固态间歇补料乙醇生料发酵新工艺

浓醪发酵是酒精生产的发展方向。与现行酒精厂普遍采用的热蒸煮工艺相比, 生料发酵技术的发展使得浓醪发酵更容易进行。本研究首次在生料发酵中直接采用固态原料间歇补料, 比较了STARGENTM生淀粉水解酶间歇补料工艺和传统无补料工艺, 并对不同补料方式进行了研究。结果表明: 与传统无补料生料发酵工艺相比, 在相同的干基配料浓度30%、相同的生料酶添加量0.22%(W/W)的条件下, 采用15%的起始配料浓度、发酵15~25 h进行间歇补料的新工艺, 酒精产量从17.06%提高到18.50%。该间歇补料优化工艺的建立, 丰富了生料发酵技术的应用。     

乙醇-黄原胶耦联两步发酵

初步探索乙醇-黄原胶耦联两步发酵的可行性和生产工艺,即控制乙醇发酵,发酵液去除固形物后蒸馏回收酒精,然后利用酒精糟液中剩余营养物质进行黄原胶发酵。摇瓶和小罐试验证实方案是可行的,耦联发酵工艺优化条件:选择木薯淀粉进行乙醇发酵60 h后的酒精糟液,添加2 g/L KH2PO4,不添加无机N源。在优化条件下,7 L发酵罐中耦联发酵的黄原胶产量达到20 g/L,转化率约为50%。     

Industrial chemicals from fermentation

This paper examines the potential for carbohydrate fermentation as an alternative process technology for bulk organic chemicals. Major limitations restricting the broadening of scope for fermentation chemicals are identified. These involve the high process energy requirements in pretreating abundant cellulosic feedstocks, low overall conversion, low weight yield and limited product applications of directly biosynthesized fermentation chemicals. The new development directions for chemicals derived directly and indirectly from carbohydrate fermentation are reviewed. The significance of their potential impact on the evolving organic chemical industry is projected.     

A combined phenolic extraction and fermentation reactor engineering model for multiphase red wine fermentation

Red wine production begins with a simultaneous fermentation and solid-phase extraction process. Red wine color and mouthfeel is the result of the extraction of phenolics from grape skins and seeds during fermentation, where extraction is a strong function of temperature and ethanol concentration. During fermentation, grape solids form a porous “cap” at the top of the fermentor, resulting in a heterogeneous fermentation system with significant temperature and concentration gradients. In this work, we present a spatial, time-variant reactor engineering model for phenolic extraction during red wine fermentation, incorporating fermentation kinetics, mass transfer, heat transfer, compressible fluid flow, and phenolic extraction kinetics. The temperature and ethanol concentration profiles predicted by this model allow for the calculation of phenolic extraction rates over the course of fermentation. Phenolic extraction predictions were validated against prior experimental data to good agreement and compared to a well-mixed model's predictions to show the utility of a spatial model over well-mixed models.     

Acetonobutylic fermentation: improvement of performances by coupling continuous fermentation and ultrafiltration

The technology of coupling ultrafiltration and fermentation has been tested with the acetonobutylic fermentation in continuous mode. The device developed was sterilizable by steam and permitted drastic cleaning of the ultrafiltration (UF) membrane without interrupting the continuous fermentation. It has been shown to be an easily operated and reliable experimental tool for studying high-cell-density cultures and inhibition phenomena. With total recycle of biomass, a dry weight concentration of 125 g/L was attained, which greatly enhanced the volumetric solvent productivity of acetonobutylic fermentation in averaging 4. 5 g/L h for significant periods of time (>70 h) and maintaining solvent concentration and yield at acceptable levels.     

论植物发酵和酵素

摘要：本文根据作者多年从事发酵工业科研与生产实践的经验,结合自身对酵素的认识和理解,就酵素的起源、机体抗衰老学说、植物原料的微生物发酵与几种药食两用植物和水果经微生物发酵而提高其生物活性的研究作了介绍,最后就酵素的发展提出了建议。     

Oxygen solubilities in fermentation fluids

Summary Fermentation media consist of a large number of chemicals whose composition undergoes alteration during the course of fermentation. As a result of this, conventional methods and correlations for oxygen solubility measurement and prediction do not apply in these systems. Using a physical method, oxygen solubilities were measured in simulated chemical systems and in fermentation broths. Sugars, salts, and fermentation products were identified as major factors influencing oxygen solubility. Salt effect was correlated with electrical conductivity of the medium, which was easy to measure during fermentation. For mixtures and for fermentation medium, individual influences were found to be log-additive in accordance with Danckwerts (1970).     

