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Formaldehyde, Methylobacterium, Methylotroph, Enzyme
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.
Research papers (academic journals)
