利用肌苷发酵废液生产单细胞蛋白的研究

我国在利用微生物降解酒精废液、造纸厂废液和味精厂废液等方面已有许多报道,但是,利用肌苷发酵废液作为底物进行单细胞生产还未见报道。同时,提取肌苷后的发酵废液,其营养成份仍很丰富,其中,还原糖含量约为2％,总氮含量为300mg/L～400mg/L,以及一些无机盐。COD值高达186276mg/L。目前,一般肌苷生产厂都将废液排放掉,这不仅严重地污染了环境,而且造成很大的浪费。有鉴于此,本课题进行了菌种的筛选和驯化以及工艺方面的试验。     

产氨短杆菌GMA-2802 1.2L罐肌苷发酵试验

采用诱变得来的产氨短杆菌GMA－2802,在1.2L自控发酵罐上进行了5批发酵肌苷试验,发酵周期54小时,平均产肌苷20.4g/L。结果表明该菌档是一株具有较多优良特性的肌苷产生菌。     

产氨短杆菌GMA-1112利用味精母液发酵生产肌苷

通过亚硝基胍或60 Coγ辐照等选育一株产氨短杆菌GMA 1 1 1 2 (Ade +Gua +VB1 +8 AGr+SGr+6 MPr) ,能以味精母液代替传统肌苷发酵添加酵母粉作为有机营养物 ,进行肌苷发酵 ,平均产肌苷率 2 5.4 0 g/L。具有降低发酵成本、提高产肌苷率等优点。     

肌苷产生菌B.Subtilis H841在2升罐中的发酵

枯草芽孢杆菌(Bacillus Subtilis)H841肌苷产生菌是腺嘌呤、组氨酸、硫胺素三重缺陷型菌株,并对8—氮杂乌嘌呤、6—巯基嘌呤有抗性。在摇瓶中产肌胺18.1克/升,在2L自控发酵罐中最高可产肌苷19.6克/升,在流加葡萄糖情况下可产肌苷26.2克/升。控制pH较不控制pH发酵肌苷产量有较大的增加,控制pH发酵并补加营养时,肌苷产量可稳定地增长,但对葡萄糖的转化率是相同的。     

使用硅藻土处理发酵废液、提高丁醇发酵废液回用率

以生物柴油为萃取剂耦联丁醇发酵,能以最为节能的方式生产"改良型"生物柴油、提高发酵性能,但却也产生了大量发酵废液、萃余液回用率超过50%次轮发酵就无法正常进行.探讨了使用硅藻土处理发酵废液、提高废液回用率的可能性和最适条件,在使用40目硅藻土、用量3%(w/v)的条件下,废液回用率可以提高至75%;对提高废液回用率的原因进行了初探,利用少量硅藻土可以吸附发酵残液中的丁醇,减少因美拉德反应所生成的不同分子量的增殖抑制型色素物质.原位添加微量硅藻土有利于丁醇发酵的进行,在使用油醇的萃取发酵条件下,丁醇总生产强度提高了8%.     

肌苷产生菌缺失核苷水解酶活性突变株选育及其发酵生产试验

以枯草芽孢杆菌ＪＳＩＭ－１０１９为出发菌株,经物理、化学诱变剂连续处理,获得一株缺失核苷水解酶活性的突变株ＪＳＩＭ－Ｂ－１９８。该突变株不能降解肌苷,应用于发酵生产中,肌苷产量显著增加。在２００００升发酵罐中,连续１０罐批,平均产肌苷８．３８ｇ／Ｌ,对糖转化率２１．９８％,发酵周期５０ｈ￣６０ｈ,该菌株遗传性能稳定,已在工业生产中应用。     

肌苷发酵过程中后期的代谢流节点分析

应用代谢流分析方法,实验测定副产物的积累速率,将数据输入计算机,应用MArllAB软件计算肌苷发酵中后期代谢流分布。通过分析代谢网络中重要的节点,提出了优化肌苷生物合成途径的建议。     

科技信息与服务

·国内外肌苷发酵概况:肌苷又称次黄嘌呤核苷,作为药品使用,它有诸多优点:无毒,无副反应,对不同类型的心脏病及肝病都有较好的疗效。微生物发酵生产肌苷再经过磷酸化后,得到5’肌苷酸,是食品     