Continuous fermentation in slant tubes

Continuous, steady-state grape-juice fermentation, carried out in experimental slant-tube fermentors, was characterized by complete fermentation, even at fast pumping rates, because efficient cell retention, as well as rapid yeast growth, quickly built cell density up to the limit permitted by the juice supply rate. Essentially complete fermentation was easily achieved with a juice residence time of 3.1 hr, compared to about 120 hr in normal batch fermentation. Successful continuous fermentation required constancy of gas and liquid flow through the tubes, placing some restrictions on choice of tube configurations. The validity of design equations, developed previously from a settling model, was tested, and some practical aspects of their application to fermentor design and operation were demonstrated.     

Comparative study of protease production in solid substrate fermentation versus submerged fermentation

Attempts have been made to compare solid substrate fermentation (SSF) with submerged fermentation for the production of proteases by Bacillus amyloliquefaciens. In submerged fermentation it produced 800,000 units of enzyme under optimal conditions in a 20-litre fermentor whereas in solid substrate, it produced 250,000 units/g. Owing to the simplicity and easiness of operation of SSF and for applications like unhairing, biodetergents and bating the former would be advantageous for the production of proteases.     

Rheometry of fermentation liquids

This article is concerned with the measurements of rheological properties of nonhomogeneous fermentation liquids. In order to determine the flow curves of such liquids, an impeller measuring system of own design was used, and the method of calibration of the system is presented. The experimental verification was carried out using samples of fermentation broth of Aureobasidium pullulans and it has been shown that the applied measuring technique gives internally consistent results. The sensitivity of the technique proves its applicability for monitoring and control purposes in fermentation technology.     

Kocho fermentation

Kocho, an acidic starchy food, is prepared by fermenting a mixture of the scraping of the trunk and pulverized stem and corm of ensette ( Ensette ventricosum). Leuconostoc mesenteroides is responsible for initiating the fermentation. Because of the activities of this species and, to some extent, of Streptococcus faecalis , the pH of the fermenting kocho was reduced from 6˙5 to 5˙6. These organisms were then succeeded by the homofermentative bacteria Lactobacillus coryneformis subsp. coryne-formis and Lact. plantarum . Through the activities of the Lactobacillus species, the pH was further reduced to 4˙2. Pediococcus cerevisiae , although present in kocho, did not achieve prominence because of the relatively low fermentation temperature (14°-18°C). Spore-formers were present in fairly high numbers during the first 15 d of fermentation. It was suspected that the butyrous odour which was detected during the first 2 weeks in fermenting kocho might be due to the activities of certain clostridial species. Yeasts were also present in fairly high numbers.     

Kinetics of fermentation processes

Kinetic studies on fermentation processes were made and a general equation of production rate was newly presented applying the kinetic theory on mierobial cell growth which was reported previously by the authors.^l,2 Equations for product concentration in fermentation time courses were derived by developing mathematically the general equation of production rate, and characteristic properties of fermentation processes were clarified. Some examples of fermentations were analyzed kinetically using the new kinetic theory. The calculated values of product, and cell concentrations were in good agreement with the observed values.     

Membrane-integrated fermentation system for improving the optical purity of D-lactic acid produced during continuous fermentation

This report describes the production of highly optically pure D-lactic acid by the continuous fermentation of Sporolactobacillus laevolacticus and S. inulinus, using a membrane-integrated fermentation (MFR) system. The optical purity of D-lactic acid produced by the continuous fermentation system was greater than that produced by batch fermentation; the maximum value for the optical purity of D-lactic acid reached 99.8% enantiomeric excess by continuous fermentation when S. leavolacticus was used. The volumetric productivity of the optically pure D-lactic acid was about 12 g/L/h, this being approximately 11-fold higher than that obtained by batch fermentation. An enzymatic analysis indicated that both S. laevolacticus and S. inulinus could convert L-lactic acid to D-lactic acid by isomerization after the late-log phase. These results provide evidence for an effective bio-process to produce D-lactic acid of greater optical purity than has conventionally been achieved to date.     

Extremum seeking scheme for continuous fermentation processes described by an unstructured fermentation model

This paper examines the problem of maximising the productivity of a class of fermentation processes described by an unstructured fermentation process model. For a given dilution rate, an extremum seeking adaptive control has been used to maximise the productivity of a fermentation process. The concept behinds the extremum seeking method is to iteratively adjust the feed substrate rate in order to steer the process to yield a maximum productivity. The main advantage of the extremum seeking adaptive control is it does not require any structural information of the modeling uncertainty.     

