Liquid Fermentation Technology And Transcriptomic Analysis Of Paecilomyces Lilacinus Invaded To Meloidogyn Eggs

Paecilomyces lilacinus is the most potential biocontrol materials for Meloidogyne threaten.At present,spores of P lilacinus are mostly produced by solid fermentation,with several problems such as long fermentation cycle and short shelf life.Relying on advantages of liquid fermentation,studies on sporulation fermentation and preparation of P lilacinus will be helpful to explore new production methods.In addition,the transcriptome sequencing and analysis for differential gene expression of Paecilomyces lilacinus invaded to Meloidogyn eggs will contribute to understanding of mechanism of P.lilacinus for Meloidogyne control.This study focused on P.lilacinus.Fermentation formula of P lilacinus was screened by using shaking flask culture;sporulation conditions and fermentation technology were determined by using fermenting in fermentation tanks;Effects of different carriers on preservation for spores of P lilacinus were compared,and the preservation methods for spores were explored.The transcriptome of P.lilacinus invaded to Meloidogyn eggs was sequenced using high-throughput sequencing technology,and then assembly and analysis was performed to explore change in gene expression between before and after invasion.The main results are presented as follows.1)The optimal C/N ratio of culture medium for P.lilacinus was 16:1,the optimal carbon source was sucrose,the optimal nitrogen source was soybean powder.The culture medium:sucrose of 56 g/L,soybean powder of 20 g/L,potassium dihydrogen phosphate of 2 g/L,anhydrous calcium chloride of 0.4 g/L,magnesium sulfate of 0.3 g/L,cobalt chloride of 0.037 g/L,iron sulfate of 0.05 g/l,manganese sulfate of 0.016 g/L,zinc sulfate of 0.014 g/L.2)Low dissolved oxygen was helpful for an efficient sporulation in P.lilacinus.Fermentation process:500 r/min;aeration ratio:0-24 h 1:1(V/V:aeration:liquid loading)24-72 h 2:1(V/V);temperature:28℃;pressure:0 MPa.The spore yield can reach up to 2.3 billion/mL.3)Method of passing 400 mesh sieve and 500 mesh sieve could remove mycelium,and centrifugation of 3500 r/min could effectively collect spores in fermented liquid.The spores of P.lilacinus could not be preserved for a long time,but preservation period could be prolonged by sealing the spores at 25℃ using the carrier of corn flour.4)Four thousand six hundred and ninety-nine DEGs were identified in the transcriptome of P lilacinus invaded to Meloidogyn eggs in comparison with control.Of these genes,2750 and 1949 were up-regulated and down regulated,respectively.Via gene ontology(GO)enrichment analysis of DEGs,18 categories belonging to biological process were significantly enriched,and they were primarily involved in organic acid catabolic process,single-organism catabolic process and,cellular amino acid catabolic process;10 categories belonging to molecular function were significantly enriched to be primarily associated with ascatal ytic activity,coenzyme binding,and oxidoreductase activity.Furthermore,via KEGG enrichment analysis of DEGs,two KEGG metabolic pathways were significantly obtained,including ribosome and valine,leucine and isoleucine degradation,which were related to biodegradation and synthesis of P.lilacinus in process of invasion to Meloidogyn eggs.This study explored the molecular mechanism of P.lilacinus invaded to Meloidogyn eggs,and explored the liquid fermentation and spore preparation of P.lilacinus,which will be conducive to the further industrial application of P.lilacinus.