Effects of Formic or Acetic Acid on the Storage Quality of Mixed Air-Dried Corn Stover and Cabbage Waste, and Microbial Community Analysis

Haiwei Ren1,2*small orcid_display_4pp, Cong Wang1
small orcid_display_4pp, Wenguang Fan1small orcid_display_4pp, Bingyun Zhang1small orcid_display_4pp, Zhizhong Li1small orcid_display_4pp and Dong Li3small orcid_display_4pp

1School of Life Science and Engineering, Lanzhou University of Technology, 287 Langongping Road, 730050 Lanzhou, PR China
2Key Laboratory of Complementary Energy System of Biomass and Solar Energy, Gansu Province, 287 Langongping Road, 730050 Lanzhou, PR China
3Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Science, No. 9, Section 4, Renmin South Road, 610041 Chengdu, PR China

Article history:
Received: July 30, 2017
Accepted: February 1, 2018

Key words:
air-dried corn stover, cabbage waste, mixed ensiling, formic and acetic acids, fermentation quality, microbial community diversity

A mixture of air-dried corn stover and cabbage waste was ensiled to preserve lignocellulosic biomass for use as biofuel. Furthermore, the effects of different fresh mass fractions (0.3 and 0.6 %) of formic or acetic acid on the mixed silage quality were evaluated to guarantee its quality. The application of formic or acetic acid prior to mixing the silage led to higher water-soluble carbohydrate fractions than the negative control, indicating that both acids contributed to preservation of water-soluble carbohydrates during storage for 170 days. The dry matter content was also increased after storage from 90 to 170 days. It was found that the content of neutral and acid detergent fibre, cellulose and holocellulose (the sum of cellulose and hemicellulose) in mixed silage treated with formic or acetic acid was significantly lower than that obtained in the negative control. The pH and the ratio of ammoniacal nitrogen to total nitrogen in mixed silage treated with acetic acid also significantly decreased. Furthermore, the addition of formic or acetic acid significantly weakened the fermentation intensity of lactic acid, depending on the ratio of lactic to acetic acid, as well as the ratio of lactic acid to total organic acids. The number of bacterial species and their relative abundance shifted during silage mixing, wherein microbial communities at phylum level mainly consisted of Proteobacteria and Firmicutes. The dominant bacteria were also observed to shift from Lactobacillus and Enterobacter in presilage biomass to Lactobacillus and Paralactobacillus. Specifically, Enterobacter disappeared after 130 days of storage. In conclusion, the addition of a low dose of acetic acid to fresh mass (0.3 %) could effectively improve the fermentation quality and is conducive to the preservation of the organic components.

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Paper was presented at the 7th International Forum on Industrial Bioprocessing - IFIBiop 2017, May 21-24, 2017, Wuxi, PR China