Formate-assimilating Paracoccus sp. strain 12A accumulated polyester by using formic acid
as a sole carbon source without the intentional nitrogen-source limitation and restriction of
air supply. The polyester produced was identified as a copolyester of P(3HB-co-5mol%3HV)
by 1H and 13C NMR analysis. The molecular weight of copolyester was determined to be 6.4
x10^5 by GPC and its maximum content was 60% of dry cell weight. The strain could not
assimilate 2-hydroxyctanoic acid（2HO)．By the incubation of formic acid-grown cells in the
presence of 2HO for 24hr and 48hr at 30℃，however, 3HV content in P(3HB-co-5mol%3HV)
increased to 20% and 41%, respectively, under nitrogen-deficentconditions. The molecular
weight of these copolyester were 3.7x10^5 and 7.4x10^5,respectively. The copolyester contents
of respective cells were 18.4% and 21.3% of dry cell weight. Further, the presence of many
copolyester granules was observed in formic acid-grown cells by transmission electron
microscopy.
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