新型肌苷新生菌——产氨短杆菌GMBA—800选育和特性的初步研究

采用多种方法诱变获得一株新型肌苷产生菌－－产氨短杆菌ＧＭＢＡ－８００,对其生长和发酵条件进行初步研究。肌苷产量从５ｇ／Ｌ提高到１８．４１ｇ／Ｌ,发酵周期从８４ｈ缩短为６３ｈ。菌株遗传性状稳定。     

肌苷产生菌枯草芽孢杆菌Bs菌株的选育和发酵条件

1．用枯草芽孢杆菌(Bacillus subtilis)腺嘌呤营养缺陷型(ade-)No 18经1次亚硝基胍(MNNG)。诱变处理及2次单菌落分离,获得了能利用酶法制造葡萄糖3次结晶母液,发酵生产肌苷的变异菌株B,。在适宜条件下,摇瓶肌苷产量在7.0克／升以上。 2．不同来源的酵母粉及其在培养基中的含量,对肌苷产量均有显著影响。在所试验的酵母粉中,以北京光华木材厂生产的圆酵母最好,在种子和发酵培养基中的逢合用量分别为1.0一1.4％和1.2一1.4％。 3．在发酵过程中,次黄嘌呤的积聚和肌苷积聚有着明显的消长关系。4．枯草芽孢杆菌B4菌株具有很强的分段合成肌苷的能力,当添加0．3％次黄嘌呤时,可获得高于对照93．3％的肌苷产量,但转化率以添加0．1％次黄嘌呤时为最高。     

Sauerkraut waste: a favorable medium for cultivating yeasts

Sauerkraut waste was found to be more favorable for cultivating yeasts than malt extract broth and as good or better than peptone dextrose broth.     

Efficient decomposition of shrimp shell waste using <Emphasis Type="Italic">Bacillus cereus</Emphasis> and <Emphasis Type="Italic">Exiguobacterium acetylicum</Emphasis>

Two bacterial cultures were isolated and tested for degradation of shrimp shell waste. According to morphological examination, physiological tests, and applied molecular techniques, isolates were identified as Bacillus cereus and Exiguobacterium acetylicum. Both strains were cultivated separately in flasks with 100 mL of shrimp shell waste broth (3% of washed, dried and ground shrimp shell waste in tap water, pH 7.0) at 37°C. At determined periods of time, deproteinization and demineralization of residuals were measured. Fermentation of 3% shell waste with B. cereus indicated 97.1% deproteinization and 95% demineralization. For E. acetylicum, the level of deproteinization and demineralization was 92.8 and 92%, respectively. Protein content was reduced from 18.7 to 5.3% with B. cereus and to 7.3% with E. acetylicum. No additional supplements were used during the fermentation of shell waste. B. cereus strain showed higher efficacy in decomposition of shell waste and was used for large-scale fermentation in 12 L of 10% shrimp shell waste broth. Incubation of bacteria with shell waste during 14 days at 37°C resulted in 78.6% deproteinization and 73% demineralization. High activity of isolated cultures in decomposition of shrimp shell waste suggests broad potential for application of these bacteria in environmentally friendly approaches to chitin extraction from chitin-rich wastes.     

Use of waste Chinese cabbage as a substrate for yeast biomass production

The possibility of using waste Chinese cabbage (Brassica campestris) as a substrate for microbial biomass production was investigated. The juice from waste Chinese cabbage contains relatively high amounts of reducing sugars suitable for yeast culture. The cell mass and protein content of four species of yeast, Candida utilis, Pichia stipitis, Kluyveromyces marxianus, and Saccharomyces cerevisiae, were determined when cultured in juice extracted from cabbage waste. Compared to YM broth containing the same level of sugar, all the strains except C. utilis showed higher total protein production in cabbage juice medium (CJM).     

