Exploring islands of stability in the design space of cylindrical shell structures

<p><b>Fed-batch fermentation of glucose by <i>R</i>. <i>ornithinolytica</i> B6 with an agitation speed of 200 rpm;</b> (a) without pH control; (b) with pH maintained at 7.0; (c), pH controlled at 5.5 after pH dropped to 5.5 from the initial pH of 7.0.; ■, glucose; □, growth; ♢, ethanol; ●, acetoin; ○, 2,3-BD; ♦, acetic acid; ▲, succinic acid; △, lactic acid; +, butyric acid.</p

Additional file 1 of High production of ectoine from methane in genetically engineered Methylomicrobium alcaliphilum 20Z by preventing ectoine degradation

Supplementary Material

Metabolite production by <i>K</i>. <i>oxytoca</i> M1 using various glucose concentrations in flask cultures (initial pH 6.5, 30°C, 200 rpm, 48 hours cultivation).

<p>Metabolite production by <i>K</i>. <i>oxytoca</i> M1 using various glucose concentrations in flask cultures (initial pH 6.5, 30°C, 200 rpm, 48 hours cultivation).</p

Comparison of products in fed-batch fermentation by <i>K</i>. <i>oxytoca</i> M1 using different neutralizing agents for pH control at 6.

<p>¹Fed-batch fermentation was carried out in a bioreactor containing 1 L medium containing glucose, yeast extract (5 g/L), and casamino acid (10 g/L), 200 rpm, 30°C for 36 hours.</p><p>Comparison of products in fed-batch fermentation by <i>K</i>. <i>oxytoca</i> M1 using different neutralizing agents for pH control at 6.</p

MOESM1 of High production of 2,3-butanediol from biodiesel-derived crude glycerol by metabolically engineered Klebsiella oxytoca M1

Additional file 1: Figure S1. Schematic representation for generating of deletion mutants using the Îť Red recombination method. Figure S2. PCR verification for the deletion of pduC and ldhA genes from K. oxytoca M1 and K. oxytoca M2, respectively. Figure S3. Relative production of meso-2,3-BDO and (2S, 3S)-2,3-BDO by K. oxytoca M1and K. oxytoca KCTC1686 using glucose or glycerol as the carbon sources. Table S1. Net NADH balance for the corresponding product formation per mole of glycerol

Effect of complex nitrogen source on 2,3-BDO fermentation.

<p>(a) dry cell weight and (b) 2,3-BDO production. <i>K</i>. <i>oxytoca</i> M1 was grown for 12 hours at 30°C and 200 rpm in an Erlenmeyer flask containing 60 g/L glucose. Growth medium used were the defined medium (□) and the defined medium supplemented with 5 g/L yeast extract and 10 g/L casamino acid (i.e. the modified medium) (■).</p

Acetoin reduction activity and 2,3-BDO oxidation activity of <i>K</i>. <i>oxytoca</i> M1 and <i>K</i>. <i>oxytoca</i> (pUC18CM-<i>budC</i>).

<p>Activity was analyzed with the crude protein extract of each strain. Bars indicate acetoin reduction activity (■) and 2,3-BDO oxidation activity (□). One unit of specific activity was defined as 1 μmol NADH consumed or generated per minute per 1 mg crude protein.</p

Time course of 2,3-butanediol production by <i>K</i>. <i>oxytoca</i> M1 at different agitation speeds.

<p>(a) 200 rpm, (b) 300 rpm, and (c) 400 rpm. Symbols indicate dry cell weight (■), residual glucose (□), 2,3-BDO (▲), and acetoin (▼).</p

Comparison of fed-batch fermentation results of <i>K</i>. <i>oxytoca</i> M1 (pUC18CM-<i>budC</i>) with the parent strain at 300 rpm and 400 rpm.

<p>Comparison of fed-batch fermentation results of <i>K</i>. <i>oxytoca</i> M1 (pUC18CM-<i>budC</i>) with the parent strain at 300 rpm and 400 rpm.</p

Enhanced 2,3-Butanediol Production by Optimizing Fermentation Conditions and Engineering <i>Klebsiella oxytoca</i> M1 through Overexpression of Acetoin Reductase

<div><p>Microbial production of 2,3-butanediol (2,3-BDO) has been attracting increasing interest because of its high value and various industrial applications. In this study, high production of 2,3-BDO using a previously isolated bacterium <i>Klebsiella oxytoca</i> M1 was carried out by optimizing fermentation conditions and overexpressing acetoin reductase (AR). Supplying complex nitrogen sources and using NaOH as a neutralizing agent were found to enhance specific production and yield of 2,3-BDO. In fed-batch fermentations, 2,3-BDO production increased with the agitation speed (109.6 g/L at 300 rpm vs. 118.5 g/L at 400 rpm) along with significantly reduced formation of by-product, but the yield at 400 rpm was lower than that at 300 rpm (0.40 g/g vs. 0.34 g/g) due to acetoin accumulation at 400 rpm. Because AR catalyzing both acetoin reduction and 2,3-BDO oxidation in <i>K</i>. <i>oxytoca</i> M1 revealed more than 8-fold higher reduction activity than oxidation activity, the engineered <i>K</i>. <i>oxytoca</i> M1 overexpressing the <i>budC</i> encoding AR was used in fed-batch fermentation. Finally, acetoin accumulation was significantly reduced by 43% and enhancement of 2,3-BDO concentration (142.5 g/L), yield (0.42 g/g) and productivity (1.47 g/L/h) was achieved compared to performance with the parent strain. This is by far the highest titer of 2,3-BDO achieved by <i>K</i>. <i>oxytoca</i> strains. This notable result could be obtained by finding favorable fermentation conditions for 2,3-BDO production as well as by utilizing the distinct characteristic of AR in <i>K</i>. <i>oxytoca</i> M1 revealing the nature of reductase.</p></div