Analysis Of The Mechanism Of Syntrophic Acetogenic Bacteria In Anaerobic Fermentation

Wastewater treatment is an essential process to help maintain the integrity and health of the environment and people.Although wastewater treatment is essential ,it is an energy consuming and thus costly process.Under anaerobic conditions,the organic,biologically degradable material in the waste can be used as an energy and food source for microorganism to produce products of value,mainly VFAs. Producing high value biochemicals,including VFAs, by further fermentation is a new way by which wastewater is used as resources.Syntrophic acetogenic bacteria, an important functional one in anaerobic habitats, were detected and counted by fluorescence in situ hybridization technology, using 16S rRNA-based oligonucleotide probes. For enumeration and quantity of the targeted bacteria, an attempt was made for optimizing hybridization conditions, including a fixation time of 19h, a dehydrated time of 5min, and a formamide concentration of 55% in hybridized solution. The abundance of syntrophic acetogenic bacteria of different environmental samples were quantified by FISH, among which , anaerobic reactor treating high-concentration organic wastewater and the digestive tract of some animals were the main habitats of syntrophic acetogenic bacteria, such as, the contents of the bacteria of UASB and cattle manure were as follows, respectively: 1.70×109 cells/mL sample, 6.50×108 cells/mL sample, meanwhile, the sediments of rivers and lakes existed less of the bacteria ,for example, the contents of them were just about 1.20×108 cells/mL sample in Taihu lake.2-Bromoethanesulphonate and chloroform are effective chemical additives for inhibiting methane bacteria in anaeroboic fermentation.For this reason, the two substance was added during fermentation to hunt for the change of metabolism channel of production,at the same time,quantitive FISH was used to exam the altering of syntrophic acetogenic bacteria.It is proved that more waste consistency,more BES. BES inhanced the produce of VFAs,meanwhile, aggrandized the kinds of VFAs and transferred the metabolism channel of production.In comparison with BES, chloroform is more powerful. Chloroform accelerated the speed of acidification, simultaneously,curtailed fermentation period, including elevating production yield and varying diversity of VFAs. It was to a certain degree that BES and chloroform inhibited syntrophic acetogenic bacteria.Saturated fatty acid-β-oxidizing syntrophs and syntrophic propionate-oxidizing bacteria didn't interrelate with Propionate and Butyrate(p>0.05),at the same time, syntrophic acetogenic bacteria had no correlation with Acetate(p>0.05),either.The quantity of Syntrophic acetogenic bacteria didn't relate to production ,but microbe activity had influenced the VFAs.