Effects of various pretreatment methods on mixed microflora to enhance biohydrogen production from corn stover hydrolysate
2011
Zhang, Kun | Ren, Nanqi | Guo, Changhong | Wang, Aijie | Cao, Guangli
Five individual pretreatment methods, including three widely-used protocols (heat, acid and base) and two novel attempts (ultrasonic and ultraviolet), were conducted in batch tests to compare their effects on mixed microflora to enhance hydrogen (H₂) production from corn stover hydrolysate. Experimental results indicated that heat and base pretreatments significantly increased H₂ yield with the values of 5.03 and 4.45 mmol H₂/g sugar utilized, respectively, followed by acid pretreatment of 3.21 mmol H₂/g sugar utilized. However, compared with the control (2.70 mmol H₂/g sugar utilized), ultrasonic and ultraviolet pretreatments caused indistinctive effects on H₂ production with the values of 2.92 and 2.87 mmol H₂/g sugar utilized, respectively. The changes of soluble metabolites composition caused by pretreatment were in accordance with H₂-producing behavior. Concretely, more acetate accumulation and less ethanol production were found in pretreated processes, meaning that more reduced nicotinamide adenine dinucleotide (NADH) might be saved and flowed into H₂-producing pathways. PCR-DGGE analysis indicated that the pretreatment led to the enrichment of some species, which appeared in large amounts and even dominated the microbial community. Most of the dominated species were affiliated to Enterobacter spp. and Escherichia spp. As another efficient H₂ producer, Clostridium bifermentan was only found in a large quantity after heat pretreatment. This strain might be mainly responsible for better performance of H₂ production in this case.
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