红茶菌群中菌株相互作用影响菌体生长和代谢

[背景]红茶菌是一种由细菌和酵母菌共生发酵而成的传统茶饮料.该饮料中含有多种有益人体健康的营养物质,具有促进消化、消炎、抗菌、抗糖尿病等生理作用.这些有益的代谢物是以醋酸菌和酵母菌为主的微生物相互作用而产生的.因此,红茶菌是一个优良的研究微生物相互作用的体系.[目的]分析不同菌株单独培养和混合培养对菌体生长和代谢产物的...     

Characterization of Antimicrobial Activity in Kombucha Fermentation

Fermented tea drink, Kombucha, can inhibit the growth of Shigella sonnei, Escherichia coli, Salmonella enteritidis and Salmonella typhimurium. Several metabolites were analyzed every two days during a 14‐day Kombucha fermentation. Levels of acetic acid and gluconic acid were found to increase with fermentation time. No lactic acid or ethanol was detected. Systematic investigation of the antimicrobial activity in Kombucha revealed the presence of antimicrobial compounds other than organic acids or proteins (enzymes) produced during fermentation or the tannins originally present in the tea broth.     

Continuous gluconic acid production by isolated yeast-like mould strains of <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis>

By extensive microbial screening, about 50 strains with the ability to secrete gluconic acid were isolated from wild flowers. The strains belong to the yeast-like mould Aureobasidium pullulans (de Bary) Arnaud. In shake flask experiments, gluconic acid concentrations between 23 and 140 g/l were produced within 2 days using a mineral medium. In batch experiments, various important fermentation parameters influencing gluconic acid production by A. pullulans isolate 70 (DSM 7085) were identified. Continuous production of gluconic acid with free-growing cells of the isolated yeast-like microorganisms was studied. About 260 g/l gluconic acid at total glucose conversion could be achieved using continuous stirred tank reactors in defined media with residence times (RT) of about 26 h. The highest space-time-yield of 19.3 g l(-1) x h(-1)) with a gluconic acid concentration of 207.5 g/l was achieved with a RT of 10.8 h. The possibility of gluconic acid production with biomass retention by immobilised cells on porous sinter glass is discussed. The new continuous gluconate fermentation process provides significant advantages over traditional discontinuous operation employing Aspergillus niger. The aim of this work was the development of a continuous fermentation process for the production of gluconic acid. Process control becomes easier, offering constant product quality and quantity.     

Solid-state fermentation for gluconic acid production from sugarcane molasses by Aspergillus niger ARNU-4 employing tea waste as the novel solid support

Solid-state fermentation (SSF) was evaluated to produce gluconic acid by metal resistant Aspergillus niger (ARNU-4) strain using tea waste as solid support and with molasses based fermentation medium. Various crucial parameters such as moisture content, temperature, aeration and inoculum size were derived; 70% moisture level, 30 degrees C temperature, 3% inoculum size and an aeration volume of 2.5l min(-1) was suited for maximal (76.3 gl(-1)) gluconic acid production. Non-clarified molasses based fermentation media was utilized by strain ARNU-4 and maximum gluconic acid production was observed following 8-12 days of fermentation cycle. Different concentrations of additives viz. oil cake, soya oil, jaggary, yeast extract, cheese whey and mustard oil were supplemented for further enhancement of the production ability of microorganism. Addition of yeast extract (0.5%) was observed inducive for enhanced (82.2 gl(-1)) gluconic acid production.     

Spores of Aspergillus niger as reservoir of glucose oxidase synthesized during solid-state fermentation and their use as catalyst in gluconic acid production

AIMS: To exploit conidiospores of Aspergillus niger as a vector for glucose oxidase extraction from solid media, and their direct use as biocatalyst in the bioconversion of glucose to gluconic acid. METHODS AND RESULTS: Spores of A. niger (200 h old) were shown to fully retain all the glucose oxidase synthesized by the mycelium during solid-state fermentation (SSF). They acted as catalyst and carried out the bioconversion reaction effectively, provided they were permeabilized by freezing and thawing. Glucose oxidase activity was found retained in the spores even after repeated washings. Average rate of reaction was 1.5 g l(-1) h(-1) with 102 g l(-1) of gluconic acid produced out of 100 g l(-1) glucose consumed after approx. 100 h reaction, which corresponded to a molar yield close to 93%. These results were obtained with permeabilized spores in the presence of a germination inhibitor, sodium azide. CONCLUSIONS: Spores of A. niger served as efficient catalyst in the model bioconversion reaction after permeabilization. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first detailed study on the ability of A. niger spores to act as reservoir of enzyme synthesized during SSF without its release into solid media. Use of this material served as an innovative concept for enzyme extraction and purification from a solid medium. Moreover, this approach could compete efficiently with the conventional use of mycelial form of the fungus in gluconic acid production.     

