Two subsamples of 10 g of fresh soil per sample were suspended in 90 ml of sterile deionized water.These bacterial suspensions were mixed in an orbital shaker at 300 rpm for 15 min, sonicated in anultrasonic cleanerfor 5 min and again mixed in the orbital shaker for 2 min. After 1 min ofsedimentation.further 10-fold.isolation of copiotrophic and oligotrophic bacteria,respectively.After incubation for 60 h(copiotrophs) or 4 weeks (oligotrophs) at 25 8C in the dark, bacterial colonies were counted and colonyforming units (CFUs) were calculated per g dry soil.