Aeromonas hydrophila (A. hydrophila) 4AK4 produced poly(3 hydroxybutyrate co 3 hydroxyhexanoate) (PHBHHx) with an almost constant 3 hydroxyhexanoate (3HHx) content of 10%15% from lauric acid and/or soybean oil. Both A. hydrophila 4AK4 and recombinant Escherichia coli (E. coli) JMU193 (pBH32) produced PHBHHx with controllable 3HHx content when fed lauric acid and another co substrate. With glucose or gluconate as the co substrate, the 3HHx content in the copolyester produced by A. hydrophila 4AK4 was reduced slightly from 12% to 9%. However, the 3HHx content in the copolyester produced by E. coli JMU193 (pBH32) was significantly reduced from 9% to 2% with fructose as the co substrate. These results show that regulation of 3HHx content in PHBHHx can be achieved using genetically engineered E. coli.
Microorganisms are commonly used to transform chemicals to chiral compounds. Pseudomonas cepacia 1813, Pseudomonas stutzeri 1317, Saccharomyces cerevisiae 1912, and 5 Escherichia coli strains were used to transform acetophenone to 2 phenylethanol. The results show that the E. coli strains have the poorest biotransformation ability. P. stutzeri 1317 provides the best transformation ability with a transformation rate of 30% achieved with either whole or broken P. stutzeri 1317 cells for a reaction pH of 8.2 and an initial acetophenone concentration of 2 g/L. An acetophenone concentration of 10 g/L strongly inhibits the biotransformation for a pH of 8.2. Crude alcohol dehydrogenase obtained from S. cerevisiae 1912 transforms acetophenone to 2 phenylethanol when nicotinamide adenine dinucleotide reduced (NADH) is added.
