Effects Of Physico-chemical Parameters On The Actinomycetal Communities During Agricultural Waste Composting

Composting technology has already been widely used in agricultural waste treatment, and to some extent it has made the agricultural solid waste reduction, harmless and recycling. However, the poor efficiency of lignocelluloses degradation is still a problem demanding prompt solution. Actinomycetes plays a non-ignorable role in agricultural waste composting. So it has important practical significance to research the relationship between actinomycetal community and physico-chemical parameters during agricultural waste composting. In this research, the total DNA which was abstracted from composting samples was amplified with PCR using the F243/R1378primers to obtain the actinomycetal16S rDNA genes. The products from primer pair F243/R1378were then used as a template for a second PCR with primer pair F984GC/R1378, which allowed us to obtain a fragment which is suitable for DGGE. The amplified products were separated by DGGE to obtain the information of actinomycetal community. Actinomycetal DGGE pattern was dealed with QuantityOne2.0to obtain the data of actinomycetal community. DGGE pattern showed that actinomycetal species increased quickly at the beginning of composting, then remained stable and appeared dominant actinomycetes population in the middle of composting, and increased again and disappeared dominant actinomycetes population in the late of composting.Real-time qPCR was used to monitor the quantity of actinomycetes with the primer pair F243/R1378. The result of Real-time qPCR showed that the qunantity of actinomycetes followed a rule which was "increase-decrease-increase" during agricultural waste composting.The purpose of the RDA was to determine which combination of parameters explained the most, if any, of the actinomycetal species composition differences of our compost samples.Then redundancy analysis (RDA) was used to explore the relationship between actinomycetal species and composting physico-chemical parameters:moisture content, water soluable carbon (WSC), C/N ratio, ambient temperature, pile temperature, pH, NH4+-N and NO3--N by using Canoco4.5. The relationship between sampling points and the8physico-chemical parameters was clearly revealed on the RDA biplot. The result of RDA indicated that parameters that affect actinomycetal dynamic successions were listed as the following order:moisture>C/N>WSC>pH> NH4+-N> pile temperature>NO3--N> ambient temperature. Among the8physico-chemical parameters, moisture and WSC (p<0.01), pH (P<0.05)significantly affected the variation of actinomycetal species during agricultural waste composting. Regression analysis was used to study the correlation between physico-chemical parameters and actinomycetal16S rDNA gene abundance by SPSS (version11.5). Regression line and scattered dots were drawn on a picture. The output of regression analysis indicated that moisture content showed a negative linear relationship with the actinomycetal16S rDNA gene abundance (R2=0.450,P<0.01). The effective control of these parameters will be significant for giving full play to the role of the actinomycetes in agricultural waste composting.