Polyhydroxyalkanoate synthesis from alcohols during the growth ofParacoccus denitrificans

Several alcohols were examined as substrates for the polyhydroxyalkanoate synthesis by Paracoccus denitrificans. The bacterium synthesized a homopolyester of poly(3-hydroxybutyrate) from ethanol. When n-pentanol was used as growth substrate, homopolyester poly(3-hydroxyvalerate) was synthesized, whereas copolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulated during bacterial growth on n-propanol. When alcohols were automatically fed as growth substrates, ethanol, n-propanol, and n-pentanol gave higher polyester content. Although poly(3-hydroxybutyrate) was synthesized from methanol or n-butanol, its content was very low. Under nitrogen-deficient conditions, polyester;content in cells increased, especially with ethanol, n-propanol, and n-pentanol. Using a mixture of two alcohols P. denitrificans could synthesize polyesters with varying relative ratios of 3-hydroxybutyrate to 3-hydroxyvalerate.