The fermentation of rice for anka pigment production

Optimal physical parameters of the solid state fermentation of rice to produce anka pigments and their influences on pigment production were studied. Anka pigment production, especially that of two orange anka pigments (rubropunctatin and monascorubrin), was highly sensitive to the moisture content of the rice substrate. Optimal initial moisture content of rice substrate was 24%. Pigment formation was retarded when extra water was added to the inoculated substrate during cultivation. High filling amount of rice substrate in a flask was unfavorable for pigment production. Loosening of the inoculated substrate once a day enhanced pigment production. With a high carbon dioxide level in the incubator, no orange pigments were detected. Freeze drying the fermented material produced a superior yield of anka pigments, while oven drying at 50°C for 24 h was a reasonable alternative. Journal of Industrial Microbiology & Biotechnology (2000) 25, 141–146. Received 27 December 1999/ Accepted in revised form 24 June 2000     

阿魏蘑液体发酵过程菌体形态变化对产漆酶的影响

本文旨在研究阿魏蘑菌体形态与漆酶产量之间的关系。结果显示,玻璃珠的添加可改变发酵过程中菌体形态,漆酶产量在球状菌体条件下高于丝状、絮状菌丝：直径分布在0.2~0.4 mm范围的菌球对漆酶的合成具有明显的促进作用;适合的葡萄糖、玉米粉和麸皮添加量,对直径在0.2~0.4 mm范围的菌球形成具有重要影响。此外,添加惰性载体同样可以控制菌球的直径分布,但对漆酶的合成无促进作用。     

Change of Monascus pigment metabolism and secretion in different extractive fermentation process

Bioprocess and Biosystems Engineering - Monascus pigments that were generally produced intracellularly from Monascus spp. are important natural colorants in food industry. In this study, change of...     

Variations in Monascus pigment characteristics and biosynthetic gene expression using resting cell culture systems combined with extractive fermentation

Applied Microbiology and Biotechnology - Monascus pigments are promising sources of natural food colorants, and their productivity can be improved by a novel extractive fermentation technology. In...     

Effect of light on growth,pigment production and culture morphology of <Emphasis Type=Italic>Monascus purpureus</Emphasis> in solid-state fermentation

The capacity to sense and respond to light is widespread in animals, plants, fungi and bacteria. The effect of light quality on growth and pigment yield of Monascus purpureus was investigated. Incubation in total darkness increased red pigment production from 14. 5 OD/g dry substrate to 22 OD/g dry substrate. In contrast, growth of the fungus in direct illumination resulted in total suppression of pigment production. It was found that both red and blue light influenced pigment yield as well as culture morphology. The authors propose the existence of a light-perception system in Monascus purpureus.     

氯过氧化物酶发酵相关指标及其关联性分析

通过考察氯过氧化物酶(CPO)发酵相关参数的动力学特征,探究酶产量与参数之间的关联性。结果表明:CPO发酵过程中慢速C源麦芽糖比葡萄糖更有利于调控CPO的稳定合成,前者CPO最高比酶活(179.50 U/m L)比后者(135 U/m L)高出44.5 U/m L,而且产酶高峰期延迟1~2 d;发酵过程p H波动与C源消耗速率密切相关,且对CPO合成具有明显的指标性作用。通过生物量曲线及糖消耗曲线与产酶特征对比判断,菌株合成CPO为中期合成类型。副产物黑色素是菌体成熟时期的一种次生代谢物质,与酶的生物合成存在时间上的同步性。控制C源基质和p H对提高CPO稳定化生产具有一定成效。     

玉米浆对林可链霉菌的代谢特性及形态的动态影响

菌丝形态的定量计算表明,添加玉米浆后,菌团核心面积、菌丝面积、圆形因子和边缘菌丝密度等形态学参数均呈上升趋势,菌丝形态得到明显改善,中后期和后期的平均比生长速率增大,菌体的维持代谢和次级代谢保持在较高较稳定水平,有效解决了中后期及后期林可链霉菌的比生长速率为负及林可霉素产量的增长幅度很小的问题。     

