Influence of culture conditions on thermostable lipase production by a thermophilic alkalitolerant strain ofBacillus sp

The effect of different culture conditions on thermostable lipase production byBacillus sp. was studied in shake flasks. A maximum enzyme activity of 67–75 nkat/mL was observed in a medium consisting of 0.5% soybean flour and 0.1% stearyl glycerol esters or natural fats. A lipase activity of about 117 nkat/mL was established when the cultivation was carried out in laboratory fermentor at 20% minimal dissolved oxygen level, the enzyme production being increased 1.5 fold compared to that in a flask culture.     

Influence of tissue culture conditions on apogamy in Dryopteris affinis sp. affinis

The naturally-occurring apogamy of some ferns can be modified by culture conditions and growth regulators. Gametophytes of the apogamic fern Dryopteris affinis sp. affinis L., were cultured on Murashige and Skoog (MS) basal medium. Changes in concentration of MS medium components, sucrose, agar and different pH values were tested. The addition of benzyladenine (4.43 M) and naphthalene acetic acid (0.53 M) enhanced sporophyte proliferation on the gametophytes. After one month in culture, the gametophytes formed callus with a high morphogenic capacity. Culture of calli on medium without growth regulators yielded about 10,000 sporophytes per 1 g fresh weight of callus. This pattern of differentiation slowed with time to a point where only gametophyte regeneration was observed.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - F.W. fresh weight - MS Murashige & Skoog medium - NAA 1-naphthalene acetic acid - SE standard error     

Optimization of culture conditions and medium composition for the production of micrococcin GO5 by Micrococcus sp. GO5

To enhance the production of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5, cultivation conditions and medium composition were optimized. The optimal initial pH and temperature for bacteriocin production were 7.0-9.0 and 37 degrees C, respectively. Micrococcus sp. GO5 displayed the highest micrococcin GO5 activity when grown in modified MRS medium that contained lactose or sucrose, rather than glucose, as a carbon source. The maximum bacteriocin activity was obtained in modified MRS medium containing 0.5% tryptone and 1.0% yeast extract as nitrogen sources instead of the other nitrogen sources present in MRS medium. Bacteriocin production was greatly affected by the concentration of K(2)HPO(4); strain GO5 produced eight-fold more bacteriocin in medium containing 2.0-2.5% K(2)HPO(4) than in medium containing 0.2% K(2)HPO(4). The optimal concentration of MgSO(4).7H(2)O for bacteriocin production was 0.5%. The production of micrococcin GO5 was increased 32-fold in shake flask culture and 16-fold in a bioreactor using the optimized medium (TY medium), compared with culturing in MRS medium.     

Effect of culture conditions on lipase production by Fusarium solani in batch fermentation

Lipase (Glycerol ester hydrolase EC 3.1.1.3.) from a Brazilian strain of Fusarium solani FSI has been investigated. The effect of different carbon sources and trace elements added to basal medium was observed with the aim of improving enzyme production. Lipase specific activity was highest (0.45 U mg(-1)) for sesame oil. When this medium was supplemented with trace elements using olive oil, corn oil and sesame oil the lipase specific activity increased to 0.86, 1.89 and 1.64 U mg(-1), respectively, after 96 h cultivation without any considerable biomass increase. The Km of this lipase using pNPP (p-nitrophenylpalmitate) as substrate, was 1.8 mM with a Vmax of 1.7 micromol min(-1) mg protein(-1). Lipase activity increased in the presence of increasing concentrations of hexane and toluene. In contrast, incubation of this enzyme with water-soluble solvents decreased its activity after 10% concentration (v/v) of the solvent. The lipase activity was stable below 35 degrees C but above this temperature activity losses were observed.     

Influence of culture conditions and medium composition on the production of antibacterial compounds by marine Serratia sp. WPRA3

This study was undertaken to investigate the influence of culture conditions and medium components on production of antibacterial compounds by Serratia sp. WPRA3 (JX020764) which was isolated from marine water of Port Dickson, Malaysia. Biochemical, morphological, and molecular characteristics suggested that the isolate is a new candidate of the Serratia sp. The isolate showed strong antimicrobial activity against fungi, Gram-negative and Gram-positive bacteria. This bacterium exhibited optimum antibacterial compounds production at 28°C, pH 7 and 200 rev/min aeration during 72 h of incubation period. Highest antibacterial activity was obtained when sodium chloride (2%), yeast extract (0.5%), and glucose concentration (0.75%) were used as salt, nitrogen, and carbon sources respectively. Different active fractions were obtained by Thin-Layer Chromatography (TLC) and Flash Column Chromatography (FCC) from ethyl acetate crude extracts namely OCE and RCE in different culture conditions, OCE (pH 5, 200 rev/min) and RCE (pH 7/without aeration). In conclusion, the results suggested different culture conditions have a significant impact on the types of secondary metabolites produced by the bacterium.     