Improved brewing of millet beer – (OYOKPO) and production of single cell proteins from the spent grain

The improved method for preparing Oyokpo a Nigerian fermented beverage from millet, and the preparation of single cell proteins from the spent grain is described. Improvement of the brew was made by controlled malting, mashing and brewing with a pure culture of Saccharomyces cerevisiae. It had a reducing sugar content of 19.73 g/100 ml before fermentation and after fermentation 5.56% alcohol, 0.58 g/100 ml titratable acidity as acetic acid, a final pH of 4.2 and consisted of a yellowish clear liquid, slightly sour. The native brew had a reducing sugar content of 7.37 g/100 ml before fermentation and after fermentation, 2.40% alcohol, 0.43 g/100 ml titratable acidity, a final pH of 3.8 and consisted of a creamy yellowish liquid with a very sour taste. Fermented spent grain gave a higher protein yield compared to unfermented or ground millet. The lipids, proteins and crude fibre were 4.94%, 11.20% and 4.33% respectively for ground millet, 12,79%, 23.77% and 19.46% respectively for unfermented spent grain and 19.61%, 47.28% and 32.09% respectively for fermented spent grain. The high protein and fibre content of the fermented spent grain points to its potential as a feed supplement for ruminants.     

Bioconversion of grape must into modulated gluconic acid production by Aspergillus niger ORS-4.410

AIMS: Analysis of regulators for modulated gluconic acid production under surface fermentation (SF) condition using grape must as the cheap carbohydrate source, by mutant Aspergillus niger ORS-4.410. Replacement of conventional fermentation condition by solid-state surface fermentation (SSF) for semi-continuous production of gluconic acid by pseudo-immobilization of A. niger ORS-4.410. METHODS AND RESULTS: Grape must after rectification was utilized for gluconic acid production in batch fermentation in SF and SSF processes using mutant strain of A. niger ORS-4.410. Use of rectified grape must led to the improved levels of gluconic acid production (80-85 g l(-1)) in the fermentation medium containing 0.075% (NH4)2HPO4; 0.1% KH2PO4 and 0.015% MgSO4.7H2O at an initial pH 6.6 (+/-0.1) under surface fermentation. Gluconic acid production was modulated by incorporating the 2% soybean oil, 2% starch and 1% H2O2 in fermentation medium at continuously high aeration rate (2.0 l min(-1)). Interestingly, 95.8% yield of gluconic acid was obtained when A. niger ORS-4.410 was pseudo-immobilized on cellulose fibres (bagasse) under SSF. Four consecutive fermentation cycles were achieved with a conversion rate of 0.752-0.804 g g(-1) of substrate into gluconic acid under SSF. CONCLUSIONS: Use of additives modulated the gluconic acid production under SF condition. Semi-continuous production of gluconic acid was achieved with pseudo-immobilized mycelia of A. niger ORS-4.410 having a promising yield (95.8%) under SSF condition. SIGNIFICANCE AND IMPACT OF THE STUDY: The bioconversion of grape must into modulated gluconic acid production under SSF conditions can further be employed in fermentation industries by replacing the conventional carbohydrate sources and expensive, energy consuming fermentation processes.     

Optimisation of fermentation conditions for gluconic acid production by a mutant of Aspergillus niger

Aspergillus niger ORS-4, isolated from the sugarcane industry waste materials was found to produce notable level of gluconic acid. From this strain, a mutant Aspergillus niger ORS-4.410 having remarkable increase in gluconic acid production was isolated and compared for fermentation properties. Among the various substrates used, glucose resulted into maximum production of gluconic acid (78.04 g/L). 12% concentration led to maximum production. Effect of spore age and inoculum level on fermentation indicated an inoculum level of 2% of the 4-7 days old spores were best suited for gluconic acid production. Maximum gluconate production could be achieved after 10-12 days of the fermentation at 30 degrees C and at a pH of 5.5. Kinetic analysis of production indicated that growth of the mutant was favoured during initial stages of the fermentation (4-8 days) and production increased during the subsequent 8-12 days of the fermentation. CaCO3 and varying concentrations of different nutrients affected the production of gluconic acid. Analysis of variance for the factors evaluated the significant difference in the production levels.     

