Evolutionary Adaptation of Kluyveromyces marxianus NIRE-K3 for Enhanced Xylose Utilization

Abstract

The evolutionary adaptation was approached on the thermotolerant yeast Kluyveromyces marxianus NIRE-K3 at 45°C on xylose as a sole source of carbon for enhancement of xylose uptake. After 60 cycles, evolved strain K. marxianus NIRE-K3.1 showed comparatively 3.75-and 3.0-fold higher specific growth and xylose uptake rates, respectively, than that of native strain. Moreover, the short lag phase was also observed on adapted strain. During batch fermentation with xylose concentration of 30 g l −1, K. marxianus NIRE-K3.1 could utilize about 96% of xylose in 72 h and produced 4.67 and 15.7 g l −1 of ethanol and xylitol, respectively, which were 9.72-and 4.63-fold higher than that of native strain. Similarly, specific sugar consumption rate, xylitol, and ethanol yields were 5.07-, 1.15-, and 2.44-fold higher as compared to the native strain, respectively. The results obtained after evolutionary adaptation of K. marxianus NIRE-K3 show the significant improvement in the xylose utilization, ethanol and xylitol yields, and productivities. By understanding the results obtained, the significance of evolutionary adaptation has been rationalized, since the adapted culture could be more stable and could enhance the productivity.

Production of Some Higher Alcohols and Acetate Esters from Rice Bran by Yeasts Metabolisms of Kluyveromyces Marxianus and Debaryomyces Hansenii

“…The researchers determined that the growth rates varied between 0.8/h and 1.06/h depending on the fermentation temperature for these strains in the bioethanol production from lignocellulosic hydrolysates. Compared to our ndings, lower growth rates for K. marxianus and D. hansenii were also reported by previous studies [24,25]. In a study by Madawati et al [24], the growth rate for D. hansenii was determined between 0.03/h and 0.06/h in arabitol production from by-products of Reutalis trisperma biodiesel.…”

“…In a study by Madawati et al [24], the growth rate for D. hansenii was determined between 0.03/h and 0.06/h in arabitol production from by-products of Reutalis trisperma biodiesel. Similarly, Sharma et al [25] reported 0.02/h of growth rate for K. marxianus NIRE-K3 (MTCC 5934) in the YEPX medium with xylose (3%) medium at 45°C. Overall, it can be concluded that variation in growth rates of K. marxianus and D. hansenii results from strain type, utilization behavior of substrate by the microbial strains, agro waste types and its physicochemical structure and fermentation conditions.…”

Synergistic Enzyme Cocktail to Enhance Hydrolysis of Steam Exploded Wheat Straw at Pilot Scale

“…has been investigated to quantitatively evaluate their impact on hydrolysis of steam pretreated wheat straw (SEWS) at pilot scale. This work established the hypothesis that accessory enzymes have a critical role in biomass hydrolysis and their optimization is a significant tool to enhance fermentable sugar production (Sharma et al, 2017). Further, the in-house developed enzyme mixture (EnzMix) was benchmarked with the latest commercial enzyme preparations of the leading manufacturers.…”

Screening and Growth Characterization of Non-conventional Yeasts in a Hemicellulosic Hydrolysate

“…The glucose catabolite repression is considered one of the main challenges for efficient utilization and co-consumption of the diverse substrates in lignocellulosic hydrolysates ( Hua et al, 2019 ; Simpson-Lavy and Kupiec, 2019 ). Metabolic engineering and adaptive laboratory evolution (ALE) have been used to alleviate the glucose catabolite repression in S. stipitis and K. marxianus ( Slininger et al, 2015 ; Sharma et al, 2017 ; Hua et al, 2019 ; Kim et al, 2019 ). Different than expected based on the initial screening experiments, L. starkeyi DSM 70295 did not demonstrate a co-consumption of glucose and xylose but showed a preference to consume glucose and acetic acid first.…”