Transcriptional analysis of Kluyveromyces marxianus for ethanol production from inulin using consolidated bioprocessing technology

Abstract

BackgroundEthanol production from non-crop materials, such as Jerusalem artichokes, would make a great contribution to the energy industry. The non-conventional yeast, Kluyveromyces marxianus, is able to carry out ethanol fermentation of sugar molecules obtained from inulin-containing materials by consolidated bioprocessing. Lower inulin concentrations and micro-aeration can lead to a relatively fast and ideal fermentation process; however, it is unclear what causes the inhibition of higher concentrations of inulin and the promotion effect of aeration.ResultsNext-generation sequencing technology was used to study the global transcriptional response of K. marxianus Y179 under three fermentation conditions, including 120 g/L inulin without aeration (120-N), 230 g/L inulin without aeration (230-N), 230 g/L inulin with aeration by ORP controlling at −130 mV (230-130mV). A total of 35.55 million clean reads were generated from three samples, of which 4,820 predicted that open reading frames were annotated. For differential expression analysis, 950 and 1,452 differentially expressed genes were discovered under the conditions of 230-130mV and 120-N, respectively, and the sample 230-N was used as the control. These genes are mainly associated with the pathways of central carbon metabolism and ethanol formation. Increased expression of inulinase and the low activity of the autophagy-related gene, ATG8, ensured fast and ideal fermentation processes.ConclusionsDespite being reported as the “crabtree-negative” species, K. marxianus Y179 could achieve favorable ethanol fermentation profiles under micro-aeration and high inulin concentrations. K. marxianus Y179 cells responded to inulin concentrations and micro-aeration that is involved in the whole ethanol metabolism network. These results will serve as an important foundation for further exploration of the regulatory mechanisms involved in ethanol fermentation from inulin by consolidated bioprocessing and also provide a valuable reference for future studies on optimization and reconstruction of the metabolism network in K. marxianus.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0295-y) contains supplementary material, which is available to authorized users.

Transcriptomic analysis of thermotolerant yeastKluyveromyces marxianusin multiple inhibitors tolerance

“…In the case of unconventional thermotolerant yeast K. marxianus, however, there were only several reports of transcriptome analysis on yeast responses from different carbon source including glucose, inulin and xylose, or the tolerance to high temperature or ethanol stress. 18,69,70,71 To the best of our knowledge, genome-wide transcription analysis under the multiple inhibitors stress condition with elevated temperature (42 C) has not been reported for this yeast.…”

Enhanced fermentative performance under stresses of multiple lignocellulose-derived inhibitors by overexpression of a typical 2-Cys peroxiredoxin from Kluyveromyces marxianus

“…Expression pattern analysis of differentially expressed genes related to oxidative stress from transcriptome of K. marxianus Y179 [20] was clustered using Cluster software [39] and Java TreeView software [40]. The hierarchical clustering of the chosen experimental conditions and genes was carried out using Euclidean Distance as the formula of the distance matrix.…”

“…Our previous study on the transcriptional analysis of the non-conventional yeast Kluyveromyces marxianus , which possesses the advantages of high-temperature resistance, rapid growth rate, and diversity of substrates, identified lots of differentially expressed genes (DEGs) [20]. A greatly up-regulated gene under aerobic conditions (ORP controlled at −130 mV) from K. marxianus Y179 has attracted our attention.…”

Production of bioethanol from lignocellulosic banana peduncle waste using Kluveromyces marxianus

“…Kluveromyces marxianus IMB strain in simultaneous saccharification and fermentation shows favorable yield between 40 to 50°C (Faga et al, 2010). K. marxianus Y179, yields -1 maximum ethanol of 98 g l at 30°C (Gao et al, 2015).This thermophilic and ethanogenic specie cab be used in simultaneous saccharification and fermentation for ethanol production for limiting the cost of overall process (Choudhary et al, 2016;Murata et al, 2015;Raja Sathendra et al, 2019). Thus in the present study, high thermo tolerance K. marxianus species was used for the production of bioethanol.…”