The biodegradation of poly(3‐hydroxy‐butyrate‐co‐3‐hydroxyvalerate) (PHB/V) and PHB/V‐degrading microorganisms in soil

To assess the polyhydroxyalkanoate (PHA)‐biodegrading capacity of soil, numbers of aerobic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHB/V)‐degrading microorganisms (degraders) were estimated by the film‐MPN method. The numbers of PHB/V degraders were estimated to be 4.3 × 105 per gram of dry garden soil, 5.06 × 105 per gram of dry paddy‐field soil, and 3.87 × 105 per gram of dry river‐bank soil. The degradations of PHB/V in suspensions of the three kinds of soil were investigated. It was found that the PHB/V‐biodegrading capacity of the soil increased as the number of PHB/V degraders in the soil increased. The relationship between weight loss of PHB/V and proliferation rate of PHB/V degraders in garden soil suspension was investigated. The effect of glucose on the biodegradation of PHB/V in garden soil was also studied. The weight loss after one week in garden soil suspension supplemented with 20 mM of glucose (GSS‐20G) was 2.60%, which was lower than that in garden soil suspension (GSS) (7.14%). After five weeks, the weight loss had increased to 24.97% in GSS‐20G but only to 18.26% in GSS. The results showed that glucose played important roles in inhibition and acceleration of different biodegrading phases and finally accelerated the PHB/V biodegradation in soil suspension.