Optimization of fermentation conditions for production of exopolysaccharide by Bacillus polymyxa

Production of exopolysaccharide (EPS) from a strain of Bacillus polymyxa was studied. Sucrose and potassium nitrate were found to be efficient carbon and nitrogen sources, respectively, for the production of the EPS. EPS production increased with the increase of sucrose concentration, probably due to the facilitated carbon uptake. Optimal pH was 7–8, and a sufficient supply of oxygen was needed for the EPS production. It was noted that the EPS synthesis by this B. polymyxa was growth-associated, indicating that a sufficient supply of nutrients was required for a high production of the EPS. As high as 54?g/l of EPS with a yield of 63% (g EPS/g sucrose) was obtained in 48?h of fed-batch cultivation with intermittent feeding of sucrose and potassium nitrate.     

Influence of culture conditions on exopolysaccharide production by Lactobacillus rhamnosus strain C83

The influence of culture conditions on growth and exopolysaccharide (EPS) production by Lactobacillus rhamnosus strain C83 was investigated using fermentor batch cultures. A temperature shift (from 37 to 25 °C) at the beginning of the exponential growth phase (0–5 h) enhanced EPS production. Furthermore, an optimal environmental pH of 6·2–7·2 improved the performance of strain C83 and partially anaerobic culture conditions (pO₂ from 0 to 10%) triggered EPS over-production by the cells. The sugar composition of this polymer was independent of culture conditions, such as carbon source, medium composition, temperature, pH, pO₂ and growth phases. In all cases, galactose and glucose were the principal components.     

Production of exopolysaccharide by a new mutant strain ofAchromobacter delicatulus using whey fermentation

A novel mutant strain ofAchromobacter delicatulus was cultivated in a 75-L fermentor, using whey as carbon source and production of exocellular glucan was measured. The fermentation had a biphasic character: growth was followed by the phase of polysaccharide production, the maximum of which was 17 g/L.     

Optimization of cellulase-free xylanase production by a novel yeast strain

Summary A novel yeast strain, NCIM 3574, isolated from a decaying wood produced up to 570 IU ml^–1 of xylanolytic enzymes when grown on medium containing 4% xylan. The yeast strain also produced xylanase activity (40–50 IU ml^–1) in the presence of soluble carbon sources like xylose or arabinose. No xylanase activity was detected when the organism was grown on glucose. The crude xylanase preparation showed no activity towards cellulolytic substrates but low levels of -xylosidase (0.1 IU ml^–1) and -l-arabinofuranosidase (0.05 IU ml^–1) were detected. The temperature and pH optima for the crude xylanase preparation were 55°C and 4.5 respectively. The crude xylanase produced mainly xylose from xylan within 5 min. Prolonged hydrolysis of xylan produced xylobiose and arabinose, in addition to xylose, as the end products. The presence of arabinose as one of the end products in xylan hydrolysate could be due to the low levels of arabinofuranosidase enzyme present in the crude fermentation broth.     

Mechanism of adenosine production by xanthine-requiring mutants derived from a Bacillus strain

The xanthine-requiring mutants defective in adenine deaminase (adenase) derived from a Bacillus strain accumulate much adenosine. The mechanism of adenosine production was investigated. Limitation of the guanine-related substances in the fermentation medium facilitated the adenosine accumulation, but the excess of those suppressed it.Metabolic regulation of the purine nucleotide biosynthesis was supposed to be released from both feedback inhibition and repression by limiting the concentration of guanine-related substances in the cells caused by xanthine-requirement. Deficiency in the deaminase activities of adenine, adenosine and AMP and the weak adenosine phosphorylase activity contributed to adenosine accumulation. No apparent changes were observed in the adenylosuccinate synthetase activity and the dephosphorylation activity of AMP compared with the wild strain.     

Chitobiose production by using a novel thermostable chitinase from Bacillus licheniformis strain JS isolated from a mushroom bed

The thermophilic Bacillus licheniformis strain JS was isolated from a bed of mushrooms, Pleurotus sajor-caju. The organism could produce a novel, single-component, thermostable chitinase that was purified by ion-exchange chromatography using DEAE-cellulose in 7.64% yield and in an 8.1-fold enhancement in purity. Its molecular weight is 22 kDa. The enzyme is a chitobiosidase, since the chitin hydrolysate is N^I,N^II-diacetylchitobiose. The optimum temperature for enzyme activity is 55 °C, and the optimum pH is 8.0. It was completely inhibited by Hg²⁺ ions whereas Co²⁺ ions served as an activator. The thermostability of this enzyme is important in the bioconversion of chitinous waste and for the production of chitooligosaccharides.     

