Effect of corn steep liquor on xanthan production by Xanthomonas campestris

Summary The addition of corn steep liquor (CSL) to batch cultures of Xanthomonas campestris using sucrose as carbon source stimulated cell growth rate, viscosity and xanthan production as compared to non-supplemented cultures. The addition of CSL to a basal medium at a dose of 1 g/l, increased xanthan production and viscosity by 22% and 44% respectively. CSL also shortened the cultivation time and promoted a more efficient sucrose utilization for polymer synthesis. After 72 h of incubation the xanthan yield per sucrose consumed in the CSL-amended culture was 0.63 g/g, this is, 15% higher than without CSL addition. At higher doses of CSL cell growth rate was also increased but not polymer production.     

Acetate production byClostridium thermoaceticum in corn steep liquor media

A low-cost nutrient medium based on corn steep liquor (CSL) was developed for the production of acetates byClostridium thermoaceticum. Pre-treatment of CSL with dolime and vitamin supplementation increased the rate of acetate production. Adding excess nutrients in a fed-batch mode minimized by-product formation and increased final acetate concentration from 19 g L^–1 to 40 g L^–1 acetic acid. High yields of acetic acid (0.95 g g^–1 glucose in fed-batch mode) was probably due to the conversion of the lactic acid in CSL into acetic acid by the organism.     

Corn steep liquor as a nutritional source for biocementation and its impact on concrete structural properties

Microbial-induced carbonate precipitation (MICP) has a potential to improve the durability properties and remediate cracks in concrete. In the present study, the main emphasis is placed upon replacing the expensive laboratory nutrient broth (NB) with corn steep liquor (CSL), an industrial by-product, as an alternate nutrient medium during biocementation. The influence of organic nutrients (carbon and nitrogen content) of CSL and NB on the chemical and structural properties of concrete structures is studied. It has been observed that cement-setting properties were unaffected by CSL organic content, while NB medium influenced it. Carbon and nitrogen content in concrete structures was significantly lower in CSL-treated specimens than in NB-treated specimens. Decreased permeability and increased compressive strength were reported when NB is replaced with CSL in bacteria-treated specimens. The present study results suggest that CSL can be used as a replacement growth medium for MICP technology at commercial scale.     

Production and separation of dipeptidyl peptidase IV from Lactococcus lactis: scale up for industrial production

Lactococcus lactis spp. lactis and Lactococcus lactis spp. cremoris are widely used in the manufacture of fermented milk. These strains were compared for production of Dipeptidyl Peptidase IV (DPP IV) enzyme in terms of enzyme activity, specific growth rates and productivity. Lactococcus lactis spp. lactis was produced in 3?L bioreactor and scaled up to 30 and 150?L stirred tank bioreactors, and the enzyme activities were found as 110, 110 and 122?mU?mL(-1), respectively. After 8?h of production, separation steps were performed. While purification fold was 127 and yield was 2.69?%, the molecular weight of the enzyme was estimated as 68?kDa. Partially purified enzyme was enteric coated with capsules and a 95.5?% of DPP IV enzyme passed into the artificial intestine. Results show that production of DPP IV enzyme by Lactococcus lactis spp. lactis strain in submerged culture is comparable with the productions by commercial strains, mostly Aspergillus, in solid state fermentations based on productivity.     

Bacterial and fungal diversity in the starter production process of Fen liquor, a traditional Chinese liquor

Fermented foods and beverages are important parts of human diet. Fen liquor, a Chinese liquor is a fermented beverage that uses a traditional fermentation process. Starters are the main microbial source and also provide nutrients for microorganisms during fermentation. In this study, starters of Fen liquor were produced through a complex traditional fermentation process. To investigate the community structure and the composition of microorganisms in the starter production process, bacterial 16S rRNA and fungal internal transcribed spacer (ITS) regions were sequenced using clone libraries and pyrosequencing, respectively. There was much higher diversity among the bacteria than among the fungi in the starter production process. Bacteria on the surface of the starters belonged mostly to the Lactobacillaceae family, while members of the Bacillacae family were dominant in the interior of the samples that lacked access to air and water. In the fungi population, diversity was high only in the raw material. In all other samples, nearly all of the fungal sequences were from Pichia kudriavzevii, a member of the Saccharomycetaceae family. Nearly all samples showed similar fungal community structures, indicating that there was little change in the fungal community. To the best of our knowledge, this is the first report to reveal the whole process of the starter production of Chinese traditional liquor. The findings obtained in this study provide new insights into understanding the composition of the microbial community during the traditional Chinese liquor starter production process and information about the production process control and monitoring.     

