ISOLATION AND CHARACTERIZATION OF ISOPIMARIC ACID-DEGRADING BACTERIA FROM A SEQUENCING BATCH REACTOR

We isolated two aerobic, gram-negative bacteria which grew on the dite rpene resin acid isopimaric acid (IpA) as the sole carbon source and e lectron donor. The source of the isolates was a sequencing batch react or treating a high-strength process stream from a paper mill. The isol ates, IpA-1 and IpA-2, also grew on pimaric and dehydroabietic acids, and IpA-1 grew on abietic acid. Both strains used fatty acids, but nei ther strain used camphor, sitosterol, or betulin. Strain IpA-1 grew an aerobically with nitrate as an electron acceptor. Strains IpA-1 and Ip A-2 had growth yields of 0.19 and 0.23 g of protein per g of IpA, resp ectively. During growth, both strains transformed IpA carbon to approx imately equal amounts of biomass, carbon dioxide, and dissolved organi c carbon. In both strains, growth on IpA induced an enzymatic system w hich caused cell suspensions to transform all four of the above resin acids. Cell suspensions of IpA-1 and IpA-2 removed IpA at rates of 0.5 6 and 0.13 mu mol mg of protein(-1) h(-1), respectively. Cultures and cell suspensions of both strains failed to completely consume pimaric acid and yielded small amounts of an apparent metabolite from this aci d. Cultures and cell suspensions of both strains yielded large amounts of three apparent metabolites from dehydroabietic acid. Analysis of 1 6S rDNA sequences indicated that the isolates are distinct members of the genus Pseudomonas sensu stricto.