Bacillus Hitwh-BA2 Fermented Kelp Residue Microbial Fertilizer And Biocontrol Of Aflatoxin Contamination

Ecological control of plant disease is one important measure in green production process that is one of theoretical basis to utilize non-toxic organic solid wastes. It pays more attention to plant’s own initiative, the interaction between plants and theenvironment, and the safety of food and environment. Fertilizing organic microbial fertilizer and adjusting the soil p H value are two effective ecological control measures.This study is about screening and identifying aflatoxin biocontrol bacteria, determining soil suppressive activity, producing kelp residue microbial fertilizer and utilizing residue microbial fertilizer to improve soil p H value and soil anti pathogens activity and peanut growth. This study provides reference to kelp residue utilization and ecological control of plant disease by using kelp residue microbial fertilizer.A norsolorinic acid(NA) mutant of Aspergillus parasiticus, A. parasiticus NFRI-95, short as A. parasiticus 95 was used in this research. The method of Tip-culture was used to determine the 60 isolates’ ability against A. parasiticus 95 in growth inhibition and aflatoxin production inhibition qualitatively and quantitatively. Isolates were identified. Bacillus sp strains with high resistance against A. parasiticus 95 activity were selected for peanut germination test. According to results of peanut germination tests and phytohormones detection, Bacillus amyloliquefaciens strain JGA2(-5)27-2 was selected to produce kelp residue microbial fertilizer. And this strain was named B. amyloliquefaciens strain Hitwh-BA2. The B. amyloliquefaciens strain Hitwh-BA2 not only has high ability against A. parasiticus95 in growth inhibition(84.44%) and aflatoxin production inhibition(100%), but also promote peanut germnation rate, with high rate of 76.00%, and produce phytohormone 6-KT.B. amyloliquefaciens strain Hitwh-BA2 with many PGPR features of high resistanceagainst A. parasiticus 95 activity and productionof phytohormone 6-KT can be used for producing organicmicrobial fertilizer. And the organicmicrobial fertilizer hasgood potential application prospect on ecological prevention and control of plant disease.Kelp residue contains a large number of organic compounds and alkali metal ions, which can be used for production of kelp residue microbial fertilizer and soil p H adjustment agent. Single factor experiment, climbing experiment and response surface methodology were used to optimize the kelp residue microbial fertilizer fermentation conditions. The optimal fermentation conditions: kelp residue concentration, the optimal sucrose concentration, KNO3 concentration, incubate time, moisture content, temperature, inoculation amount, p H values were 37.402%, 2.091%, 0.507%, 8.24 d(8 d 6 h), 60%, 35 ℃, 4%, and natural p H, respectively. The growth inhibition of kelp residue microbial fertilizer under optimal fermentation conditions was 72.23%. Kelp residue microbial fertilizer has good storage stability, with 3.1×1010 living bacteria after 6 months. The number of living bacteria and growth inhibition were reduced by 18.42% and 0.33%.Kelp residue microbial fertilizer was used to promote soil p H value and soil anti pathogens activity. Results indicated that kelp residue microbial fertilizer had significantly increased soil p H value and soil anti pathogens activity. And 20 g kelp residue microbial fertilizer for each pot was effective. Peanut pot experiment also showed that kelp residue microbial fertilizer had significantly increased soil anti pathogens activity, increased by 37.67% compared with CK. At the same time, the results also indicated that using Tip-culture method to determine soil leachate suppressive activity to characterize the soil suppressive activity is feasible.The effect of kelp residue microbial fertilizer on promoting peanut growth and inhibiting aflation infection was studied. Results showed that kelp residue microbial fertilizer had significantly promoted peanut yield, extremely significantly reduced the number of Aspergillus parasiticus 95, and lowered the peanut aflation infection rate to less than that of CK.Characteristics of kelp residue and biocontrol bacteria were combined by producing kelp residue microbial fertilizer. Kelp residue microbial fertilizer not only had ability to enrich soil, promote peanut yield, but also increased soil p H value and soil anti pathogens activity. So the kelp residue microbial fertilizer has potential application prospect on ecological prevention of plant diseases.