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Biosynthesis of ZnO Nanoparticles by a New Pichia kudriavzevii Yeast Strain and Evaluation of Their Antimicrobial and Antioxidant Activities.

ABSTRACT: The potential ability of a new yeast strain, Pichia kudriavzevii, in the synthesis of zinc oxide nanoparticles (ZnO-NPs) through a green method was explored in this study. The effect of reaction time (12, 24 and 36 h) on the structure of the resulting ZnO nanoparticles was investigated. From the XRD and TEM results, the ZnO-NPs with a hexagonal wurtzite structure and a particle crystal size of ~10-61 nm was formed at different reaction times. Combing XRD, TEM, and PL results, it was revealed that the sample prepared at intermediate duration (24 h) has the most favorable nanosized structure with the lowest defect concentration. The biomedical properties of ZnO-NPs as free radical scavenging activity, cytotoxicity and antibacterial agents were characterized. Biosynthesized ZnO-NPs showed strong DPPH free radical scavenging and a dose dependent toxicity with non-toxic effects on Vero cells for concentrations below 190 µg/mL. Desirable bactericidal activity was shown by the ZnO-NPs on Gram-positive bacteria (Bacillus subtilis, Staphylococcus epidermidis and Staphylococcus aurous) and Gram-negative bacteria (Escherichia coli and Serratia marcescens). A maximum inhibition zone of ~19 mm was observed for Staphylococcus epidermidis at a concentration of 100 µg/mL for sample prepared at 24 h. The results from this study reveal that ZnO-NPs possesses potential for many medical and industrial applications.

SUBMITTER: Moghaddam AB

PROVIDER: S-EPMC6152784 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Biosynthesis of ZnO Nanoparticles by a New Pichia kudriavzevii Yeast Strain and Evaluation of Their Antimicrobial and Antioxidant Activities.

Moghaddam Amin Boroumand AB Moniri Mona M Azizi Susan S Rahim Raha Abdul RA Ariff Arbakariya Bin AB Saad Wan Zuhainis WZ Namvar Farideh F Navaderi Mohammad M

Molecules (Basel, Switzerland) 20170524 6

The potential ability of a new yeast strain, <i>Pichia kudriavzevii</i>, in the synthesis of zinc oxide nanoparticles (ZnO-NPs) through a green method was explored in this study. The effect of reaction time (12, 24 and 36 h) on the structure of the resulting ZnO nanoparticles was investigated. From the XRD and TEM results, the ZnO-NPs with a hexagonal wurtzite structure and a particle crystal size of ~10-61 nm was formed at different reaction times. Combing XRD, TEM, and PL results, it was revea ...[more]

PMID: 28538674

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Project description:Itaconic acid (IA), or 2-methylenesuccinic acid, has a broad spectrum of applications in the biopolymer industry owing to the presence of one vinyl bond and two acid groups in the structure. Its polymerization can follow a similar mechanism as acrylic acid but additional functionality can be incorporated into the extra beta acid group. Currently, the bio-based production of IA in industry relies on the fermentation of the filamentous fungus Aspergillus terreus. However, the difficulties associated with the fermentation undertaken by filamentous fungi together with the pathogenic potential of A. terreus pose a serious challenge for industrial-scale production. In recent years, there has been increasing interest in developing alternative production hosts for fermentation processes that are more homogenous in the production of organic acids. Pichia kudriavzevii is a non-conventional yeast with high acid tolerance to organic acids at low pH, which is a highly desirable trait by easing downstream processing. We introduced cis-aconitic acid decarboxylase gene (cad) from A. terreus (designated At_cad) into this yeast and established the initial titer of IA at 135 ± 5 mg/L. Subsequent overexpression of a native mitochondrial tricarboxylate transporter (herein designated Pk_mttA) presumably delivered cis-aconitate efficiently to the cytosol and doubled the IA production. By introducing the newly invented CRISPR-Cas9 system into P. kudriavzevii, we successfully knocked out both copies of the gene encoding isocitrate dehydrogenase (ICD), aiming to increase the availability of cis-aconitate. The resulting P. kudriavzevii strain, devoid of ICD and overexpressing Pk_mttA and At_cad on its genome produced IA at 505 ± 17.7 mg/L in shake flasks, and 1232 ± 64 mg/L in fed-batch fermentation. Because the usage of an acid-tolerant species does not require pH adjustment during fermentation, this work demonstrates the great potential of engineering P. kudriavzevii as an industrial chassis for the production of organic acid.

Dataset Information

Biosynthesis of ZnO Nanoparticles by a New Pichia kudriavzevii Yeast Strain and Evaluation of Their Antimicrobial and Antioxidant Activities.

Publications

Biosynthesis of ZnO Nanoparticles by a New Pichia kudriavzevii Yeast Strain and Evaluation of Their Antimicrobial and Antioxidant Activities.

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