采用玉米秸秆水解糖和玉米浆发酵生产丁二酸

研究了以玉米秸秆水解糖为碳源,不同氮源条件下琥珀酸放线杆菌Actinobacillus succinogenesSF-9的丁二酸发酵产酸能力。结果表明玉米浆可以替代酵母膏作为丁二酸发酵的廉价氮源。厌氧摇瓶丁二酸发酵单因素试验,得到在初糖浓度50 g/L时,玉米浆的较佳用量为20 g/L。在5 L搅拌罐上,考察了不同初始玉米秸秆水解糖浓度对A.succinogenes SF-9发酵生产丁二酸的影响,结果显示高初始秸秆糖浓度对琥珀酸放线杆菌的生长有抑制作用。采用补料分批发酵,发酵60 h丁二酸的产量达到42.7g/L,丁二酸产率82.7%,生产强度0.81 g/(L·h)。丁二酸的产量和生产强度较分批发酵有明显提高。     

Effects of corn steep liquor on production of 2,3-butanediol and acetoin by Bacillus subtilis

The initial concentration of corn steep liquor (CSL) have remarkable effects on not only 2,3-butanediol (2,3-BD) and acetoin (metabolic precursor) production, but also on the ratio of 2,3-BD to acetoin. When a high concentration of CSL was supplemented, cell growth was improved, acetoin reductase (ACR) was stimulated, the concentration of 2,3-BD increased by 78.6%, acetoin decreased by 61.9%, and the ratio of 2,3-BD to acetoin increased by 3.69-fold. The acr gene, encoding ACR, was over-expressed in Bacillus subtilis. Compared to the control (parent strain), low levels of CSL in the engineered strain increased 2,3-BD concentration and the ratio 2,3-BD to acetoin by 13.9% and 39.5%, respectively, and decreased acetoin titer by 18.3%. Acetoin became a major product under low levels of CSL. Also, a knockout strain carrying an acr::cat insertion mutation was constructed. As expected, the loss of ACR activity led to an accumulation of acetoin in the supernatants of acr:: cat mutant cultures. Additionally, the productivity of acetoin was improved by high concentration of CSL. The results above demonstrate the feasibility of using B. subtilis for the production of not only 2,3-BD but also acetoin as a major product.     

Fermentative production of succinic acid from glucose and corn steep liquor byAnaerobiospirillum succiniciproducens

Anaerobiospirillum succiniciproducens requires expensive complex nitrogen sources such as yeast extract and polypeptone for its growth and succinic acid production. It was found thatA. succiniciproducens was able to grow in a minimal medium containing glucose when supplemented with corn steep liquor (CSL) as the sole complex nitrogen source. The concentration of CSL had a significant effect on the glucose consumption byA. succiniciproducens. When 10–15 g/L of CSL was supplemented, cells were grown to an OD₆₆₀ of 3.5 and produced 17.8 g/L succinic acid with 20 g/L glucose. These results are similar to those obtained by supplementing yeast extract and polypeptone, thereby suggesting that succinic acid can be produced more economically using glucose and CSL.     

Anaerobic fermentative production of lactic acid using cheese whey and corn steep liquor

Cheese whey was the most suitable substrate for production of lactic acid under anaerobic conditions by Entercoccus flavescens which, on supplementating with corn steep liquor (5% v/v) and 10 mM CaCO₃ at pH 5.5, 37°C, yielded 12.6 g lactic acid/l in 36 h. Production was scaled up to a 10 l bioreactor under controlled pH and continuous CO₂ supply and gave 28 g lactic acid/l in 30 h resulting in a net 8.7-fold increase in production as compared to unoptimized conditions.     

