title: Formaldehyde-limited cultivation of a newly isolated methylotrophic bacterium, Methylobacterium sp. MF1: enzymatic analysis related to C1 metabolism.
abstract: Formaldehyde is a highly toxic compound to most living organisms. We have isolated a bacterial strain that is able to efficiently degrade formaldehyde and use it as a sole carbon source. The isolated strain was identified as Methylobacterium sp. MF1, which could grow on formaldehyde and methanol. Methylobacterium sp. MF1 was grown in batch culture using 1.2 g/l formaldehyde as a sole carbon source, which was all consumed within 200 h. In order to decompose formaldehyde more efficiently, formaldehyde-limited chemostat cultivation of Methylobacterium sp. MF1 was investigated. Formaldehyde was consumed at 1.7 g/l/d when the dilution rate was 0.012 h(-1). Under these conditions, the cell turbidity (OD610) reached 2.0. Furthermore, when the initial turbidity was adjusted to 3.0 using methanol-grown cells, continuous cultivation could be started at an initial dilution rate of 0.008 h(-1). Using these conditions, consumption of formaldehyde could be continued for at least 600 h. The enzyme activities of cells growing as a chemostat culture, using methanol or formaldehyde as a sole carbon source, were compared to that of C1 metabolism. No difference was detected in the enzyme activities for the oxidation and assimilation of C1 compounds between the two cell-free extracts. Furthermore, methanol dehydrogenase activity was detected at the same level when formaldehyde was used as a sole carbon source. These results suggest that the resistance to the toxic effects of formaldehyde exhibited by Methylobacterium sp. MF1 is related to factors other than C1 metabolism.
authors.affiliation: Department of Biochemistry, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan. rmitsui@dbc.ous.ac.jp
authors.forename: Ryoji
authors.initials: R
authors.lastname: Mitsui
authors.forename: Masahiro
authors.initials: M
authors.lastname: Omori
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kitazawa
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002244:Carbon / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D005557:Formaldehyde / Q000378:metabolism*; D020580:Methylobacterium / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D005557:Formaldehyde; D002244:Carbon; C020145:formaldehyde dehydrogenase (glutathione); D000445:Aldehyde Oxidoreductases