Open AccessNew insights into the kinetics of bacterial growth and decay in pig manure–wheat straw aerobic composting based on an optimized PMA – qPCR method
Author(s) -
Ge Jinyi,
Huang Guangqun,
Sun Xiaoxi,
Yin Hongjie,
Han Lujia
Publication year - 2019
Publication title -
microbial biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.287
H-Index - 74
ISSN - 1751-7915
DOI - 10.1111/1751-7915.13380
Subject(s) - bacteria , manure , straw , food science , bacterial growth , chemistry , propidium monoazide , aerobic bacteria , mesophile , microorganism , compost , biology , real time polymerase chain reaction , agronomy , biochemistry , genetics , gene
Summary Aerobic composting is a bacteria‐driven process to degrade and recycle wastes. This study quantified the kinetics of bacterial growth and decay during pig manure–wheat straw composting, which may provide insights into microbial reaction mechanisms and composting operations. First, a propidium monoazide–quantitative polymerase chain reaction ( PMA – qPCR ) method was developed to quantify the viable bacteria concentration of composting samples. The optimal PMA concentration and light exposure time were 100 μM and 8 min respectively. Subsequently, the concentrations of total and decayed bacteria were quantified. Viable and decayed bacteria coexisted during the entire composting period (experiments A and B), and the proportion of viable bacteria finally fell to only 35.1%. At the beginning, bacteria grew logarithmically and decayed rapidly. Later, the bacterial growth in experiment A remained stable, while that of experiment B was stable at first and then decomposed. The duration of the stable stage was positively related to the soluble sugar content of composting materials. The logarithmic growth and rapid decay of bacteria followed Monod equations with a specific growth (0.0317 ± 0.0033 h −1 ) and decay rate (0.0019 ± 0.0000 h −1 ). The findings better identified the bacterial growth stages and might enable better prediction of composting temperatures and the degree of maturation.