In-situ recovery of butanol during fermentation

End product inhibition can be reduced by the in situ removal of inhibitory fermentation products as they form. Extractive fermentation, in which an immiscible organic solvent is added to the fermentor in order to extract inhibitory products, was applied to the acetone-butanol fermentation. Six solvents or solvent mixtures were tested in batch extractive fermentations: kerosene, 30 wt% tetradecanol in kerosene, 50 wt% dodecanol in kerosene, oleyl alcohol, 50 wt% oleyl alcohol in a decane fraction and 50 wt% oleyl alcohol in benzyl benzoate. The best results were obtained with oleyl alcohol or a mixture of oleyl alcohol and benzyl benzoate. In normal batch fermentation of Clostridium acetobutylicum, glucose consumption is limited to about 80 kg/m³ due to the accumulation of butanol in the broth. In extractive fermentation using oleyl alcohol or a mixture of oleyl alcohol and benzyl benzoate, over 100 kg/m³ of glucose can be fermented. Removal of butanol from the broth as it formed also increased the rate of butanol production. Maximum volumetric butanol productivity was increased by as much as 60% in extractive fermentation compared to batch fermentation. Butanol productivities obtained in extractive fermentation compare favorably with other in situ product removal fermentations.     

木薯发酵产丁醇的研究

对丙酮丁醇梭菌发酵木薯产溶剂进行研究,分别考察了N源、木薯含量、酶处理条件和培养基pH对发酵产丁醇的影响。结果表明：最佳的产丁醇发酵培养基为木薯粉120g／L,乙酸铵6g／L;木薯粉先用高温淀粉酶按酶量20U／g、90℃水解60min,再糊化30min;发酵初始pH为6．0,发酵96h。在此条件下,5L发酵罐中丁醇产量达到13．5g／L,总溶剂达到22．8g／L。     

纳豆激酶液态发酵条件的研究

考察纳豆杆菌在7.5 L发酵罐中分批发酵产纳豆激酶的条件,纳豆激酶酶活采用四肽底物测定。结果表明:纳豆杆菌生长和产酶的适宜条件不一致。发酵过程中发酵罐搅拌转速控制为500 r/min不变,0～12 h时控制pH为8.0、温度为37℃;12～36 h调整pH为7.0、温度为30℃;16 h时补加外源C源,连续发酵36 h。该过程中发酵液中比酶活最高达到3 232 U/mL,与摇瓶发酵相比,比酶活提高了58%。     

An innovative consecutive batch fermentation process for very high gravity ethanol fermentation with self-flocculating yeast

An innovative consecutive batch fermentation process was developed for very high gravity (VHG) ethanol fermentation with the self-flocculating yeast under high biomass concentration conditions. On the one hand, the high biomass concentration significantly shortened the time required to complete the VHG fermentation and the duration of yeast cells suffering from strong ethanol inhibition, preventing them from losing viability and making them suitable for being repeatedly used in the process. On the other hand, the separation of yeast cells from the fermentation broth by sedimentation instead of centrifugation, making the process economically more competitive. The VHG medium composed of 255 g L⁻¹ glucose and 6.75 g L⁻¹ each of yeast extract and peptone was fed into the fermentation system for nine consecutive batch fermentations, which were completed within 8–14 h with an average ethanol concentration of 15% (v/v) and ethanol yield of 0.464, 90.8% of its theoretical value of 0.511. The average ethanol productivity that was calculated with the inclusion of the downstream time for the yeast flocs to settle from the fermentation broth and the supernatant to be removed from the fermentation system was 8.2 g L⁻¹ h⁻¹, much higher than those previously reported for VHG ethanol fermentation and regular ethanol fermentation with ethanol concentration around 12% (v/v) as well.     

Protein measurement in solid-state fermentation

Summary Membrane filter culture was used as a model system for the investigation of the growth of Rhizopus oligosporus in solid-state fermentation. The biuret method gave more accurate estimations of protein than the Folin-Lowry method. However, due to the change in the protein content of the biomass during the fermentation, protein cannot be considered to be a reliable index of growth in solid-state fermentation.     

Methionine production by fermentation

Fermentation processes have been developed for producing most of the essential amino acids. Methionine is one exception. Although microbial production of methionine has been attempted, no commercial bioproduction exists. Here, we discuss the prospects of producing methionine by fermentation. A detailed account is given of methionine biosynthesis and its regulation in some potential producer microorganisms. Problems associated with isolation of methionine overproducing strains are discussed. Approaches to selecting microorganism having relaxed and complex regulatory control mechanisms for methionine biosynthesis are examined. The importance of fermentation media composition and culture conditions for methionine production is assessed and methods for recovering methionine from fermentation broth are considered.