Construction Of Biocontrol And Growth-promoting Microbial Agents Based On Atmospheric Pressure Room Temperature Plasma Mutagenesis Technology

With the large-scale development of modern agriculture,its ecological security issues are being increasingly valued.China urgently needs to promote the development of sustainable agriculture.While seeking high productivity and resource utilization efficiency,the harm caused by chemical fertilizers to the soil structure cannot be underestimated.Actively developing a microbial compound bacterial agent and using a microbial compound bacterial agent instead of traditional chemical fertilizers is one of the ideal strategies to achieve environmentally friendly agriculture.The content and results of this study are as follows.1.ARTP mutagenesis and fermentation optimization of antagonistic strain TXM-A2.In this study,ARTP was used to mutate B.amyloliquefaciens TXM-A2.By measuring the growth radius of Fusarium oxysporum Methods Screening was performed,and the genetic stability of the mutant strains was observed by continuous culture for 5 generations.Taking the OD₆₀₀ of the mutagenized strain and the inhibitory effect of the sterile filtrate on F.oxysporum as the detection indicators,the single-factor experiment was used to optimize the fermentation medium,and finally the fermentation process of the mutant strain was optimized.The results showed that a mutant strain AR7was screened,and the inhibitory effect on F.oxysporum was increased by 13.70%.After5 subcultures,the genetic stability of the mutant was good.The optimized seed medium formula is 0.5%glucose,0.5%Na Cl,2%yeast extract,p H 7.0±0.2,Under these conditions,the OD₆₀₀ of AR7 increased from 3.250 to 4.553,and the bacteriostatic diameter increased from 2.833 cm to 2.875 cm.AR7 was fermented in a 5 L fermenter,and its maximum viable count reached 1.2×10⁹ CFU·m L^-1.2.Germination of L.paracasei on vegetable seeds and analysis of metabolites.To investigate the effect of L.paracasei fermentation broth on seed germination,using cabbage and other vegetable seeds as materials,the changes of germination rate and germination potential of vegetable seeds after using different dilution times of L.paracasei fermentation broth were studied,combined with the determination of amino acids in the metabolites of L.paracasei fermentation broth,the corresponding analysis was made.The results show,When the fermentation liquid of L.paracasei was diluted1000 times,its viable count was about 2.3×10⁵ CFU·m L^-1,which could significantly improve the germination rate and germination potential of cherry radish seeds.Analysis of metabolites showed that L.paracasei can produce a variety of amino acids,its metabolites have a gibberellin content of 0.04%and a concentration of about 416mg·L^-1;an indoleacetic acid content of 0.002%and a concentration of about 3 mg·L^-1.3.Analysis of L.paracasei compound bacterial agent field performance and growth promotion effect.In this study,constructed a compound microbial inoculum of L.paracasei and S.cerevisiae,analyze changes in vegetable growth and soil microbial diversity.The results showed that the average plant height of chinese little greens and cherry radish after irrigation with L.paracasei increased by 8.53 cm and 10.2 cm,respectively.The soil bacterial community structure and composition were significantly different under different treatments.The mixed cultivation of S.cerevisiae and L.paracasei watered the crops,which not only improved the micro-ecological diversity of soil bacteria,but also had higher amino acids,indole acetic acid,and gibberella.It can also attract beneficial bacteria,which lays a foundation for the research on the technology and theory of crop growth promotion and stress resistance.