Effects Of Synthetic Flora And Biofilm Formation Ability On Cabbage Growth

Multi-species microbial agents play an important role in strengthening soil microflora,improving soil structure,crop resistance,and the quality of agricultural products.It is generally believed that one of the obstacles to the application of multispecies microbial agent is to maintain the existence of beneficial microorganisms in soil for a long time.The formation of biofilm not only facilitates the colonization and survival of microorganisms in the environment,but also promotes the symbiosis between different species,thus improving their environmental effects.Therefore,the ability of microorganisms to interact and form biofilms in multispecies agents may have a potential impact on their effectiveness.In order to reveal the internal relationship between biofilm formation and function of multispecies microorganisms,we preliminarily studied the effect of multispecies synthetic bacteria flora and their biofilm-forming ability on plant germination and growth.Ten strains of growth-promoting bacteria were selected as experimental materials,and a total of 385 synthetic bacteria strains were obtained through single strain combinations,two strains combinations,three strains combinations and four strains combinations.Firstly,the biofilm-forming ability of these bacteria strains was investigated,and then these synthetic bacteria strains were used to infect fast-growing cabbage seeds.The influence of bacterial community on plant germination(germination rate)and growth(plant weight)was measured.Finally,the relationship between the combinations of bacterial strains,biomass of biofilm,plant seed germination and growth were analyzed,and the following understanding was obtained:(1)Biofilm quantitative experiment results show that: Microbacterium sp.D12,Bacillus sp.KF11,Bacillus sp.CK22,Bacillus sp.CK1,Acinetobacter sp.G18,Bacillus sp.F19,Pseudomonas sp.G7,Bacillus sp.CMF18,Bacillus sp.CMF9,Sphingomonas sp.G5.Bacillus sp.CMF18 was the single strain that produced the largest biofilm biomass.As the number of species increased,the biofilm biomass increased first and then decreased,and the level of synthetic biofilm biomass was higher when the number of species was 2 and 3 than 4.(2)Respectively,when no strain was added,seed germination rate and seeding weight of per plant were 66.7% and 0.0449 g.In general,when the biofilm biomass was in the range of 0-3,the seed germination rate and per plant weight were significantly increased(for example,the biofilm biomass of CK1/CK22 was 0.7603,which germination rate was 83.3%,and per plant weight was 0.0665 g).When the biofilm biomass was greater than 3,the germination rate and per plant weight decreased with the increase of biofilm biomass(for example,the biofilm biomass of KF11/CK22/CMF18 was 3.1420,and germination rate and weight of per plant were both 0).Secondly,it was found that some combinations could significantly improve the plant to grow.For example,the combinations CK22/F19/G7/KF11,CK22/CMF9/G7 and CK22/G7 had good promotion effect on fresh weight and germination rate of cabbage.In conclusion,this study found that species specificity had a greater impact on seed germination and growth.Within a certain range,biofilm biomass promoted plant growth and development.While beyond this range,it inhibited seed germination and growth.The results of this study provide a useful reference for understanding the role of multispecies interactions,species number,species specificity and biofilm in plant growth.It also provides a scientific basis for improving bacterial activity and promoting bacterial function in multispecies agents.