Optimization of a culture medium for xylanase production by Bacillus sp. using statistical experimental designs

The concentrations of oat spelt xylan, casein hydrolysate and NH4Cl in the culture medium for production of xylanase from Bacillus sp. I-1018 were optimized by means of response surface methods. The path of steepest ascent was used to approach the optimal region of the medium composition. The optimum composition of the nutrient medium was then easily determined by using a central composite design and was found to be 3.16g/l of xylan, 1.94g/l casein hydrolysate, 0.8g/l of NH4Cl. The xylanase production was increased by 135% when the strain was grown in the optimized medium compared to initial medium.     

Optimization of a culture medium for xylanase production by Bacillus sp. using statistical experimental designs

The concentrations of oat spelt xylan, casein hydrolysate and NH4Cl in the culture medium for production of xylanase from Bacillus sp. I-1018 were optimized by means of response surface methods. The path of steepest ascent was used to approach the optimal region of the medium composition. The optimum composition of the nutrient medium was then easily determined by using a central composite design and was found to be 3.16g/l of xylan, 1.94g/l casein hydrolysate, 0.8g/l of NH4Cl. The xylanase production was increased by 135% when the strain was grown in the optimized medium compared to initial medium.     

Optimization of exopolysaccharide production by probiotic yeast Lipomyces starkeyi VIT-MN03 using response surface methodology and its applications

In the present study, the cultural conditions for exopolysaccharide (EPS) production from probiotic yeast Lipomyces starkeyi VIT-MN03 were optimized using response surface methodology (RSM) to maximize the yield of EPS. Interactions among the various factors viz. sucrose concentration (1–3 g%), NaCl concentration (2–4 g%), pH (3–5), temperature (20–30 °C), and incubation period (20–40 days) during EPS production were studied using Box-Behnken design (BBD). The EPS was purified and characterized using various instrumental analyses. The properties like adhesion, antioxidant, biosurfactant, cholesterol removal, and binding ability to mutagens were also tested for EPS produced. Sixfold increase in EPS production (4.87 g L−1) by L. starkeyi VIT-MN03 was noted under optimized condition. EPS showed a high viscosity (1.8 Pa S−1) and good shear-thinning properties. Instrumental analysis showed that EPS was heteropolysaccharide composed of glucan, mannan, and rhamnan. Lipomyces starkeyi VIT-MN03 exhibited good self-adhesion (95%) and co-aggregation ability (93%). Adhesion efficiency for yeast inoculum containing 5.5 × 107 CFU mL−1 per 9.2 cm2 of Caco-2 cell (colorectal adenocarcinoma) was noted. The probiotic EPS displayed strong antioxidant ability to scavenge hydroxyl radical and DPPH by 58% and 71% respectively. In addition, biosurfactant activity (86%) and cholesterol removal (90%) ability of probiotic EPS was also tested. EPS bound cells of L. starkeyi VIT-MN03 showed good binding ability to mutagens. These results support the effectiveness of using RSM for maximum EPS production. To the best of our knowledge, this is the first report on optimization of EPS production by probiotic yeast.     

Effect of 2-ketogluconic acid synthesis on the exopolysaccharide production in a Rhizobium meliloti strain]

Two categories of carbon substrates are defined for Rhizobium meliloti: the first favours the synthesis of exopolysaccharides (fructose belongs to this category) while the other is not suitable (glucose belongs to this category). With fructose, resting cells synthesize polysaccharides during more than 100 h and this synthesis is at its best in aerobic conditions at 30 degrees C. With glucose, 2-ketogluconic acid accumulates and rapidly stops the synthesis. The method used to stop this acidification allows with glucose a synthesis which can be compared to the one obtained with fructose.     

Optimization of media composition for Nattokinase production by Bacillus subtilis using response surface methodology

Response surface methodology and central composite rotary design (CCRD) was employed to optimize a fermentation medium for the production of Nattokinase by Bacillus subtilis at pH 7.5. The four variables involved in this study were Glucose, Peptone, CaCl(2), and MgSO(4). The statistical analysis of the results showed that, in the range studied; only peptone had a significant effect on Nattokinase production. The optimized medium containing (%) Glucose: 1, Peptone: 5.5, MgSO(4): 0.2 and CaCl(2): 0.5 resulted in 2-fold increased level of Nattokinase (3194.25U/ml) production compared to initial level (1599.09U/ml) after 10h of fermentation. Nattokinase production was checked with fibrinolytic activity.     