Cost-effective optimization of gellan gum production by Sphingomonas paucimobilis using corn steep liquor

Abstract

Gellan gum, produced by Sphingomonas paucimobilis, is increasingly used in food and pharmaceutical industries as stabilizing, emulsifying, texturing and gelling agents. However, its high production costs may limit its full commercial potential. Therefore, in this study, we investigated ways to reduce gellan gum production costs and improve yields. We first revealed corn steep liquor (CSL) as a cost-effective nutrient source that can improve gellan gum yields. We then systematically optimized culture conditions even further, and revealed that the addition of Triton X-100 surfactant and selected inorganic nitrogen sources improved gellan gum production. Under our optimized conditions (glucose 33.75?g/L, CSL 10?g/L, urea 2.5?g/L, MgSO₄ 1.08?g/L, KH₂PO₄ 3.24?g/L, K₂SO₄ 1?g/L and Triton X-100 0.75?g/L), we yielded a maximum concentration of 14.41?g/L, which was about 1.5-fold higher than non-optimized CSL-based medium. Our findings highlight the use of CSL as a cost effective and promising nutrient source for industrial production of gellan gum.     

Effects of pH and corn steep liquor variability on mannitol production by Lactobacillus intermedius NRRL B-3693

Lactobacillus intermedius NRRL B-3693 produced mannitol, lactic acid, and acetic acid when grown on fructose at 37°C. The optimal pH for mannitol production from fructose by the heterofermentative lactic acid bacterium (LAB) in pH-controlled fermentation was at pH 5.0. It produced 160.7 ± 1.1 g mannitol in 40 h with a volumetric productivity of 4.0 g l⁻¹ h⁻¹ in a simplified medium containing 250 g fructose, 50 g corn steep liquor (CSL), and 33 mg MnSO₄ per liter. However, the mannitol production by the LAB was severely affected by the variability of CSL. The supplementation of CSL with soy peptone (5 g/l), tryptophan (50 mg/l), tryptophan (50 mg/l) plus tyrosine (50 mg/l), or commercial protease preparation (2 ml/100 g of CSL) enhanced the performance of the inferior CSL and thus helped to overcome the nutrient limitations.     

Improvement of glycerol production by Candida krusei in batch and continuous cultures using corn steep liquor

No fermentation parameter was affected at phosphate concentration above 0.4 g l^–1 when KH₂PO₄ was used as phosphate source and the glucose consumption rate was difficult to control when corn steep liquor (CSL) was adopted as the phosphate source. However, if CSL was supplemented as a source of growth factors instead of as the phosphate source, not only glucose uptake and glycerol was improved, but also fermentation became easy to control and a steady state of continuous culture was easily obtained.     

Brewer's spent grain and corn steep liquor as substrates for cellulolytic enzymes production by Streptomyces malaysiensis

Aims:  To evaluate cellulase production by Streptomyces malaysiensis in submerged fermentation using brewer's spent grain (BSG) and wheat bran (WB) as carbon source, and corn steep liquor (CSL) as nitrogen source, as compared to yeast extract (YE), and partial characterization of the crude enzyme.
Methods and Results:  Maximum cellulase production by Streptomyces malaysiensis (720 U l⁻¹) occurred within 4 days incubation when using a growth medium containing BSG 0·5% (w/v) and CSL1·2% (w/v). CMCases activity showed to be stable over an acidic pH range (2·0–7·0) and in temperatures of 40–60°C. Zymogram indicated three bands of CMCase activity, with different molecular masses.
Conclusion:  S. malaysiensis was able to grow and produce good levels of CMCases using solely brewer's spent grain and corn steep liquor as low-cost substrates, making this strain and these low cost by-product worthy for further investigation, and potentially feasible for biotechnological applications in different areas.
Significance and Impact of the Study:  To our knowledge, this is the first study reporting the use of the low-cost by-products brewer's spent grain and corn steep liquor, as sole substrates for microbial enzyme production.     

