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Improved production of kojic acid by mutagenesis of Aspergillus flavus HAk1 and Aspergillus oryzae HAk2 and their potential antioxidant activity.

ABSTRACT: Two wild-type (WT) Aspergillus strains, A. flavus HAk1 and A. oryzae HAk2, were selected for kojic acid (KA) biosynthesis. Malt extract sucrose culture medium (MES) was the best culture medium for maximum production of KA. The maximum production of KA has been estimated at pH 4 after 7 days of incubation at 30 °C. Overproduction of KA was attained by mutagenesis of both A. flavus HAk1 and A. oryzae HAk2 through their exposer to different doses of gamma irradiation. The mutant strains (MT) A. flavus HAk1-M2 and A. oryzae HAk2-M26 were the most stable mutants for maximum production of KA through four generations. Yield of KA by A. oryzae HAk2-M26 and A. flavus HAk1-M2 has been 2.03-fold and 1.9-fold, respectively, higher than their wild-type strains. All WT and MT strains were used for KA production from different agricultural raw materials. Apple peel was the best waste for KA production by WT strains of A. flavus and A. oryzae, while orange peel and rice stalk are best material for KA production by MT strains, A. flavus HAk1-M2 and A. oryzae HAk2-M26, respectively. All experimental strains have the ability to produce considerable amounts of KA from sugarcane molasse (SCM) and sugar-beet molasse (SBM). SBM was better than SCM for KA production by all strains. The antioxidant activity of biosynthesizing KA was strongly affected with production conditions, where the highest antioxidant activity of all strains was recorded at the optimum environmental and nutritional conditions for KA production.

SUBMITTER: Ammar HAM

PROVIDER: S-EPMC5544602 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Improved production of kojic acid by mutagenesis of Aspergillus flavus HAk1 and Aspergillus oryzae HAk2 and their potential antioxidant activity.

Ammar Hala A M HAM Ezzat Saeid M SM Houseny Asmaa M AM

3 Biotech 20170804 5

Two wild-type (WT) Aspergillus strains, A. flavus HAk1 and A. oryzae HAk2, were selected for kojic acid (KA) biosynthesis. Malt extract sucrose culture medium (MES) was the best culture medium for maximum production of KA. The maximum production of KA has been estimated at pH 4 after 7 days of incubation at 30 °C. Overproduction of KA was attained by mutagenesis of both A. flavus HAk1 and A. oryzae HAk2 through their exposer to different doses of gamma irradiat ...[more]

PMID: 28794931

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Project description:BACKGROUND:Obesity and its related diseases are increasing worldwide. One of the best therapeutic strategies for obesity management is through the inhibition of pancreatic lipase (PL) enzyme. So far orlistat is the only FDA approved PL inhibitor, but with unpleasant side effects. New efficacious anti-obesity drugs are needed to achieve a successful reduction in the incidence and prevalence of obesity. Many microbial metabolites have PL inhibitory activity. Screening soil inhabitants for PL inhibitors could help in increasing the available anti-obesity drugs. We aimed to isolate and identify alternative PL inhibitors from soil flora. RESULTS:We screened the crude mycelial methanolic extracts of 39 soil samples for PL inhibitory activity by the quantitative lipase colorimetric assay, using the substrate p-nitrophenyl palmitate and orlistat as positive control. AspsarO, a PL inhibitor producer, was isolated from an agricultural field soil in Giza, Egypt. It was identified as Aspergillus oryzae using colony morphology, microscopical characteristics, 18S rDNA sequencing, and molecular phylogeny. Increasing the PL inhibitor activity, in AspsarO cultures, from 25.9?±?2% to 61.4?±?1.8% was achieved by optimizing the fermentation process using a Placket-Burman design. The dried 100% methanolic fraction of the AspsarO culture had an IC50 of 7.48??g/ml compared to 3.72??g/ml for orlistat. It decreased the percent weight gain, significantly reduced the food intake and serum triglycerides levels in high-fat diet-fed Sprague-Dawley rats. Kojic acid, the active metabolite, was identified using several biological guided chromatographic and 1H and 13C NMR techniques and had an IC50 of 6.62??g/ml. Docking pattern attributed this effect to the interaction of kojic acid with the key amino acids (Lys80, Trp252, and Asn84) in PL enzyme binding site. CONCLUSION:Combining the results of the induced obesity animal model, in silico molecular docking and the lipase inhibitory assay, suggests that kojic acid can be a new therapeutic option for obesity management. Besides, it can lower serum triglycerides in obese patients.

Dataset Information

Improved production of kojic acid by mutagenesis of Aspergillus flavus HAk1 and Aspergillus oryzae HAk2 and their potential antioxidant activity.

Publications

Improved production of kojic acid by mutagenesis of <i>Aspergillus flavus</i> HAk1 and <i>Aspergillus oryzae</i> HAk2 and their potential antioxidant activity.

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