Biodiversity Of Aspergillus Section Flavi From Corn In Guangxi And Alleviation Of Mycotoxin Contamination Via Engineered Composite Materials

Guangxi province located in the southwest is one of the largest corn zones of China.Due to the hot and humid weather here,corn is susceptible to aflatoxin contamination.Hence,a polyphasic study to investigate Aspergillus section Flavi population in Guangxi was needed,which may affect prevention and control strategies of fungi and mycotoxins in this region.The present study was aimed at the monitoring of toxigenic Aspergillus section Flavi species from corn in Guangxi Zhuang autonomous region and to propose some mycotoxins mitigation strategies.The entire study was divided into four major parts,i.e.,[1]Applying a polyphasic approach to identify the Aspergillus section Flavi population structure in corn kernels and their potential to produce different mycotoxins,[2]Fabrication of an organic-inorganic hybrid bentonite composite by using orange peel extract to sequester selected mycotoxins from aqueous solution and gastrointestinal fluids,[3]Synthesis of nature mimic bentonite composite by employing an organic acid(Tannic acid)to adsorb aflatoxins from buffer solution and[4]Employing cherry and blueberry pomace for the removal of aflatoxins from aqueous solution,gastrointestinal fluids and model wine.In the first step,a total of 195 isolates of Aspergillus section Flavi were isolated from corn kernels,and a polyphasic approach was applied for their identification,molecularly by employing three sets of primer pairs ITS,BenA and CaM,chemo-toxically by detecting different mycotoxins with the use of HPLC and LCMS and morphologically by studying their growth on different culture media at different temperatures and by recording microscopic observations.Studied section Flavi population comprised of Aspergillus flavus(192/195),Aspergillus arachidicola(1/195),Aspergillus pseudonomius(1/195)and Aspergillus novoparasiticus(1/195).Aspergillus flavus strains produced diversified chemotypes based on their mycotoxin production,but all other species were very consistent in their toxigenic profile,i.e.,they produce all four aflatoxins but no cyclopiazonic acid.Aspergillus flavus isolates could produce elevated amounts of CPA in combination with AFs,which emphasized on the intrusion of CPA into surveys of toxigenic mycobiota.To address mycotoxins mitigation,first,an organic-inorganic hybrid bentonite material was fabricated by modifying the interlayer structure of bentonite with ethanol,methanol,and water extracts of dried orange peels.The prepared material was employed for the sequestration of selected mycotoxins[aflatoxin B1(AFB1),ochratoxin(OTA),and fumonisin b1(FB1)].Different material characterization techniques such as BET,FT-IR,XRD,TGA,SEM,EDX,and XPS were employed to characterize the fabricated material.For the sequestration of mycotoxins,different analytical parameters for the adsorption process were studied,which includes pH,dosage,and kinetics.Adsorption isothermal studies were conducted in buffer solution(pH 2.5 and 7)and gastrointestinal fluids,which revealed the maximum adsorption capacity(mg/g)of 166 and 121 for AFB1,3.87 and 1.78 for FB1 and 1.97 and 3.19 for OTA respectively.The proposed organic-inorganic hybrid material could efficiently adsorb selected mycotoxins in the single and muti-mycotoxins system.Adsorptive removal of four aflatoxins(AFB1,AFB2,AFG1,and AFG2)from aqueous solution was performed by nature mimic material which was synthesized by the modification bentonite with a nature-derived acid(tannic acid).Fabricated material was characterized by employing all the above-mentioned material characterization techniques,and the parameters for the adsorption reaction(pH,dosage,kinetics,thermodynamics)were standardized.Different environmental factors that could affect the adsorption reaction in practical conditions were also studies,which include the effect of metals(heavy and essential),humic acid,wastewater,and co-occurrence of aflatoxins.Isothermal studies of the selected aflatoxins expressed the maximum Langmuir adsorption capacity(mg/g)of 86,71,74,and 149 mg/g for AFB1,AFB2,AFG1,and AFG2 respectively.Adsorption in the multi-aflatoxin system revealed that adsorptive removal of selected aflatoxins was not affected in the simultaneous presence of all four aflatoxins.In the final step,aflatoxins mitigation by cherry and blueberry pomace was proposed,which would provide the ecofriendly mitigation of aflatoxins and the recycling of fruit industry waste as well.Cherry and blueberry pomaces were used as raw,and their fermentation was also carried out to extend the scope to wine industry waste utilization.After material characterization,different parameters for the adsorption reaction were optimized.To extend the application of the proposed biosorbent,adsorption reactions were also performed in gastrointestinal fluids and model wine as well.The proposed biosorbent exhibited rapid kinetics with the exothermicity of the adsorption reaction.The adsorption rate was slightly decreased in model wine due to the presence of ethanol,while the adsorption in intestinal fluid exhibited an elevated adsorption rate than that of buffer solution.The fitting of isothermal data with different models exhibited the trend as follows;Sips>Langmuir>Freundlich,where the theoretical maximum adsorption capacity calculated from the Sips model remained 4.6,2.9,2.7 and 2.4 mg/g for AFB1,AFB2,AFG1,and AFG2 respectively.Conclusively,the present study provides an insight into the applicability and suitability of the polyphasic approach to study the biodiversity of toxigenic members of the section Flavi and highlights the different approaches for the adsorptive removal of mycotoxins and their potential applications in the food industry and biological system.