Kinetic studies on a flocculent strain of Zymomonas mobilis

Lee, J. H.; Skotnicki, M. L.; Rogers, Peter L.

doi:10.1007/bf00127795

Cited by 41 publications

(16 citation statements)

References 5 publications

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“…AcR was capable of efficient ethanol production in the presence of 20 g/L sodium acetate, while the parent strain ZM4 was inhibited completely under the same condition (Joachimsthal et al 1998). Strain ZM401 is a flocculating mutant of ZM4 generated by NTG mutagenesis as well (Lee et al 1982). Recent study showed that ZM401 had improved tolerance to inhibitory compounds in the hydrolysate, particularly acetic acid and vanillin, than wild-type strain ZM4, and could be a suitable host for bioethanol production (Zhao et al 2014).…”

Section: +mentioning

confidence: 99%

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

Yang

Tang

et al. 2018

Bioresour. Bioprocess.

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Pretreatment is the key step to overcome the recalcitrance of lignocellulosic biomass making sugars available for subsequent enzymatic hydrolysis and microbial fermentation. During the process of pretreatment and enzymatic hydrolysis as well as fermentation, various toxic compounds may be generated with strong inhibition on cell growth and the metabolic capacity of fermenting strains. Zymomonas mobilis is a natural ethanologenic bacterium with many desirable industrial characteristics, but it can also be severely affected by lignocellulosic hydrolysate inhibitors. In this review, analytical methods to identify and quantify potential inhibitory compounds generated during lignocellulose pretreatment and enzymatic hydrolysis were discussed. The effect of hydrolysate inhibitors on Z. mobilis was also summarized as well as corresponding approaches especially the high-throughput ones for the evaluation. Then the strategies to enhance inhibitor tolerance of Z. mobilis were presented, which include both forward and reverse genetics approaches such as classical and novel mutagenesis approaches, adaptive laboratory evolution, as well as genetic and metabolic engineering. Moreover, this review provided perspectives and guidelines for future developments of robust strains for efficient bioethanol or biochemical production from lignocellulosic materials.

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Section: +mentioning

confidence: 99%

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

Yang

Tang

et al. 2018

Bioresour. Bioprocess.

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“…mobilis is a Gram-negative bacterium which produces ethanol in anaerobic conditions. The productivity of ethanol reaches up to 12% (w/v), varies between strains and depends on conditions of incubation (concentration and types of carbon sources, temperature and pH) [5,6]. Z. mobilis offers several attractive features.…”

Section: Introductionmentioning

confidence: 99%

“…The lack of side products significantly increases the yield and decreases the complexity of downstream processes. Moreover, Z. mobilis characterizes low biomass production (only 2% of the source of carbon is converted into biomass) [6] and a high rate of metabolism of glucose through the Entner-Doudoroff pathway [7]. Furthermore, these bacteria can ferment large variety of substrates and have high tolerance for osmotic stress [6] and concentration of ethanol (up to 16%) [8].…”

Section: Introductionmentioning

confidence: 99%

Droplet Microfluidic Technique for the Study of Fermentation

et al. 2015

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Abstract:We demonstrate a technique that uses microdroplets for culturing and selecting bacterial cultures in a model biotechnological application. We propose an assay for determination of ethanol concentration that provides increased dynamic range and is compatible with droplet microfluidic screening technologies. The assay comprises two enzymes-alcohol oxidase (AOX) and horseradish peroxidase (HRP)-and a colorimetric readout system of phenol-4-sulfonic acid (PSA) and 4-aminoantipyrine (4-AAP). The microdroplet method provides high repeatability (a relative error of measured ethanol concentration < 5%), high specificity for ethanol, low consumption of reagents and wide dynamic range (1-70 g¨L´1) compared to existing assays. We report the use of this method in a screen of ethanol generation efficiency of Zymomonas mobilis (strain 3881) against the concentration of glucose in the culture media.

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“…Flocculation can be advantageous for collecting cells or for immobilizing cells for use in continuous flow bioreactors (7).The genetic factors behind S. cerevisiae flocculation are relatively well understood (8,9) to the extent that flocculation can be genetically manipulated 60 (10). Flocs have also been observed in Z. mobilis and have been studied after enriching for flocforming mutants that arouse spontaneously (11) or after chemical mutagenesis (12). Research on Z. mobilis flocs has thus far primarily focused on their utility in cell-recycle bioreactors (12) and their increased tolerance of inhibitory chemicals found in cellulosic hydrolysates (13).…”

mentioning

confidence: 99%

Cell aggregation and aerobic respiration facilitate survival of Zymomonas mobilis ZM4 in an aerobic minimal medium

Jones-Burrage

Kremer

McKinlay

2019

Preprint

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Zymomonas mobilis produces ethanol from glucose near the theoretical maximum yield, making it a potential alternative to yeast for industrial ethanol production. A potentially useful industrial feature is the ability to form multicellular aggregates called flocs, which can settle 15 quickly and exhibit higher resistance to harmful chemicals. While spontaneous floc-forming Z. mobilis mutants have been described, little is known about the natural conditions that induce Z. mobilis floc formation and the genetic factors involved. Here we found that wild-type Z. mobilis forms flocs in response to aerobic growth conditions but only in a minimal medium. We identified a cellulose synthase gene cluster and a single diguanylate cyclase that are essential 20 for both floc formation and survival in an aerobic minimal medium. We also found that NADH dehydrogenase 2, a key component of the aerobic respiratory chain, is important for survival in an aerobic minimal medium, providing a physiological role for this enzyme which has previously been found to be disadvantageous in aerobic rich media. Supplementation of the minimal medium with vitamins also promoted survival but did not inhibit floc formation. 25

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Kinetic studies on a flocculent strain of Zymomonas mobilis

Cited by 41 publications

References 5 publications

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

Droplet Microfluidic Technique for the Study of Fermentation

Cell aggregation and aerobic respiration facilitate survival of Zymomonas mobilis ZM4 in an aerobic minimal medium

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