario for immunological zation of a halophilic rnethanogen from Great Salt Lake. Appl. typing of the isolate. Environ. Microbiol. 50:877-881. This work was part of a cooperative program (Methane from 6. Sowers, K. R., and J. G. Ferry. 1983. Isolation and characteriza- Biomass and Wastes) sponsored by the Institute of Food and tion of a methylotrophic marine methanogen, Methanococcoides Agricultural Sciences of the University of Florida and the Gas methylutens gen. nov., sp. nov. Appl. Environ. Microbiol. Research Institute. 456844590. 7. Stube, J. C., F. J. Post, and D. B. Procella. 1976. Nitrogen cycling in microcosms and application to the biology of the north arm of LITERATURE CITED the Great Salt Lake. Publication no. PRRJSBA-016-1. Utah Water Research Laboratory, Utah State University, Logan. 1. Balch, W. E., G. E. Fox, L. J. Magrum, C. R. Woese, and R. S. 8. Zhilina, T. N. 1983. New obligately halophilic methane-pro- Wolfe. 1979. Methanogenesis: reevaluation of a unique biological ducing bacterium. Mikrobiologiya 52:290-297. .