Karakterisasi Seluler Mutan Osmotoleran Pichia kudriavzevii.

Abstract

Bioethanol is one of the largest renewable energy commodities in the world besides biodiesel. Industrial-scale bioethanol production utilize yeast Saccharomyces cerevisiae as a fermentation agent. However, this type of yeast has a limitation of being unable to use pentose sugar. The development of yeast that is able to use pentose opens one of the opportunities for utilization of lignocellulosic waste as a bioethanol fermentation substrate. Pichia kudriavzevii is known to be able to utilize pentose as a bioethanol fermentation substrate. Osmotic stress in bioreactors occurs because of the high concentration of sugar as a fermentation substrate. The development of P. kudriavzevii strain which is resistant to sugar osmotic stress is expected to increase the efficiency of the bioethanol production system. The construction of osmotolerant isolate was carried out using directed evolutionary mutagenesis technique which grew isolate in serial glucose concentrations from low state to maximum tolerance limits. This study aimed to construct the P. kudriavzevii osmotolerant mutant and analyze its cellular characteristics. Research on the construction of P. kudriavzevii osmotolerant mutant using direct evolution mutagenesis technique and analysis of alteration in cellular activity have never been done before. The results showed that the P. kudriavzevii osmotolerant mutant (Pku RM) was successfully constructed using directed evolutionary mutagenesis technique to hyperosmotic stress for up to 35% glucose (w/v) and was able to grow optimally at concentration of 25% (w/v). Mitochondrial activation in Pku RM was not significantly different from RWT Pku but was higher than Sce BY4741. These results indicate that Pku RM has the potential to be developed as a bioethanol fermentation agent related to its ability in dealing with osmotic stress.