Effects of Plant Growth Hormones on Mucor indicus Growth and Chitosan and Ethanol Production.

Zahra Safaei,Poorandokht Golkar,Akram Zamani,Keikhosro Karimi

doi:10.3390/ijms160716683

Zahra Safaei, Poorandokht Golkar + Show 2 more

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https://doi.org/10.3390/ijms160716683

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Abstract

The objective of this study was to investigate the effects of indole-3-acetic acid (IAA) and kinetin (KIN) on Mucor indicus growth, cell wall composition, and ethanol production. A semi-synthetic medium, supplemented with 0–5 mg/L hormones, was used for the cultivations (at 32 °C for 48 h). By addition of 1 mg/L of each hormone, the biomass and ethanol yields were increased and decreased, respectively. At higher levels, however, an inverse trend was observed. The glucosamine fraction of the cell wall, as a representative for chitosan, followed similar but sharper changes, compared to the biomass. The highest level was 221% higher than that obtained without hormones. The sum of glucosamine and N-acetyl glucosamine (chitin and chitosan) was noticeably enhanced in the presence of the hormones. Increase of chitosan was accompanied by a decrease in the phosphate content, with the lowest phosphate (0.01 g/g cell wall) being obtained when the chitosan was at the maximum (0.45 g/g cell wall). In conclusion, IAA and KIN significantly enhanced the M. indicus growth and chitosan production, while at the same time decreasing the ethanol yield to some extent. This study shows that plant growth hormones have a high potential for the improvement of fungal chitosan production by M. indicus.

Highlights

Due to the irreversible negative impacts of petroleum-based products on the environment as well as the limited petroleum resources available today, finding renewable alternatives for these products is among the strategic goals of various countries [1]
The objective of the current work was to investigate the effect of two types of plant growth hormones, indole-3-acetic acid (IAA) and kinetin (KIN), on chitosan and ethanol production by M. indicus in a semi-synthetic medium usually used for ethanol production
The results of the current study showed that plant hormones can significantly improve the fungal chitosan production

Summary

Introduction

Due to the irreversible negative impacts of petroleum-based products on the environment as well as the limited petroleum resources available today, finding renewable alternatives for these products is among the strategic goals of various countries [1]. Biofuels and biopolymers are examples of the renewable materials, which play crucial roles in the development of sustainable societies for the future. Ethanol is among the most important of biofuels, in terms of production volume. Nowadays, this biofuel is mainly produced by Saccharomyces cerevisiae [2]. There are some other microorganisms such as Mucor indicus, which produce ethanol with comparable productivities and yields. M. indicus, which was discovered several hundred years ago, is a zygomycete fungus that recently has received a lot of attention for ethanol production from lignocellulosic hydrolyzates. Simultaneous production of ethanol and chitosan from hexoses and pentoses is among the most important benefits of the fungus over S. cerevisiae [3,4,5]

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