生物产氢过程中厌氧污泥耐酸响应的生物化学机制

生物质厌氧发酵产氢过程中积累的大量酸性物质,会对厌氧微生物产生抑制作用,进而制约氢气的持续产生。作者采用不同浓度丁酸对污泥进行胁迫,结果表明:当丁酸胁迫质量浓度为6g/L时,污泥厌氧发酵过程中丁酸、乙酸以及氢气产量最高,分别达到1 071mmol/mol,462mmol/mol和3 690mL/mol,比对照组分别提高了110%,54%和65%;此外,产氢过程中谷氨酸脱羧酶(glutamic acid decarboxylase,GAD)、脱氢酶以及DNA总量活性最高达到11.6μmol/(g·TS·h),6 982.12μg TF/(g.TS.h),14.72ng/mL,相对于对照组分别提高了48%,50%,10.7%;同时,经过酸胁迫后,厌氧污泥胞外聚合物(extracellular polymeric sub-stances,EPS)含量有明显提高,与空白对照组相比松散型多糖和蛋白质以及紧密型多糖和蛋白质分别提高了147%,34.8%,35%,21.6%。因此,适宜浓度的丁酸胁迫可激发厌氧污泥的相关耐酸响应机制(Acid tolerance response,ATR),进而提高污泥的耐酸性能,并最终提高厌氧产氢效率。

Acid Tolerance Response of Anaerobic Sludge with Butyric Acid Stress during the Enhanced Biohydrogen Process

During the anaerobic digestion of biomass,large amounts of organic acids were produced.This results in an inhibitory effect on anaerobic microbiology,which in turn inhibits large-scale production of hydrogen.In this study,butyric acid was use as stress on the sludge,and it was found that the production rates of butyric acid,acetic acid and hydrogenwas reached at 400 mmol/mol,1100 mmol/mol,3690 mL/mol,respectively,which was higher 110%,54% and 65% than that of the corresponding values in the control group.Moreover,glutamate acid decarboxylase(GAD) activity,dehydrogenase activity and the content of DNA was increased to 11.6 μm/(g·TS·h),6982.12 μg TF/(g·TS·h) 14.72 ng/mL,with an increment of 48%,50%,10.7%,respectively.and the content of extracellular polymeric substances(EPS) have improved significantly,loose bound protein,loose bound polysaccharide,tight bound protein and tight bound polysaccharide content were 147%,34.8%,35%,21.6% higher than that of the control.The results demonstrate that the appropriate concentration of butyric acid stress on sludge can excite acid tolerance response(Acid tolerance response,ATR) and to improve acid tolerance of sludge,and improve the efficiency of anaerobic hydrogen production.