Optimization of xylanase production using inexpensive agro-residues by alkalophilic Bacillus subtilis ASH in solid-state fermentation

Alkalophilic Bacillus subtilis ASH produced high levels of xylanase using easily available inexpensive agricultural waste residues such as wheat bran, wheat straw, rice husk, sawdust, gram bran, groundnut and maize bran in solid-state fermentation (SSF). Among these, wheat bran was found to be best substrate. Xylanase production was highest after 72 h of incubation at 37 °C and at a substrate to moisture ratio of 1:2 (w/v). The inoculum level of 15% resulted in maximum production of xylanase. The enzyme production was stimulated by the addition of nutrients such as yeast extract, peptone and beef extract. In contrast, addition of glucose and xylose repressed the production of xylanase. The extent of repression by glucose (10%, w/v) was 81% and it was concentration-dependent. Supplementation of the medium with 4% xylose caused 59% repression. Under optimized conditions, xylanase production in SSF (8,964 U of xylanase/g dry wheat bran) was about twofold greater than in submerged fermentation. Thus, B. subtilis produced a very high level of xylanase in SSF using inexpensive agro-residues, a level which is much higher than that reported by any other bacterial isolate. Furthermore, the enzyme was produced at room temperature and with tap water without the addition of any mineral salt in SSF, leading to a marked decrease in the cost of xylanase production, which enhances its industrial potential.     

离子及表面活性剂对蜡状芽孢杆菌S1发酵的影响

APS是一种由新近分离的蜡状芽孢杆菌（Bacillus cereus）菌株S1分泌产生的新型抗真菌环状多肽。研究了不同的离子对菌株S1发酵生产APS的影响，结果表明，阳离子如K^ ,Na^ ,Al^3 对S1产素APS的产生有促进作用，而Ca^2 ,Fe^2 ,Mg^2 表现出抑制作用，有离子中H2PO4^-,HPO^2-4，对产素的产生具有较强的抑制作用，其它阴离子表现出中性作用，在S1发酵的过程，加入浓度为0．2％－0．8％Tween20和10－100u/mL的青霉素G能够增加APS的效价。     

Optimization of some parameters of solid state fermentation of wheat bran for protease production by a local strain of Rhizopus oryzae

Some parameters of the production of an alkaline protease by Rhizopus oryzae in the solid state fermentation of wheat bran were optimized. Using the optimum parameters of an inoculum age of 7 days, an incubation time of 9 days, an amount of CZAPEK ‐DOX (liquid medium) of 6 ml/g bran and an incubation temperature of 33°C, an activity of 50 U/g bran was achieved. The initial pH of the CZAPEK ‐DOX medium had little effect. Re‐incubation of mouldy bran with only fresh CZAPEK ‐DOX yielded 3 times total activity compared to single‐cycle fermentation. As for the effect of the amount CZAPEK ‐DOX medium, the water constituent contributed more to activity increase than did the salt component. The ARRHENIUS activation energies were 23 and 7.9 kcal/mole below and above the optimum of 33°C, respectively. In all the studies, along with protease production, variation of protein content and specific activity were also observed. Attempts were made to explain the effects and also gauge their implications for large‐scale production.     

枯草芽孢杆菌B47菌株高产抗菌物质的培养基及发酵条件优化

枯草芽孢杆菌Bacillus subtilis B47菌株为番茄内生细菌, 也是玉米小斑病拮抗菌, 能产生对玉米小斑病菌有强烈抑制作用的抗菌物质。以B47菌株发酵液的无菌滤液对玉米小斑病菌的抗菌活性为检测指标, 测定B47菌株产抗菌物质培养所需的最佳碳、氮源和无机盐, 并通过正交试验法对该菌株产抗菌物质的培养基配方和摇瓶发酵条件进行优化。研究结果表明, B47菌株产抗菌物质最佳碳、氮源和无机盐分别为蔗糖、酵母浸膏和MgSO4·7H2O, 最优培养基是YSB (Yeast extract-sucrose-beef extract)培养基, 其配方为: 蔗糖2%, 酵母浸膏2%, 牛肉浸膏1.5%, MgSO4?7H2O 0.06%, FeSO4·7H2O 0.000 9%, 最优发酵条件组合为: 30 °C, pH 7.0, 170 r/min摇床培养6 d, 接种量为1%, 装液量为40 mL/200 mL。     

Comparison of lipopeptide biosurfactants production by Bacillus subtilis strains in submerged and solid state fermentation systems using a cheap carbon source: Some industrial applications of biosurfactants

Biosurfactants, in general has the potential to aid in the recovery of subsurface organic contaminants (environmental remediation) or crude oils (oil recovery). However, high production and purification costs limit its use in these high-volume applications. In the present study, the efficiency of two Bacillus subtilis strains viz., DM-03 and DM-04 for the production of biosurfactants in two fermentation systems viz., solid state fermentation (SSF) and submerged fermentation (SmF) was compared. Both the B. subtilis strains produced appreciable and equal amount of crude lipopeptide biosurfactants (B. subtilis DM-03: 80.0 ± 9 mg/gds in SmF and 67.0 ± 6 mg/gds in SSF; B. subtilis DM-04: 23.0 ± 5.0 mg/gds in SmF and 20.0 ± 2.5 mg/gds in SSF) in the two different fermentation systems using potato peels as cheap carbon source. These thermostable lipopeptide biosurfactants produced by B. subtilis strains either in SSF or in SmF, exhibited strong emulsifying property and could release appreciable amount of oil from saturated sand pack column. Further, it was shown by biochemical analysis, RP-HPLC profile and IR spectra that there is no qualitative and qualitative differences in the composition of crude biosurfactants produced either in SmF or in SSF system.     

