Isolation And Screening Of Growth-promoting Bacteria Of Pleurotus Eryngii And Study Of Its Growth-promoting Mechanis

Mushroom growth promoting bacteria(MGPB)are a kind of beneficial bacteria that exist inside or outside of mushroom and promote the growth and development of mushroom.They affect the life activities of mushroom through their own headspace compounds or soluble compounds or attached to the hyphae of mushroom.However,at present,the research of MGPB is relatively less than plant growth promoting rhizobacteria(PGPR).So the purpose of this study is to obtain the bacteria that can promote the growth of Pleurotus eryngii,and to explore the growth-promoting characteristics and mechanism of MGPB from four points: the ability to solubilize phosphate,the ability to produce IAA,siderophore and ACC deaminase,In addition,the growth of mycelia in tube and mushroom cultivation were tested by Pleurotus eryngii substrate to judge the growth-promoting effect of MGPB on Pleurotus eryngii in the actual cultivation materials.The main results and conclusions are as follows:First of all,a total of 118 strains of bacteria were obtained from 17 samples of cultivation materials.Then they were cultured with Pleurotus eryngii hyphae for "parallel line" and "cross" treatments symbiosis experiments,and then they were cultured in liquid with Pleurotus eryngii hyphae.Finally,four strains of bacteria were identified as Pseudomonas lactis FHX1,Pseudomonas costantinii FHX3,Ewingella americana FHX6 and Pseudomonas migulae LMJ4.Secondly,we tested the growth-promoting characteristics and mechanism of the four strains of bacteria,and we found they produced different headspace compounds or soluble compounds,so the growth-promoting characteristics of them are also different,which can play different positive role in mushroom growth.The four strains of MGPB have different abilities to solubilize phosphate,produce IAA,siderophore and ACC deaminase,therefore,they have different ways to promote the growth of mushroom.The MGPB’ s products of promoting mushroom growth play an important role in the ways of growth promotion.Strain FHX6 has excellent performance in phosphorous dissolving and ACC deaminase production,especially in IAA production,but was relatively weak in siderophore production.Strain FHX1,FHX3 and LMJ4 has excellent abilities of solubilizing phosphate and producing siderophore,while it has weak abilities of producing IAA and ACC deaminase.Finally,we tested the promoting effect of 4 MGPB by the tube mycelia experiments and mushroom emergence experiments by Pleurotus eryngii substrate.In the experiment of "tube mycelia growth",the bacterial culture broths of four strains of bacteria had obvious ability to promote the growth rate of mycelia.However,the growth-promoting ability of cell-free supernatants was not obvious,the reason may be that the bacteria can promote the growth and development by other ways,or the addition level of the cell-free supernatants was too low.The results of "mushroom emergence experiment" showed that the four strains of bacteria played a different role in promoting growth in the experiment of Pleurotus eryngii.The bacterial culture broths and cell-free supernatant of FHX1 had a certain promoting effect on mycelial growth,primordium formation and mushroom bud formation,but there had no obvious promoting effect on yield.The bacterial culture broths and cell-free supernatant of FHX3 had a certain promoting effect on the growth of mycelia and fruiting body,and the cell-free supernatant of FHX3 shortened the time of primordium formation significantly.The bacterial culture broths of FHX6 had obvious promoting effect on yield.LMJ4 did not show the effect of promoting growth in the early mycelia growth process,but its cell-free supernatant treatment group had obvious effect on shortening the time of primordium formation,promoting the development of mushroom buds and increasing the yield.And the overall infection rate of molds is very low(just one case),which may be related to the fact that all four strains of bacteria can produce siderophore.In this study,we found four new strains of bacteria with growth promoting ability to mushroom.They showed a good growth-promoting effect,which laid a foundation for production of MGPB into biological agents to instead of chemical agents into mushroom cultivation in the future.