提高丁醇萃取发酵耦联生产改良型生物柴油过程中萃余液回用效率的研究

利用少量廉价的萃取剂一正辛醇（正辛醇／萃余液体积比0．2：1）对萃余液中的丁醇进行萃取,萃余液中56％的残余丁醇可被回收,总丁醇得率提高了38％。萃余液经活性炭（3％,w／v）处理后,在100％回用拌料条件下一批次发酵能够正常进行。萃取发酵条件下,反复全回用萃余液5次,萃取发酵性能可以保持稳定。为丁醇萃取发酵耦联生产改良型生物柴油过程中萃余液的全回用提供了一种新型、低成本和绿色环保的方法。     

Coupling of fermentation and microfiltration for α-amylase production from Bacillus amyloliquefaciens

Abstract: A strain of Bacillus amyloliquefaciens secreting α-amylase was cultivated continuously in a fermentor coupled to a filtration unit. Under the tested operating conditions, the maximum flux was 91 m^-2 h^-1 during the first day and 61 m^-2 h^-1 during the 2nd day. The α-amylase retention was around 30%. Compared to a batch process, continuous cultivation with cell recycling led to lower α-amylase concentrations but to a doubling of volumetric productivities.     

丝状真菌形态控制及其在发酵过程优化中的应用

丝状真菌广泛用于发酵产业,在液体深层发酵过程中,其生长形态与产物种类及产量间存在重要关联,成为发酵过程调控的热点。采用数学模型解释丝状真菌的形态发育与调控机制,是近年来工程学界颇为关注的研究手段。本文结合自己的工作着重解释丝状真菌各种生长形态的生长机理及形态发育的数学描述方式,以及如何采用数学模型描述丝状真菌发酵过程中产物、形态及环境的关联,最终实现形态的控制,完成生物发酵过程优化。具体包括:1)丝状真菌的生长机制;2)形态发育数学模型在发酵过程优化中的应用;3)控制丝状真菌形态的策略。     

Comparison of oxygen mass transfer coefficient in simple and extractive fermentation systems

Aeration and agitation are important variables to ensure effective oxygen transfer rate during aerobic bioprocesses; therefore, the knowledge of the volumetric mass transfer coefficient (k_La) is required. In view of selecting the optimum oxygen requirements for extractive fermentation in aqueous two-phase system (ATPS), the k_La values in a typical ATPS medium were compared in this work with those in distilled water and in a simple fermentation medium, in the absence of biomass. Aeration and agitation were selected as the independent variables using a 2² full factorial design. Both variables showed statistically significant effects on k_La, and the highest values of this parameter in both media for simple fermentation (241 s⁻¹) and extractive fermentation with ATPS (70.3 s⁻¹) were observed at the highest levels of aeration (5 vvm) and agitation (1200 rpm). The k_La values were then used to establish mathematical correlations of this response as a function of the process variables. The exponents of the power number (N³D²) and superficial gas velocity (V_s) determined in distilled water (α = 0.39 and β = 0.47, respectively) were in reasonable agreement with the ones reported in the literature for several aqueous systems and close to those determined for a simple fermentation medium (α = 0.38 and β = 0.41). On the other hand, as expected by the increased viscosity in the presence of polyethylene glycol, their values were remarkably higher in a typical medium for extractive fermentation (α = 0.50 and β = 1.0). A reasonable agreement was found between the experimental data of k_La for the three selected systems and the values predicted by the theoretical models, under a wide range of operational conditions.     

虫草发酵菌丝体对胰岛素抵抗大鼠氧化应激的缓解作用

探究虫草发酵菌丝体对胰岛素抵抗(IR)大鼠氧化应激的影响。采用低中高剂量虫草发酵菌丝体(剂量分别为1.65g/kg饲料,3.30g/kg饲料和6.60g/kg饲料)分别干预IR大鼠。口服葡萄糖耐量实验观察不同剂量虫草发酵菌丝体的降糖效果,同时观察血脂、氧化应激水平的变化情况。RT-PCR法测肌肉、肝脏组织氧化应激相关基因Nrf2、HO-1和NQO1mRNA相对表达量,Westernblot法测其蛋白相对表达量。结果发现CM干预能够显著改善IR大鼠空腹血糖、血脂和机体氧化应激水平,肌肉、肝脏组织Nrf2、HO-1和NQO1mRNA相对表达量显著上升,肝脏Nrf2和NQO1蛋白相对表达量显著上调,并且具有剂量依赖性。说明CM具有缓解IR大鼠氧化应激的作用。     