The production of hemicellulose-degrading enzymes byBacillus macerans in anaerobic culture

Summary The cell-associated and exocellular hemicellulolytic polysaccharide depolymerase and glycoside hydrolase activity ofBacillus macerans NCDO 1764 was monitored over a range of anaerobic growth conditions in batch and continuous culture. The enzymes were detectable throughout the complete growth cycle in batch culture reaching and maintaining maximum levels in the stationary phase. In continuous culture enzyme activity was largely independent of growth rate (D=0.025–0.1 h^-1) although the activity was reduced at higher dilution rates (0.125–0.15 h^-1). Although activity was detectable over a wide pH range (pH 5.5–7.5) it was pH dependent, and maximum activities of both the cell-associated and exocellular enzymes were measured in cultures maintained at pH 6.5–7.0±0.1.The principal metabolites formed anaerobically from xylose byB. macerans in batch and continuous culture were acetic acid, formic acid and ethanol which represented 95–99% of the products formed. Smaller amounts of acetone,d,l-lactic acid and succinic acid were formed together with traces of butyric acid (<5 nmol/ml) and isovaleric acid (<25 nmol/ml). The proportions of the metabolites produced varied with growth conditions and were influenced by the pH of the culture and the rate and stage of growth of the microorganism.     

响应面法快速优化曲霉Aspergillus sp.F044产脂肪酶培养条件

运用逐因子试验(Seriatim-Factorial Experiment)、Plackett-Burman、Response Surface Methodology(RSM)和单因子试验(Monofactorial Experiment)分析对产脂肪酶曲霉Aspergillus sp.F044产酶培养条件进行了快速优化。首先运用逐因子试验确定Aspergillus sp.F044产脂肪酶最适碳源和氮源,分别为麦芽糖和牛肉膏。在此基础上,通过Plackett-Burrman设计对影响其产酶相关因素进行评估并筛选出具有显著效应的橄榄油、牛肉膏、硫酸镁三个因素。然后通过实验拟合上述三因素与发酵液脂肪酶活力的一阶线性模型,沿着一阶模型给定的路径进行最速上升试验,在上升最高点处由中心组合试验和向应面分析确定其最优培养基组成;最后通过单因子试验确定最适发酵温度和摇床转速。试验优化的最优培养条件为:麦芽糖1.5%(w/v),硫酸铵7‰(w/v),磷酸氢二钾1‰(w/v),牛肉膏1.25%(w/v),硫酸镁2.11‰(w/v),橄榄油1.41%(v/v),自然pH,250r/min和30℃培养72h酶活达32.15U/mL。与初始11.18U相比,酶活提高2.88倍。     

Influence of culture conditions of Gordonia jacobaea MV-26 on canthaxanthin production.

Commercial interest in the use of natural pigments isolated from microorganisms has increased in recent years; hence, molecules belonging to the polyisoprenoid group (i.e. beta-carotene, astaxanthin, and canthaxanthin) have been the focus of much attention. The bacterium Gordonia jacobaea readily synthesizes and accumulates large amounts of canthaxanthin (beta-beta'-carotene-4,4'-dione), which is widely used in the food and cosmetics industries. In the present work, the effects of different low-cost raw materials on fermentation and canthaxanthin accumulation by a hyperpigmented strain of G. jacobaea were studied. Canthaxanthin production and peak levels of accumulation varied according to the different media used.     

Simul taneous production of alpha and beta amylases byBacillus subtilis MIR-5 in batch and continuous culture

Summary Simultaneous production of - and -amylase was studied in batch and continuous culture using starch as substrate inB. subtilis MIR-5. By mainipulating the cultural condition, both enzymes could then be produced by the same strain.Footnote: dedicated to 75^th aniverssary of Dr. Raul E. Trucco.     

Effect of culture conditions on the production of an extracellular proteinase byThermus sp. Rt41A

Thermus sp. Rt41A produced a single extracellular proteinase, as determined by fast protein liquid chromatography and isoelectric focusing. Proteinase activity was expressed from very early in the log phase, and halted when the growth substrate was exhausted. There was no continued proteinase production in the stationary phase. Proteinase production was not stimulated by O₂ limitation, not repressed by amino acid growth substrates, and its production could not be correlated to the type or oxidation state of the carbon and energy source or the growth rate on different carbon and energy sources. Growth on certain substrates, e.g. glutamate and glucose, resulted in production of high levels of proteinase, whereas others, such as acetate, resulted in low proteinase levels. Acetate repressed proteinase production in cultures growing on L-glutamate. In continuous culture on L-glutamate, acetate or pyruvate, proteinase production was highest at higher growth (dilution) rates. The kinetics of proteinase production in continuous culture on L-glutamate can be interpreted as evidence for the constitutive nature of proteinase expression byThermus sp. Rt41A. The data obtained show that the control of proteinase production is different to that postulated forThermus sp. Ok6.A1.     

