High‐throughput sequencing reveals adaptation‐induced mutations in pentose‐fermenting strains of Zymomonas mobilis

Abstract

Zymomonas mobilis is capable of producing ethanol at high rates and titers from glucose. This bacterium has previously been engineered to consume the pentose sugars xylose and arabinose, but the rate of consumption of these sugars is low. Recent research has utilized adaptive evolution to isolate strains of Z. mobilis capable of rapidly fermenting xylose. In this study, we also used adaptive evolution to isolate strains of Z. mobilis capable of rapidly fermenting xylose and arabinose. To determine the bottlenecks in pentose metabolism, we then used high-throughput sequencing to pinpoint the genetic changes responsible for the phenotypes of the adapted strains. We found that the transport of both xylose and arabinose through the native sugar transporter, Glf, limits pentose fermentations in Z. mobilis. We also found that mutations in the AddB protein increase plasmid stability and can reduce cellular aggregation in these strains. Consistent with previous research, we found that reduced xylitol production improves xylose fermentations in Z. mobilis. We also found that increased transketolase activity and reduced glyceraldehyde-3-phosphate dehydrogenase activity improve arabinose fermentations in Z. mobilis. Biotechnol.

Controlling microbial contamination during hydrolysis of AFEX-pretreated corn stover and switchgrass: effects on hydrolysate composition, microbial response and fermentation

“…Xylose utilization also occurred only when glucose was completely exhausted, indicating that xylose utilization is hindered by the presence of glucose, which could occur through a block in transport or other regulatory mechanisms. Consistent with the former, in Z. mobilis, glucose facilitated diffusion protein (Glf) is a shared transporter for both xylose and glucose, but has lower affinity for xylose [ 52 ]. A similar transporter exists in S. cerevisiae [ 53 ].…”

“…A similar transporter exists in S. cerevisiae [ 53 ]. During co-fermentation of mixed sugars, low levels of xylose utilization could be attributed either to competitive interference with glucose for the transporters or slower metabolism of xylose within the organism [ 52 , 53 ]. In addition to the delay, there was also incomplete xylose utilization with only 2/3 of the sugar consumed after 48 h of fermentation (Fig.…”

Genome comparison of different Zymomonas mobilis strains provides insights on conservation of the evolution

“…Recently, different genetic techniques were used to improve the industrial biotechnology capacity of Z . mobilis [ 10 , 11 ]. Genome sequencing analysis of Z .…”

“…The first genome sequence of the Z . mobilis ZM4 was published in 2005[ 10 ]. This strain is regarded as a model organism in Z .…”

Avaliação da expressão de genes da via de Weimberg sobre o catabolismo de xilose na linhagem produtora de PHA_MCL<i>Pseudomonas sp.</i> LFM046.

“…xilose como fonte de carbono. Porém, uma abordagem biotecnológica conhecida como engenharia metabólica somada às análises de genomas, foi utilizada para melhorar o consumo de xilose em leveduras (Peng et al, 2015;Qi et al, 2015;Zhang et al, 2016), bactérias (Dunn, Rao 2015;Mohagheghi et al, 2015;Waltman et al, 2014), e capacitar microrganismos que naturalmente não possuíam a maquinaria metabólica para utilizar esta pentose (Ledesma-Amaro et al, 2016;Lee et al, 2016;Meijnen et al, 2009;van Rensburg et al, 2014;Sekar et al, 2016;Wei et al, 2016). (Nielsen 2001).…”