粗糙脉孢菌纤维素酶液体发酵优良形态突变体筛选

丝状真菌被广泛地用于包括纤维素酶在内的工业酶生产过程。在液体深层发酵中,丝状真菌菌丝形态直接影响发酵液的流变特性,进而与目标酶蛋白产量存在着重要的关联。目前,针对丝状真菌工业酶液体发酵菌丝形态的研究依然是从传统的发酵工程学角度出发,对与发酵水平紧密相关的形态、粘度等性状相关基因的认识远远不够。为了挖掘深层发酵中对丝状真菌发酵产酶性能具有重要影响的形态发育相关基因,以粗糙脉孢菌Neurospora crassa单基因突变体库中的95株形态突变株为研究对象,在结晶纤维素为碳源的条件下进行筛选,探寻与野生型菌株蛋白产量有显著差异的突变株。同时,对这些突变株的内切-β-1,4-葡聚糖酶酶活、β-葡萄糖苷酶酶活、发酵液粘度和菌丝干重进行了测定,并观察了发酵液中突变株的菌丝形态。实验结果表明,与野生型菌株相比,突变株SZY32、SZY35、SZY39和SZY43发酵液中蛋白浓度显著降低,突变株SZY11、SZY63、SZY69和SZY87发酵液中蛋白浓度显著性提高。值得注意的是,突变株SZY11和SZY43发酵液菌丝体主要形态为菌球状,其发酵液粘度分别降低75%和50%,突变株SZY87在发酵液中呈长丝状,发酵液粘度显著升高至少2倍。这些与产酶水平相关的形态、粘度基因的获得将有助于丝状真菌纤维素酶等工业酶高产工程菌株的理性构建。     

Continuous production of isovaleraldehyde through extractive bioconversion in a hollow-fiber membrane bioreactor

A membrane bioreactor was developed to perform an extractive bioconversion aimed at the production of isovaleraldehyde by isoamyl alcohol oxidation with whole cells of Gluconobacter oxydans. A liquid/liquid extractive system using isooctane as extractant and assisted by a hollow-fiber hydrophobic membrane was chosen to recover the product. The aqueous bioconversion phase and the organic phase were maintained apart with the aid of the membrane. The extraction of alcohol and aldehyde was evaluated by performing equilibrium and mass transfer kinetic studies. The bioprocess was then performed in a continuous mode with addition of the substrate to the aqueous phase. Fresh solvent was added to the organic phase and exhausted solvent was removed at the same flow rate. The extractive system enabled a fast and selective in situ removal of the aldehyde from the water to the organic phase. High conversions (72–90%) and overall productivity (2.0–3.0 g l⁻¹ h⁻¹) were obtained in continuous experiments performed with different rates of alcohol addition (1.5–3.5 g l⁻¹ h⁻¹). Cell deactivation was observed after 10–12 h of operation.     

华根霉液态培养生产脂肪酶不同形态菌体的转录组差异分析

【背景】作为发酵工业中一类重要的生产菌株,丝状真菌目的产物的形成与菌体形态有着紧密的联系。华根霉(Rhizopus chinensis)CCTCC M201021是从我国传统酿造浓香型白酒大曲中筛选到的一株丝状真菌,其生成的包括脂肪酶在内的酶蛋白具有较高的工业应用价值。【目的】华根霉(Rhizopus chinensis)CCTCC M201021在脂肪酶液态发酵中形成两种不同形态菌体,发酵表现差异明显。本研究考察华根霉不同菌体形态及其细胞代谢在转录组水平的内在差异。【方法】基于RNA-Seq高通量转录组测序,分别对液态培养获得的不同形态华根霉菌体高表达和显著差异表达的转录基因进行功能分析。【结果】两种形态菌体转录组存在明显的差异。利用RPKM值对表达量最高的前20个基因进行分析,聚集态菌体高表达基因主要为不同类别的核糖体蛋白,而分散态菌体中与细胞形态相关的几丁质酶及与信号传导相关的基因也是高表达基因。在两种形态菌体显著差异表达的20个基因中,除了涉及代谢的基因有明显不同外,分散态菌体中也有一些涉及"细胞过程与信号"的基因上调表达显著。两种形态菌体中独有表达基因总体表达量均较低,但聚集态菌体独有表达基因在基因种类和表达量上都要明显高于分散态菌体。同时,转录分析表明,华根霉脂肪酶在聚集菌体中较高的生产水平与脂肪酶基因的高水平转录有关。【结论】菌体形态的差异显著影响了华根霉的转录组,不仅不同形态菌体高表达基因和显著差异表达基因有明显不同,而且功能相同的蛋白在不同菌体形态下也多是由不同基因表达,它们可能承担着不同的作用。总体而言,华根霉聚集态菌体中存在更为复杂的生理过程,而分散菌体中受到信号的传导和调控似乎更多。菌体形态的改变可能是细胞分化的结果,伴随着菌体对细胞微环境改变的一种响应。研究结果为深入了解丝状真菌形态分化的内在机制及其影响提供了一些线索。     