Production of mannitol and lactic acid by fermentation with Lactobacillus intermedius NRRL B-3693

Lactobacillus intermedius B-3693 was selected as a good producer of mannitol from fructose after screening 72 bacterial strains. The bacterium produced mannitol, lactic acid, and acetic acid from fructose in pH-controlled batch fermentation. Typical yields of mannitol, lactic acid, and acetic acid from 250 g/L fructose were 0.70, 0.16, and 0.12 g, respectively per g of fructose. The fermentation time was greatly dependent on fructose concentration but the product yields were not dependent on fructose level. Fed-batch fermentation decreased the time of maximum mannitol production from fructose (300 g/L) from 136 to 92 h. One-third of fructose could be replaced with glucose, maltose, galactose, mannose, raffinose, or starch with glucoamylase (simultaneous saccharification and fermentation), and two-thirds of fructose could be replaced with sucrose. L. intermedius B-3693 did not co-utilize lactose, cellobiose, glycerol, or xylose with fructose. It produced lactic acid and ethanol but no acetic acid from glucose. The bacterium produced 21.3 +/- 0.6 g lactic acid, 10.5 +/- 0.3 g acetic acid, and 4.7 +/- 0.0 g ethanol per L of fermentation broth from dilute acid (15% solids, 0.5% H(2)SO(4), 121 degrees C, 1 h) pretreated enzyme (cellulase, beta-glucosidase) saccharified corn fiber hydrolyzate.     

Gluconic acid production byPenicillium puberulum

Twenty-five Penicillium species isolated from Egyptian soil were examined for their ability to produce gluconic acid in surface culture. Of the eight species capable of producing gluconic acid, Penicillium puberulum gave the maximum yield (91% gluconic acid from glucose after 7 days of fermentation with 3% CaCO3). Peptone was the best nitrogen source for acid fermentation and glucose was superior to sucrose. Addition of low concentrations of KH2PO4 and MgSO4 - 7 H2O stimulated acid production. An initial pH of 6.1 was most favourable for acid accumulation and addition of CaCO3 was necessary for maximum acid production.     

Synthesis of 2-keto-L-gulonic acid from gluconic acid by co-immobilized Gluconobacter oxydans and Corynebacterium sp.

2-Keto-L-gulonic acid was produced from gluconic acid using co-immobilized cells of Gluconobacter oxydans and Corynebacterium sp. with 2,5-diketo-D-gluconic acid. Gluconobacter oxydans and Corynebacterium sp. were entrapped together with polyvinylalcohol and alginate. 50 g/l glucose, 50 g/l gluconic acid, and the mixture of equal volume of 50 g/l glucose and 50 g/l gluconic acid were used as substrates. When the ratio of two cells was 1 to 1 with 100 mg cells/ml, the conversion of 2-KLG from gluconic acid was 38% (g/g). © Rapid Science Ltd. 1998     

Rubratoxin production by penicillium rubrum when grown in a synthetic medium containing different sources of carbon and nitrogen

A sterile mineral salts broth was fortified with different additives, inoculated with conidia ofPenicillium rubrum P-13, and incubated quiescently for 14 days or with shaking for 3 to 5 days. Maximal fungal growth and rubratoxin production occurred when the broth contained 20% sucrose. Broth with 10% glucose, 10% fructose, 5% maltose, or 1% asparagine supported formation of substantial amounts of rubratoxin (52.9–78.5 mg/100 ml). When the broth was fortified with glucose plus lysine, arginine aspartic acid, cystine, ammonium citrate, or ammonium phosphate, moderate amounts (27.5–39.5 mg/100 ml) of rubratoxin and mycelium (0.1–1.5 g/100 ml) were produced. Presence in the broth of 5% galactose or starch resulted in accumulation of small amounts (22.2 and 24.6 mg/100 ml, respectively) of rubratoxin and mold tissue (0.70 and 0.5 g/ 100 ml, respectively). Whereas some toxin was recovered from mineral salts broth fortified with lactose or ribose, toxin was not recovered when the mold grew in broth containing mannitol or fumarate. With the exception of gluconate which supported some growth and toxin formation and ethanol which permitted formation of small amounts of toxin, other carbon sources resulted in little or no fungal growth and no toxin formation. Yields of rubratoxin decreased with an increase in amount of agitation or length of incubation ofP. rubrum cultures. Mold growth increased and toxin formation decreased with an increase in volume of culture.     

