厌氧发酵过程pH对微生物多样性和产物分布的影响

采用PCR-DGGE技术,研究了不同pH条件下蔬菜类有机垃圾厌氧发酵过程中的微生物多样性,探讨了微生物群落结构与发酵产物分布的关系.Shannon指数分析表明,pH=7和pH=8时的微生物多样性较高,随时间变化规律相似,而pH=5时的微生物多样性较低.UPGMA聚类分析和PCA分析结果也表明,pH=7和pH=8时的微生物群落结构相似,pH=5与之显著不同.在不同pH条件下的优势菌属都是乳酸细菌和梭菌。微生物多样性的变化与发酵产物分布具有一定相关性,pH通过影响微生物群落结构的变化最终影响发酵产物的分布.图4表2参27

Effect of pH on Microbial Diversity and Product Distribution During Anaerobic Fermentation of Vegetable Waste

pH is the prominent parameter influencing the product distribution of anaerobic fermentation where bacteria play a key role.To estimate the effect of pH(5,7 and 8)on bacterial diversity and correlation between product distribution and bacterial community structure during the fermentation of vegetable waste,polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)was applied.Three statistical methods were used to analyze the DGGE profiles.Shannon diversity index revealed that the bacterial diversity at pH=5 was a bit lower than that at pH=7 or pH=8.Dendrograms calculated with unweighted pair group method with arithmetic mean(UPGMA)indicated a close similarity of bacterial communities between pH=7 and pH=8,while the bacterial community at pH=5 differed.Analysis based on primary component analysis(PCA)presented a consistent conclusion but more detailed with information about bacterial evolution.According to the results of sequencing,lactic acid bacteria and Clostridium sp.were predominant at all pH values.Bacterial community during fermentation was materially influenced by pH which finally caused the diverse product distributions of fermentation.Fig 4,Tab 2,Ref 27