Formaldehyde is a highly toxic chemical for all organisms, and it has recently been found as effluent from
industrial waste water to marine environment. The aims of this study were to investigate the effect of 10ppm
formaldehyde on the microbial communities isolated from five coastal sea water samples, collected from the Izu
Peninsula,Japan.Rapid decrease of formaldehyde concentration was only observed in a raw sample at the Kifu area
of Numazu city,but no decrease of this boiled sample.Six bacterial strains were isolated from the Kifu area by using
spread plate method. Effects of concentrations of 10ppm formaldehyde on each pure-cultured bacterial strain were
investigated in batch cultures.During the first ３ days,ca.95％ (v/v)of formaldehyde was rapidly decreased by three
bacterial strains (BR-41, ZB-51, and T1＋1). When the formaldehyde was used as sole carbon source in the M9
medium, these strains were not able to grow in the absence of glucose.However in the presence of glucose, 10ppm
formaldehyde did not inhibit the growth of the strain BR-41.And rapid decrease of formaldehyde concentration was
observed, indicating that the tolerance to 10ppm formaldehyde of strain BR-41 was occurred in M ９ medium.
Furthermore,in case of addition the trace metals to M ９ medium including 10ppm formaldehyde concentration,the
strain BR-41 was able to grow well and the 90％ (v/v) of formaldehyde was decreased of within 12h of the
incubation. The formaldehyde-resistant strain BR-41was classified to the family Alteromonadaceae by16S rRNA
gene sequence analysis.