Glutamic acid and by-product synthesis by immobilized cells of the bacterium Corynebacterium glutamicum

Summary The time course for the synthesis of glutamic acid and by-products from glucose was investigated using immobilized cell reactor of the bacterium C.glutamicum. Lactic acid, succinic acid, alanine acid and aspartic acid were formed early in the fermentation and during the active growth phase, whereas gluconic acid, -ketoglutaric acid and proline were produced late and during the active phase of glutamic acid synthesis. Oxygen transfer rate in fermentation broth had a pronounced effect on the nature and quantities of fermentation products. In continuous fermentation and at OTR of 102.5 mMO₂/l.h., formation of by-products greatly decreased and up to 58.5 g/l of glutamic acid were produced with a conversion efficiency of 74.6% of the theoretical value and volumetric productivity of 6.2 g/l.h.     

Continuous gluconic acid production by the yeast-like Aureobasidium pullulans in a cascading operation of two bioreactors

The application of a new developed process for the continuous production of gluconic acid using a cascade of two bioreactors in a continuous process is shown reaching the highest concentration of gluconic acid described in the literature for continuous culture fermentation. Very high gluconic acid concentrations of 272-308 g/l have been achieved under continuous cultivation of free-growing cells of Aureobasidium pullulans in the first bioreactor at residence times (RT) between 19.5 and 24 h with formation rates for the generic product between 12.7 and 13.9 g/(l h). Gluconic acid, 350-370 g/l, was continuously reached in the second bioreactor at a total RT of 30.8-37 h with R (j) of 9.2-12 g/(l h). The highest specific gluconic acid production (m (p)) of 3.6 g/(g h) was found in the first bioreactor at the lowest RT of 19.5 h. The highest selectivity of 93.6% was determined in the first bioreactor as well. Complete glucose consumption was obtained at 37 h total residence time in the second bioreactor. Gluconic acid, 433 g/l, was continuously produced in the second bioreactor at a total RT of 37 h.     

Effect of products of thermophilous methane fermentation on the fermentation of fruit must by Saccharomyces vini]

Experiments were carried out to study the effect of extracts from products of thermophilous methane fermentation at a dose of 0.7+2.0 ml/100 ml on the proliferation and fermentation activity of yeast Saccharomyces vini of the Yablochnaya-7 and Vishnevaya-33 race during their cultivation in the Hansen medium and in the apple and cranberry must with a normal and elevated content of sugar and acid. In some experiments the must was enriched in (NH4)2HPO4 at a dose of 0.3 g/l. Additions of small amounts of products of thermophilous methane fermentation accelerated fermentation of fruit musts with a normal sugar content and to a greater extent musts with an increased sugar content (27%). In the must enriched in (NH4)2HPO4 an almost complete (over 98%) fermentation of sugar developed for 27 days. In the must with an increased acidity (due to citric acid added to bring titrable acidity to 25 g/l) additions of the preparation also accerlerated the begining of the fermentation and increased its intensity.     

Isolation and characterization of lactic acid bacteria strains with ornithine producing capacity from natural sea salt

Two lactic acid bacteria (LAB) having ornithine-producing capacity were isolated from Korean natural sea salt. They were Gram-positive, short rod-type bacteria, and able to grow anaerobically with CO₂ production. The isolates grew well on MRS broth at 30–37°C and a pH of 6.5–8.0. The optimum temperature and pH for growth are 37°C and pH 7.0. The isolates fermented D-ribose, D-galactose, D-lactose, D-maltose, Dcellobiose, D-tagatose, D-trehalose, sucrose, D-melezitose, gentiobiose, D-glucose but not D-melibiose, inositol, and L-sorbose. The 16S rDNA sequences of the two isolates showed 99.5% and 99.6% homology with the Weissella koreensis S5623 16S rDNA (Access no. AY035891). They were accordingly identified and named as Weissella koreensis MS1-3 and Weissella koreensis MS1-14, and produced intracellular ornithine at levels of 72 mg/100 g cell F.W. and 105 mg/100 g cell F.W. and extracellular ornithine at levels of 4.5 mg/100 ml and 4.6 mg/100 ml medium, respectively, by culturing in MRS broth supplemented with 1% arginine. High cell growth was maintained in MRS broth with a NaCl concentration of 0–6%. These results show for the first time that Korean natural sea salts contain lactic acid bacteria Weissella koreensis strains having ornithine producing capacity.     