Influence of culture conditions on the production of milk-clotting enzyme from Rhizomucor

The ratio of milk-clotting activity to proteolytic activity (MC/PA) was used as an index to determine the quality of milk-clotting enzyme. Solid-state fermentation on wheat bran for 5 days at room temperature gave optimal production for enzyme by Rhizomucor miehei and R. pusillus. A ratio of wheat bran to moisture of 1:0.6 (w/v) gave best results. Adding skim milk powder to the media of R. miehei did not improve the MC/PA ratio but 4% (w/w) of the powder did improve the ratio with R. pusillus. Co-cultivation of R. miehei with R. pusillus did not change the MC/PA ratio.The authors are with the Department of Biotechnogy, Bharathiar University. Coimbatore-641 046 India     

Effect of Penicillium expansum culture conditions on patulin production.

Penicillium expansum strains grown on Capek-Dox liquid medium excreted patulin to the medium. Its amount increased until day 12, then smaller amounts of the toxin were observed. Maximum patulin excretion took place at 25 degrees C, pH 6, although at 5 degrees C, pH 3 the presence of this mycotoxin was also observed. The highest amount of patulin produced was observed in medium containing fructose.     

Rhizopus sp.PW358菌脂肪酶固态发酵生产

研究了Rhizopus sp.PW358菌的固态生长和产脂肪酶条件。结果表明：黄豆饼粉为培养基的基本成分,用来生产脂肪酶。培养基中可加入淀粉和蛋白胨作为碳源和源,有利于脂肪酶的合成,培养基的含水量以及金属离子Ca^2 ,Mg^2 的浓度也影响Rhizopus sp.PW358菌和脂肪酶 产生。在优化条件下,12g豆粉中含1.0g淀粉及0.5g蛋白胨、15ml营养盐中Ca^2 ,Mg^2 离子浓度分别为8．0和4．0g/L,培养基含水量为55．6％,在接种后培养48h,酶活力可达最大值320IU／g干培养基。脂肪酶的基本性质研究表明,酶的最适反应温度和PH分别为35℃和7．0,酶的半失活温度为53．5℃,不同的PH环境中,30℃保温1h后酶在PH6．5－8．5范围内较为稳定。     

Influences of cultural medium component on the production of poly(γ-glutamic acid) byBacillus sp. RKY3

In this study, the cultural medium used for the efficient production of γ-PGA with a newly isolatedBacillus sp. RKY3 was optimized. It was necessary to supplement the culture medium withl-glutamic acid and an additional carbon source in order to induce the effective production of γ-PGA. The amount of γ-PGA increased with the addition ofl-glutamic acid to the medium. The addition of 90 g/Ll-glutamic acid to the medium resulted in the maximal yield of γ-PGA (83.2 g/L). The optimum nitrogen source was determined to be peptone, but corn steep liquor, a cheap nutrient, was also found to be effective for γ-PGA production. Both the γ-PGA production and cell growth increased rapidly with the addition of small amounts of K₂HPO₄ and MgSO₄·7H₂O.Bacillus sp. RKY3 appears to require Mg²⁺, rather than Mn²⁺, for γ-PGA production, which is distinct from the production protocols associated with other, previously reported bacteria.Bacillus sp. RKY3 may also have contributed some minor γ-PGA depolymerase activity, resulting in the reduction of the molecular weight of the produced γ-PGA at the end of fermentation.     

Investigation of lipase production by a new isolate of Aspergillus sp.

Fungi isolated from soil were screened for exogenous lipolytic activity. The highest lipase activity was found in a new soil isolate of Aspergillus sp. Some optimal cultural parameters influencing the growth and production of extracellular lipase from this Aspergillus sp. were investigated. The lipase yield was maximum on day 4 of incubation of the culture at pH 5.5 and 30 °C. When the medium was prepared using olive oil as carbon source and peptone as a nitrogen source, better lipase yields were obtained. Aeration enhanced growth and lipase production.     

