Effects of prechilling and sequential washing on enumeration of microorganisms from refuse

Techniques were evaluated for formation of a liquid inoculum from shredded municipal refuse, including chilling the refuse at 4 degrees C prior to blending and multiple washing and blending cycles. The average count of cellulolytic bacteria from six different detachment treatments was 5.1 x 10 cells per g (dry weight) of refuse with a range of 0.7 x 10 to 12.7 x 10 cells per g (dry weight). The liquid obtained from blending the refuse in phosphate buffer followed by hand squeezing was the selected detachment procedure. The inoculum formation procedure was validated by the addition of ruminal cellulolytic bacteria to refuse and recovery of the cellulolytic bacteria by most-probable-number enumerations. The ratio of measured to expected cell counts among tests in which different volumes of ruminal fluid were added to refuse ranged from 2.7 to 14.4. There was no evidence of anaerobic cellulolytic fungi in a refuse sample.