High-level production of heterologous proteins using untreated cane molasses and corn steep liquor in Escherichia coli medium

To develop an economical industrial medium, untreated cane molasses (UCM) was tested as a carbon source for fermentation culturing of Escherichia coli. To test the industrial application of this medium, we chose a strain co-expressing a carbonyl reductase (PsCR) and a glucose dehydrogenase (BmGDH). Although corn steep liquor (CSL) could be used as an inexpensive nitrogen source to replace peptone, yeast extract could not be replaced in E. coli media. In a volume of 40 ml per 1-l flask, a cell concentration of optical density (OD₆₀₀) 15.1 and enzyme activities of 6.51 U/ml PsCR and 3.32 U/ml BmGDH were obtained in an optimized medium containing 25.66 g/l yeast extract, 3.88 g/l UCM, and 7.1% (v/v) CSL. When 3.88 g/l UCM was added to the medium at 6 h in a fed-batch process, the E. coli concentration increased to OD₆₀₀ of 24, and expression of both PsCR and BmGDH were twofold higher than that of a batch process. Recombinant cells from batch or fed-batch cultures were assayed for recombinant enzyme activity by testing the reduction of ethyl 4-chloro-3-oxobutanoate to ethyl (S)-4-chloro-3-hydroxybutanoate (CHBE). Compared to cells from batch cultures, fed-batch cultured cells showed higher recombinant enzyme expression, producing 560 mM CHBE in the organic phase with a molar yield of 92% and an optical purity of the (S)-isomer of >99% enantiomeric excess.     

Utilization of the buffering capacity of corn steep liquor in bacterial cellulose production by Acetobacter xylinum

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC). Using a pH sensor for the accurate control of pH, which is one of the most critical factors for efficient BC production, is difficult especially in a baffled shake-flask and an airlift reactor. The buffering capacity of corn steep liquor (CSL) was estimated by measuring (buffering capacity) values in advance and was used to maintain the pH within the optimal range during the production of BC. When CSL was added to either a shake-flask, a stirred-tank reactor or an airlift reactor, BC production was almost the same as that in cultivations where pH was controlled manually or by a pH sensor.     

The effect of corn steep liquor on the transformation of steroids

Summary As a nutrient in growth medium, corn steep liquor (CSL) may suppress 1-dehydrogenation of hydrocortisone 17-acetate byBacillus lentus, 11-hydroxylation of 6-fluoro-16-methyldeoxycorticosterone 21-acetate (FM-DOCA) byCurvularia lunata, and favor the formation of side-products. By means of step-down multiple regression analysis it was found that part of the variation in degree of steroid transformation in dependence on CSL quality can be explained by variable contents of SO₂, calcium and phosphorus for dehydrogenation and by ash, calcium, proline, and zinc for hydroxylation.     

Pilot-scale process development and scale up for antifungal production

A pilot-scale fermentation was developed for an antifungal compound produced by a filamentous fungus. Replacement of galactose with lactose (20-fold cost savings) and a threefold phosphate reduction (15 to 5 g/L) improved productivity 2.5-fold. Addition of supplements—glycine, cobalt chloride, and trace elements—resulted in a further twofold productivity increase, greater process robustness, and less foaming which reduced antifoam addition tenfold (30 to <3 mL/L). Mid-cycle lactose limitations were addressed by raising initial lactose levels (40 to 120 g/L) resulting in another twofold productivity increase. Overall, peak titers increased tenfold from 45 ± 9 to 448 ± 39 mg/L, and productivities improved from 3 to 25 mg/L day. Despite its high productivity, process scale up was challenged by high broth viscosity (5,000–6,000 cP at 16.8 s⁻¹). Gassed power requirements at the 600 L scale (4.7 kW/1,000 L) exceeded available power at the 15,000 L scale (3.0 kW/1,000 L), and broth transfer to the downstream isolation facility was hindered. Mid-cycle broth dilution with up to five 10 vol% additions of 12 wt% lactose solution or whole medium-reduced viscosity three- to fivefold (1,000–1,500 cP at 16.8 s⁻¹), gassed power within scale-up limits (2.5 kW/1,000 L), and peak titer by up to 45%. The process was scaled up to the 15,000 L working volume based on constant aeration rate (vvm) and peak impeller tip speed, raising superficial velocities at similar shear. This strategy maximized mass transfer rates at target gassed power per unit volume levels, and along with controlled broth viscosity, precluded multiple dilution additions. A final titer of 333 mg/L with one dilution addition was achieved, somewhat lower than expected, likely owing to inhibition from some unmeasured volatile compound (not believed to be carbon dioxide) during an extended period of high back-pressure in the early production phase.