Application Of Phanerochaete Chrysosporium For Lipid Production And Derivative Adsorbent Through Solid Fermentation

In this paper,a stable and cost-effective static solid cultivation method(SSC)is developed.Compared with the traditional submerged cultivation(SC),microbial lipid can be produced by this cultivation method,and during the cultivation of Phanerochaete chrysosporium chlamydospores,no aerator,agitator and temperature control system was necessary.And after the extraction of lipid,the solid residue is washed,dried and ground to obtain the P.chrysosporium adsorbent,which is suitable to treat dyeing wastewater.This study provides a set of solutions for the overall utilization of solid fermentation products from P.chrysosporium,and the main results are as follows:(1)A series of single factor affecting lipid production are optimized during SSC of P.chrysosporium.The optimal lipid production conditions are determined to be 4.5 g of glucose,no additional nitrogen source,initial pH 4.5,temperature 33?,hyphae inoculation weight 10 g,sealing time of breathable sealing film 3 d,and total incubation time 12 d.As a result,10.615 g biomass is obtained,and the highest oil production rate reaches 29.857%.(2)SSC and traditional liquid fermentation cultivation of P.chrysosporium simultaneously are carried out in lipid production experiments.The highest oil production rate of SSC is 2.24 times of that of SC,and during SSC,no cooling water circulation system,electrical equipment including aerators,agitators and temperature control systems was used,which means that this process only produces a small amount of reactor operation cost as well as the engineering feasibility is very high.The lipid conversion rate of the mat formed by SSC is up to 0.299 g/g that is almost up to the theoretical lipid conversion rate of microorganisms(0.310 g/g).(3)Metabolomics analysis shows that fatty acid composition of SSC is relatively simpler than that of traditional liquid fermentation,and the fatty acids from SSC contain a higher proportion of saturated fatty acids(90%)and long-chain fatty acids(93.6%)than that from SC.The fatty acids obtained by SSC mainly include pentadecanoic acid(29.1%),myristic acid(14.4%),lauric acid(14.8%)and arachidic acid(11.5%).(4)Twelve samples obtained from different culture methods and different time points of P.chrysosporium are sequenced on the Illumina platform,and 82.45 G sequencing datas are obtained.The differently expressed genes involved in glycerolipid metabolism(18 DEGs)and fatty acid elongation(5 DEGs)were enriched into samples T2 versus Ck2.The genes coding enoyl-CoA hydratase(EC: 4.2.1.17)and mitochondrial trans-2-enoyl-CoA reductase(EC: 1.3.1.38)were significantly up-regulated,and the upregulated genes explain why the saturated long chain fatty acids are synthesized in large quantities in chlamydospores.The down-regulated gene coding 3-ketoacyl-CoA synthase(EC: 2.3.1.199)reveals why pentadecanoic acid(C15)and myristic acid(C14)accounting for 45% of total lipids were accumulated.(5)After the lipid extraction,the P.chrysosporium adsorbent prepared with residue has a good adsorption performance on Congo red,Acid blue 90 and Acid green 9,and the adsorption process is in line with both the Freundlich adsorption isotherm and the pseudo-second-order kinetic equation.(6)The SEM observation reveals that there are a lot of rough and irregular grooves and micropores on the surface of the adsorbent,and the surface of adsorbent is smooth and dense after adsorption of dyes.The FTIR results show that the surface of the adsorbent contained a large number of positively charged amino groups,non-charged methyl,methylene groups,carbonyl groups with a positive charge of a carbon atom,and carboxyl groups,etc.,and after dye adsorption,the peak shape of the adsorbent is substantially unchanged.The results of X-ray diffraction pattern show that the adsorbent is mainly an amorphous structure with some properties similar to graphene oxide,and the diffraction pattern of dye adsorption shows that the dye has not changed its structure.The results of zeta potential show that the surface of the adsorbents is positively charged,and the chemical adsorption process occurs during adsorption.