| Cellulose is a large amount of biomass existing widely in nature which are biodegradable,renewable organic polymer compounds.It is very important to utilize the cellulosic resources effectively from the industrial/agricultural organic wastes.In this study,high-temperature-resistant cellulose-degrading bacteria were isolated and screened from high-temperature compost samples.Secondly,the composition of the fermentation medium and the culture conditions for the newly isolated high-temperature-resistant cellulose-degrading bacteria were optimized.Thirdly,a compound microbial inoculant consisting of the newly isolated high-temperature-resistant cellulose-degrading bacteria and other frequently-used strains in fermentation composts was developed.Finally,the fermentation process of biochemical fulvic acid organic fertilizer using the compound microbial inoculant was preliminarily optimized.The chicken mushroom residues as the material samples for the isolation of high-temperature-resistant cellulose-degrading bacteria were obtained from the composting pile in Heshan New-established Biological Products Corporation.The samples were cultured in filter enrichment medium in 50°C,and then high-temperature-resistant cellulose-degrading bacteria was isolated and screened using the Congo red cellulose medium in 50°C.After purification,110 isolates having the capacity of cellulose degradation were selected for further screen,and finally a effective high-temperature-resistant cellulose-degrading strain,named XD-3,was obtained.The carboxymethy cellulase(CMCase)activity of the fermentation broth of strain XD-3 after 48 h fermentation in 50°C was 6.14 ± 0.37 U/m L.The combination of phylogenetic analysis based on 16 S r RNA gene sequence,morphological and biochemical characteristics supported the view that,strain XD-3 belonged to the genus Bacillus,and was most closely related to Bacillus amyloliquefaciens DSM 7T(sequence similarity,99.8 %).Thus strain XD-3 was preliminarily identified as a member of the species Bacillus amyloliquefaciens.The best composition of the fermentation medium and the culture conditions for the newly isolated high-temperature-resistant cellulose-degrading bacteria were obtained by using the combination of single factor and orthogonal experiments with the carboxymethy cellulase(CMCase)activity as an indicator: soluble starch 5g,corn steep liquor 4g,yeast powder 0.5g,(NH4)2SO4 2.0g,KH2PO4 4.0g,Ca Cl2 0.3g,Mg SO4·7H2O 0.3g,p H 6.5,water 1000 m L,40°C,48 h.The CMCase reached 48.27 ± 2.93 U/m L in fermentation broth by using the optimized fermentation medium at 40°C for 48 h,which was 5.8 times compared with the initial fermentation medium under the same conditions.Based on the result of aerobic high-temperature solid-state fermentation test,the best mixture ratio of a compound microbial inoculant consisiting of strains XD-3 and other frequently-used strains in fermentation composts,i.e.Bacillus subtilis HD-5,Saccharomyces cerevisiae HD-3 and Trichoderma viride HD-2,was 2:2:1:1.Then the aerobic-anaerobic-stage solid-state fermentation process of biochemical fulvic acid organic fertilizer using the compound microbial inoculant was preliminarily optimized based on the single-factor experiment.The optimized aerobic-stage fermentation parameters were: distiller's grains and mushroom residue(60% and 40%,respectively)used as the fermentation raw materials;initial moisture content,55%;initial p H 6;best inoculum dose of the compound microbial inoculant,5%;fermentation time,5 days.The optimized anaerobic-stage fermentation parameters were: 2% urea,1.5% potassium di-hydrogen phosphate and 15% sugarcane molasses as the best supplement materials;moisture content,remaining 55%;fermentation time,10 days.After the optimized aerobic-anaerobic-stage solid-state fermentation process,the humus of the achieved biochemical fulvic acid organic fertilizer was 32.31%(dry weight),humic acid,7.8%(dry weight),and biochemical fulvic acid,23.4%(dry weight). |
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