| This research starts from the large-scale and efficient resource utilization of coffee grounds,and uses coffee grounds as the main material to carry out the optimization of the fermentation formula of three beneficial bacteria such as lactic acid bacteria,yeasts,and Trichoderma harzianum.We also studied the effects of the fermentation base material of coffee grounds on the growth and reproduction of earthworms through the earthworm digestion test,and analyzed the effect of the digestion process of earthworms on the cooking properties of the coffee grounds fermentation base.We also used the digested earthworm manure as a seedling substrate to preliminarily study its effects on the emergence rate of rice seeds,the biomass of rice seedlings and the formation of the rhizosphere bacterial community structure.The main research results are as follows.1.With coffee grounds as the main material,an orthogonal experiment was designed for the three factors of molasses concentration,wheat bran ratio and bacterial inoculum in the fermentation formula.The results showed:(1)The fermentation temperature of different formulas of coffee grounds reaches the peak time of 3?6 d,and the peak temperature is 32.1?46.3 ?.The addition of molasses and wheat bran significantly promoted the fermentation process of coffee grounds,and the peak temperature of the fermentation base material and the continuous fermentation level were significantly higher than the control.(2)The addition of molasses and wheat bran both promoted the growth and reproduction of microorganisms in the fermentation process of coffee grounds,with the highest increase of 3321.1%compared with the control treatment.The proportion of molasses added was the main factor affecting the growth and reproduction of microorganisms in the fermentation process of coffee grounds;The addition of molasses and wheat bran generally promoted the increase of the pH value of the base material during the fermentation process of coffee grounds,and the addition ratio of wheat bran was the main factor affecting the change of the pH value of the base material during the fermentation process of coffee grounds.(3)The addition of molasses and wheat bran significantly promoted the increase of the water-soluble protein,reducing sugar and alkaline hydrolysis nitrogen content of the coffee grounds fermentation base material.Compared with the control,the content of water-soluble protein,reducing sugar and alkaline hydrolysis nitrogen of each formula fermentation base material can increase up to 249.85%,284.27%and 90.30%.The addition ratio of wheat bran is the main influencing factor that affects the water-soluble protein,reducing sugar and alkaline hydrolysis nitrogen content of coffee grounds fermentation base material.(4)According to the different formulas of coffee grounds,each index value of the fermentation base material was processed,and the three kinds of bacteria fermentation formulas were optimized and screened by a comprehensive scoring method.The results showed that the optimal formulas of lactic acid bacteria and Trichoderma harzianum were molasses concentration 1%,wheat bran ratio 6%,and inoculation amount 3%;yeast optimal formula:molasses concentration 2%,wheat bran ratio 6%,inoculation amount 3%.2.According to the dynamic changes of the coffee grounds fermentation process indicators,the relatively optimized formula(263)and the control formula(001)of the 9 formulas were selected for a 40-day earthworm breeding experiment.The dynamic changes of ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium and pH value of the base material in the digestion process were tracked and determined,and the growth and reproduction status of earthworms in the fermentation base material of each treatment after the digestion was completed.The results showed(1)Compared with the control fermentation base,the total number of earthworms in the optimized formula fermentation base increased by 68.05%?79.14%.the number of adult earthworms increased by 29.66%?52.99%,and the number of young earthworms increased by 145.45%?184.95%.Compared with yeast and Trichoderma harzianum,lactic acid bacteria fermentation base material is more conducive to the survival and adaptation of earthworms,and promotes the digestion of coffee grounds fermentation base material and the growth and reproduction of earthworms(2)The concentration ranges of ammonium nitrogen and nitrate nitrogen after the fermentation base material is digested by earthworms are 33.79?243.31 ppm and 420.99?1347.96 ppm,respectively.Earthworm digestion generally increases the concentration of ammonium nitrogen and nitrate nitrogen in the fermentation base material,and the optimized fermentation base material of coffee grounds formula is more conducive to the release of ammonium nitrogen and nitrate nitrogen(3)The content of available phosphorus and available potassium reached 1919.83?2209.21 ppm and 4123.51?6065.74 ppm after the earthworm digestion of different treatments for 40 days.In addition,the content of available phosphorus and available potassium of the optimized formula fermentation base material has been greatly improved compared with that of the control treatment(4)The pH value of the coffee grounds fermentation base material is 4.80?6.04 after being digested by earthworms.The digestion process generally promotes the pH value of the fermentation base material to evolve from acidic to neutral.Compared with the control fermentation base material,the pH value of the optimized formula base material is closer to neutral after the earthworms are digested,which can provide a more suitable pH for the application of coffee grounds and earthworm manure as organic fertilizers and cultivation substrates.3.The lactic acid bacteria and Trichoderma harzianum fermented coffee dregs and vermicompost were used for rice seedling experiments,and the feasibility of using coffee dregs as a cultivation substrate after microbial fermentation+earthworm digestion was preliminarily studied.We also analyzed its influence on the establishment of bacterial communities in the rhizosphere of rice seedlings.The results showed:(1)Compared with the control substrate,lactic acid bacteria and Trichoderma harzianum fermented coffee grounds and vermicompost substrates increased the emergence rate of rice by 19.80%and 13.15%,respectively.The root dry matter weight increased by 200.91%and 208.26%,and the root dry matter weight per unit area increased by 261.04%and 249.35%,respectively.While the dry matter weight of seedlings was reduced by 21.29%and 21.73%,and the dry weight of seedlings per unit area was reduced by 5.71%and 11.53%,respectively.(2)Proteobacteria,Actinobacteria,Bacteroidetes,Chloroflexi,Firmicutes,Verrucomi-crobia,and Gemmatimonadetes dominated the rhizosphere bacterial communities of the three seedling substrates,which accounted for more than 93%of the total sequence abundance Compared with the control substrate.the lactic acid bacteria fermented coffee dregs and vermicompost substrates decreased the species richness and community diversity of rice rhizosphere bacteria,but the difference of Trichoderma harzianum treatment was not obvious(3)In terms of the function of rhizosphere bacteria,compared with the control substrate,the two microbial agents fermented coffee dregs and vermicompost substrates both promoted the increase of the abundance of potential growth-promoting bacteria in the rhizosphere of seedlings.The substrate of Trichoderma harzianum fermented coffee dregs and vermicompost obviously promoted the increase of the bacterial abundance related to the seedling rhizosphere and material circulation function.While the lactic acid bacteria fermented coffee grounds and vermicompost substrate significantly promoted nitrogen fixation in the rhizosphere of seedlings and increased abundance of anti-stress functional bacteria. |
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