一株地衣芽胞杆菌产碱性蛋白酶条件优化

【背景】碱性蛋白酶是众多芽胞杆菌的发酵产物,是工业上极其重要的一类酶。【目的】利用酪素培养基从环境样品中筛选出一株产碱性蛋白酶的菌株,对传代次数、发酵的碳源、氮源、金属离子、磷酸盐、初始pH、接种量和温度进行优化,提高其产碱性蛋白酶的能力并降低发酵成本。【方法】采用革兰氏染色法、扫描电镜、生理生化试验、16S rRNA基因序列对分离的菌株进行鉴定;采用单因素、Plackett-Burman、最陡爬坡和响应面试验优化碱性蛋白酶的发酵条件,使用Minitab对试验数据进行分析。【结果】经鉴定分离菌株为地衣芽胞杆菌,命名为Bacillus licheniformis NWMCC0046。优化后的发酵培养基组成为（g/L）:豆粕50.00,葡萄糖10.00,酵母浸膏13.46,CaCl₂ 0.50,Na₂HPO₄·12H₂O 4.00,KH₂PO₄ 0.30;优化后的培养条件为:pH 7.5,34.81℃,接种量4.13%。在此条件下,摇瓶发酵48 h时碱性蛋白酶...     

Optimization of exopolysaccharide welan gum production by Alcaligenes sp. CGMCC2428 with Tween-40 using response surface methodology

The effect of additives on welan gum production produced by fermentation with Alcaligenes sp. CGMCC2428 was studied. Tween-40 was the best additive for improving welan gum production and welan gum displayed better rheological properties than that obtained by control fermentation without additives. Response surface methodology was employed to optimize the culture conditions for welan gum production in the shake flask culture, including Tween-40 concentration, pH and culture temperature. The optimal conditions were determined as follows: Tween-40 concentration 0.94 g/l, pH 6.9 and temperature 29.6 °C. The corresponding experimental concentration of welan gum was 23.62 ± 0.60 g/l, which was agreed closely with the predicted value (23.48 g/l). Validation experiments were also carried out to prove the adequacy and the accuracy of the model obtained. The welan gum fermentation in a 7.5 l bioreactor reached 24.90 ± 0.68 g/l.     

Effects of macromolecular growth substrates on production of extracellular enzymes by Bacillus species in continuous culture

Bacillus species 11089 and alkalophilic Bacillus species 11203 were both capable of growth in continuous culture on macromolecular substrates, starch, soybean flour, casein, pectin, polypectate, polygalacturonate and carboxymethylcellulose (CMC) when these were used as the carbon-energy source in a mineral salts basal medium. High maximum specific growth rate (micronmax) and biomass values occurred when cells were grown on starch, soybean flour and casein, and low values on pectin, polypectate, polygalacturonic acid and CMC. Hydrolytic enzymes (protease, amylase, polygalacturonate lyase and alkaline phosphatase) were subject to regulation (induction and/or repression) depending on the nature of the growth substrate utilized. In general, high levels of enzymes were produced on soybean flour, casein and starch but low levels on CMC, pectin, polypectate and polygalacturonate.     

Production of biosurfactant at mesophilic and thermophilic conditions by a strain of Bacillus subtilis

The ability of a Bacillus subtilis strain to grow and produce biosurfactant on different carbon and nitrogen sources under thermophilic conditions (45°C) was studied. The strain was able to reduce surface tension to 34 dynes cm⁻¹ on 2% sucrose, and 32 dynes cm⁻¹ on starch after 96 h of growth. The biosurfactant was stable at 100°C and within a wide pH range (3.0–11.0). Biosurfactant formation at mesophilic conditions (30°C) was also studied. The organism was able to produce the maximum amount of biosurfactant when nitrate ions were supplied as the nitrogen source. The potential application of the biosurfactant in oil recovery from desert oil fields, acidic and alkaline environments is demonstrated. The biosurfactant was identical to surfactin as confirmed by TLC and IR analysis. Received 29 May 1997/ Accepted in revised form 03 October 1997