Submerged fermentation in wheat substrates for production of Monascus pigments

Cereal grains are normally used as solid substrates for the production of Monascus metabolites. However, solid fermentation in these substrates requires complex control systems, whereas in liquid culture the control of the fermentation is simpler and consequently significant reductions in fermentation times can be achieved. In the same way, the use of submerged culture can benefit the production of many secondary metabolites and decrease production costs by reducing the labour involved in solid-state methods. A flour composed of a mixed variety of Canadian hard wheat was used as sole nutrient source to produce the pigments of Monascus purpureus Went (IMI 210765). Supplementation with NH₄Cl promoted biomass and orange dye formation, whereas the use of zinc sulphate favoured red dyes production. In submerged fermentations significant differences in final pigment yields were observed in the use of wheat-based broth at different concentrations in the presence of bran particles and/or gluten protein. It has been found that the viscosity of the broth had a significant effect on the growth morphology and production of pigments. Gluten-free wheat flour at concentrations of 3–5% was found to be the most suitable for liquid Monascus culture. The subsequent use of passive immobilization of Monascus served to enhance red pigment yields and to facilitate the downstream processing of the dyes.     

Response surface optimization of mixed substrate solid state fermentation for the production of lovastatin by Monascus purpureus

The objective of this work is to enhance the production of lovastatin using Monascus purpureus MTCC 369 in mixed substrate solid state fermentation using various solid substrates and to optimize the combination of the solid substrates by response surface methodology. Solid state fermentation was conducted in a 250 mL Erlenmeyer flask at 30°C for 14 days with initial moisture content of 40% and inoculum size of 10% active culture. Barley, long grain rice and sago starch were found to be the suitable substrates producing maximum lovastatin of 193.7 mg, 190.2 mg and 180.9 mg/g of dry solids. These substrates were further used in various combinations as designed by the central composite design for enhancing the lovastatin production using Monascus purpureus. To the best of our knowledge this is the first report on the production of lovastatin using a mixed substrate solid state fermentation using Monascus purpureus.     

Partitioning of pristinamycins in aqueous two-phase systems: A first step toward the development of antibiotic production by extractive fermentation

The partitioning of pristinamycins was studied in dextran and polyethylene glycol (PEG) aqueous two-phases systems. Pristinamycins partitioned preferentially into the PEG-rich top phase. The partition coefficient was independent of molar mass of PEG and dextran and of antibiotic concentration, but, increased exponentially with the tieline length of the system. Partition of pristinamycins was greatly improved when fatty acids esters of PEG were mixed with PEG. In such mixtures, the partition of coefficient increased up to a value of 24, dependent on the carbon chain length of fatty acids and the modified PEG concentrations. Moreover, in such system, the two groups of pristinamycins, I and II, were extracted in accordance with their hydrophobicity. Recovery of pristinanamycins produced by Streptomyces pritinaespiralis in a fermentation broth was achieved with a dextran/PEG system. Cells were confined into the bottom phase and pristinamycins partitioned in the top phase. However, due to binding of the pristinamycins to the cells, the partition coefficient was slightly lower than of pure antibiotics solutions. (c) 1994 John Wiley & Sons, Inc.     

Analysis of mass transfer for immobilized cells in an extractive lactic acid fermentation

The use of immobilization in extractive lactic acid fermentation by Lactobacillus delbrueckii is preferred. In this article, the mathematical simulations to examine the influences of substrate and product transport were performed to assess the overall performance. The simulations showed that transport of the substrate in k-carrageenan beads was not a rate limiting factor. However, the model observed significant buildup of inhibitory product in large beads. The model was validated through comparisons with the experimental results. Finally, the model was used to predict the performance of the extractive fermentation under different operating strategies.