Isolation and identification of thermophilic bacteria for efficient dead-pig composting

Abstract:

Abstract:［Objective］To isolate thermophilic bacteria to degrade organic substances of dead-pig.［Methods］Primary screening was done by using diluted plate count and selective medium，and then enzyme activity was measured for secondary screening． Two thermophilic bacterial strains N-3 and Y-3 were isolated，and could degrade protein and lipids．To test their effect，the isolates were mixed (V:V = 1:1，the number of bacteria was 108 CFU /mL) and inoculated in dead-pigs and sawdust composting with different doses (0%，0.3%，0.6% and 0.9% of the wet weight of fermentation materials).［Results］Strain N-3 was identified as Bacillus aestuarii and Y-3 as Geobacillus thermodenitrificans，based on their 16S rDNA gene sequences． The composting temperature of the 0.3%，0.6% and 0.9% inoculation group could reach 60 ℃ and maintain at the high temperature for about 10 d，which is higher than control (P＜0.01)．At the end of composting，the dead-pig degradation rate of the (0%，0. 3%，0.6% and 0.9% inoculation groups were 71.2%，75.7%，96.7% and 97.1%，respectively．The groups of 0. 6% and 0.9% were significantly higher than the control (P＜0.01)．［Conclusion］ Sufficient amount inoculation of thermophilic bacteria (＞0.6%) could effectively increase composting temperature，maintain thermophilic stage for longer time，and accelerate degradation of dead-pig by composting．