Influence of culture conditions on production and freeze-drying tolerance of Paecilomyces fumosoroseus blastospores

With the goal of developing a defined medium for the production of desiccation-tolerant blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus, we evaluated the impact of various media components such as amino acids, carbohydrates, trace metals and vitamins on hyphal growth and sporulation of P. fumosoroseus cultures and on the freeze-drying tolerance of blastospores produced under these conditions. A comparison of 13 amino acids as sole nitrogen sources showed that glutamate, aspartate, glycine and arginine supported biomass accumulations (12–16 mg ml⁻¹) and blastospore yields (6–11 × 10⁸ blastospores ml⁻¹) comparable to our standard production medium which contains casamino acids as the nitrogen source. Using glutamate as the sole nitrogen source, tests with various carbohydrates showed that P. fumosoroseus grew best on glucose (18.8 mg biomass ml⁻¹) but produced similar blastospore concentrations (7.3–11.0 × 10⁸) when grown with glucose, glycerol, fructose or sucrose. P. fumosoroseus cultures grown in media with sodium citrate or galactose as the sole carbohydrate produced lower blastospore concentrations but more-desiccation-tolerant spores. Zinc was the only trace metal tested that was required for optimal growth and sporulation. In a defined medium with glutamate as the nitrogen source, vitamins were unnecessary for P. fumosoroseus growth or sporulation. When blastospores were freeze-dried in the absence of a suspension medium, residual glucose (>2.5% w/v) was required for enhanced spore survival. Thus, a defined medium containing basal salts, glucose, glutamate and zinc can be used to produce optimal concentrations of desiccation-tolerant blastospores of P. fumosoroseus. Received 27 October 1998/ Accepted in revised form 06 May 1999     

Biological denitration of propylene glycol dinitrate byBacillus sp. ATCC 51912

In previous studies, bacterial cultures were isolated that had the ability to degrade the nitrate ester glyceryl trinitrate (i.e. nitroglycerin). The goal of the present study was to examine the ability of resting cells and cell-free extracts of the isolateBacillus sp. ATCC 51912 to degrade the more recalcitrant nitrate ester propylene glycol dinitrate (PGDN). It was observed that the PGDN-denitrating activity was expressed during growth even when cells were cultured in the absence of nitrate esters. This indicates that nitrate esters are not required for expression of denitration activity. Using cell-free extracts, PGDN was observed to be sequentially denitrated to propylene glycol mononitrate (PGMN) and propylene glycol with the second denitration step proceeding more slowly than the first. Also it was observed that dialysis of the cell-free extracts did not affect denitration activity indicating that regenerable cofactors [e.g. NAD(P)H or ATP] are not required for denitration.     

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.     

Optimization of extracellular lipase production by Geotrichum sp. using factorial design

Response surface methodology was employed to study the effects of carbon source (soy oil, olive oil and glucose) and nitrogen source concentrations (corn steep liquor and NH(4)NO(3)) on the lipase production by Geotrichum sp. The experiment included a 2(4) central composite rotatable design (CCRD) and four others 2(3) CCRD. According to the responses from the experimental designs, the effects of each variable were calculated and the interactions between them were determined. The response surface methodology was applied for the optimization of the nutrient concentrations in the culture medium for the enzyme production, at 30 degrees C. The optimum medium composition for lipase production by Geotrichum sp. was ammonium nitrate 2.1-2.5%, corn steep liquor 13-15% and soy oil 0.6% as carbon source, which lead to a lipase activity of about 20 U/ml. Using olive oil as carbon source, the optimum composition was ammonium nitrate 0.8-1%, corn steep liquor 13-15% and olive oil 0.6%, leading to an activity of 17 U/ml.     

Immobilization of Burkholderia sp. lipase on a ferric silica nanocomposite for biodiesel production

In this work, lipase produced from an isolated strain Burkholderia sp. C20 was immobilized on magnetic nanoparticles to catalyze biodiesel synthesis. Core-shell nanoparticles were synthesized by coating Fe(3)O(4) core with silica shell. The nanoparticles treated with dimethyl octadecyl [3-(trimethoxysilyl) propyl] ammonium chloride were used as immobilization supporters. The Burkholderia lipase was then bound to the synthesized nanoparticles for immobilization. The protein binding efficiency on alkyl-functionalized Fe(3)O(4)-SiO(2) was estimated as 97%, while the efficiency was only 76% on non-modified Fe(3)O(4)-SiO(2). Maximum adsorption capacity of lipase on alkyl-functionalized Fe(3)O(4)-SiO(2) was estimated as 29.45 mg g(-1) based on Langmuir isotherm. The hydrolytic kinetics (using olive oil as substrate) of the lipase immobilized on alkyl-grafted Fe(3)O(4)-SiO(2) followed Michaelis-Menten model with a maximum reaction rate and a Michaelis constant of 6251 Ug(-1) and 3.65 mM, respectively. Physical and chemical properties of the nanoparticles and the immobilized lipase were characterized by Brunauer-Emmett-Teller (BET) analysis, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR). Moreover, the immobilized lipase was used to catalyze the transesterification of olive oil with methanol to produce fatty acid methyl esters (FAMEs), attaining a FAMEs conversion of over 90% within 30 h in batch operation when 11 wt% immobilized lipase was employed. The immobilized lipase could be used for ten cycles without significant loss in its transesterification activity.