Effects of yeast, fermentation time, and preservation methods on tarhana

The physicochemical properties of tarhana soup produced with different dough treatments, fermentation times, and preservation methods were examined. Tarhana doughs were prepared with yogurt (control) or baker's yeast (Saccharomyces cerevisiae) and fermented for 3 days. Samples were taken at 24, 48, and 72 hr. Samples were then preserved via one of four methods: sun dried, dried in the shade, vacumn dried, and frozen. Frozen samples produced lower organic acid levels after 72 hr of fermentation in both control (0.68 g/100 g) and yeast (0.61 g/100 g) applications than samples that were dried (0.94 g/100 g control samples; 0.81 g/100 g samples with yeast). Increasing fermentation time resulted in a significant effect on the formation of organic acid in the tarhana (p < .01). At 72 hr of fermentation, total acidity increased 11%, 17%, and 23% for tarhana samples vacumn-dried, sun-dried, and dried in the shade, respectively. Preservation methods also affected the moisture, ash, crude protein, total acidity, pH, salt, fat, reducing sugar levels, and the sensory assestment of tarhana soup (p < .01). Sensory characteristics were not significantly affected by baker's yeast in any of the preservation methods used (p > .01). However, sensory scores for tarhana prepared from the samples dried in a sheltered area showed a reduction in color desireablilty as the fermentation time increased. The soup prepared from frozen tarhana (72 hr fermentation, with yeast) had the highest scores with respect to color, mouth feel, flavor, and overall acceptability. Vacuum-dried samples' scores in these areas were also high in comparison to the two other drying methods.     

Production of Aflatoxins B1 and G1 by Aspergillus flavus in a Semisynthetic Medium

Isolates of Aspergillus flavus produced 0.2 to 63 mg of aflatoxins B(1) and G(1) per 100 ml in a nutrient solution consisting of 20% sucrose and 2% yeast extract. Various factors influencing the fermentation were studied. The maximal amount of toxin was produced by ATCC culture 15548 in 1-liter flasks containing 100 ml of medium incubated as stationary cultures for 6 days at 25 C.     

2-酮基-D-葡萄糖酸产生菌荧光假单胞菌K1005抗噬菌体菌株的选育

从２－酮基－Ｄ－葡萄糖酸产生菌荧光假单胞菌Ｋ１００５的异学发酵液中分离到两种噬菌体,分别将其命名为ＫＳ５０２和ＫＳ５０３。电镜观察表明ＫＳ５０２呈微球形,直径为６１ｎｍ;ＫＳ５０３呈蝌蚪形,具有直径为６８ｎｍ的六角形头部及８５ｎｍ长的尾部。利用紫外线诱变的方法,经多次分离筛选,获得了２株抗性稳定且产酸水平超过对照敏感菌的抗噬菌体菌株,可以应用于生产。     

Production of lactic acid and fructose from media with cane sugar using mutant of Lactobacillus delbrueckii NCIM 2365

AIMS: To examine the potential of Lactobacillus delbrueckii mutant, Uc-3 to produce lactic acid and fructose from sucrose-based media. METHODS AND RESULTS: The mutant of L. delbrueckii NCIM 2365 was cultivated in shake flask containing hydrolysed cane sugar (sucrose)-based medium. The lactic acid yield and volumetric productivity with hydrolysed cane concentration up to 200 g l(-1) were in the range of 92-97% of the theoretical value and between 2.7 and 3.8 g l(-1) h(-1), respectively. The fructose fraction of the syrup produced was more than 95% when the total initial sugar concentration in the medium was higher (150-200 g l(-1)). There are no unwanted byproducts detected in the fermentation broth. CONCLUSIONS: We demonstrated that L. delbrueckii mutant Uc-3 was able to utilize glucose preferentially to produce lactic acid and fructose from hydrolysed cane sugar in batch fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings will be useful in the production of lactic acid and high fructose syrups using media with high concentrations of sucrose-based raw materials. This approach can lead to modification of the traditional fermentation processes to obtain value-added byproducts, attaining better process economics.