Laboratory production and characterization of a new biosurfactant from <Emphasis Type="Italic">Candida glabrata</Emphasis> UCP1002 cultivated in vegetable fat waste applied to the removal of hydrophobic contaminant

Biosurfactant production by Candida glabrata was studied using vegetable fat waste as substrate. A factorial design was initially carried out to investigate the effects and interactions of waste, yeast extract and glucose on the surface tension after 144 h cultivation. Maximum surface tension reduction was achieved with vegetable fat waste at 5% and yeast extract at 0.2%. The biosurfactant containing cell-free broth retained its surface-active properties after incubation at high temperatures, at a wide range of pH values and salt concentrations. Comparison between three solvent systems for surfactant recovery showed that ethyl acetate extracted both crude extracellular and intracellular biosurfactant with high product recovery. The isolated extracellular biosurfactant showed a CMC of 1% and the surface tension at that point was 24 mN m⁻¹. Preliminary chemical composition revealed the presence of carbohydrates, proteins and lipids. The application of the crude biosurfactant to a soil–water-hydrophobic contaminant system was investigated and the apparent critical micelle concentration was determined at 7% of the broth, although the best oil removal (92.6%) had been obtained with 10% of the cell-free broth. The cost of application of the biosurfactant in soils was estimated based on the cost of a commercial biosurfactant.     

微生物絮凝剂产生菌的筛选及其培养条件优化

从广西大学食用菌废弃料中分离出7株絮凝剂产生菌,以发酵液对高岭土悬浮液絮凝效果为指标衡量其絮凝活性及产絮凝剂能力,经过初筛与复筛,筛选到一株絮凝剂高产菌F00,初步确定属曲霉属(Aspergillus),并对其产生絮凝剂的条件进行优化.     

Utilization of modified waste from the antibiotic industry for the production of construction materials

Possible utilization of treated streptomycin fermentation broth modified with waste hydrochloric acid solution followed by lime neutralization was studied. Such a complex additive to concrete increased its strength by 36-41 per cent. With saving cement by 7 per cent the concrete strength increased by 22-29 per cent as compared to the control samples. Therefore, utilization of antibiotic industry waste in production of building material allowed not only to improve its quality but also to lower the environmental pollution.     

Keratinolytic potential of a novel Bacillus sp. P45 isolated from the Amazon basin fish Piaractus mesopotamicus

Bacillus sp. P45, isolated from the intestine of the Amazon basin fish Piaractus mesopotamicus, showed proteolytic activity when grown on skimmed milk and feather meal agar plates. The keratinolytic potential of this strain was evaluated on whole feather broth and human hair broth. Bacillus sp. P45 degraded almost 90% of chicken feathers after 72 h of submerged cultivation on whole feather broth, and the production of extracellular proteases was observed. The formation of thiol groups was also detected during growth, indicating the contribution of sulphitolysis to the efficient hydrolysis of feather keratin. Nevertheless, Bacillus sp. P45 was unable to degrade hair keratin, possibly due to the conformational diversity of this substrate in comparison to feather keratin. Additionally, preliminary results demonstrated that this strain might be utilized in the degradation of recalcitrant collagen-containing wastes. The keratinolytic character of Bacillus sp. P45 might be utilized in environmental-friendly processes such as bioconversion of waste feathers, representing an alternative way of waste management that could lead to the production of value-added products such as microbial biomass, protein hydrolysates and proteolytic enzymes.     

双极膜电渗析分离发酵液中L-乳酸

采用三室型双极膜电渗析装置将发酵液中的L-乳酸钠转化为L-乳酸。探讨操作电压、流速、进料L-乳酸钠质量浓度等工艺参数对转化过程的影响,考察电渗析过程参数对转化率、物料损失率、电流效率和能耗等技术指标的影响。在最优操作条件下（流速40L／h,电压15V）对2L的100．25g／L乳酸钠发酵液进行分批重复电渗析处理。结果表明：整个过程的转化率为81．22％,损失率为1．5％,能耗为0．81kW·h／kg,电流效率为91．8％,得到的L-乳酸质量浓度可达144．31g／L．电渗析残液补糖后可回到发酵罐中用于发酵生产L-乳酸.     

Extractive recovery of products from fermentation broths

Considerations of partition coefficients, selectivity, biocompatibility, and waste generation are important in selection of appropriate solvents to be used for extractive recovery of products from fermentation broths. Several selection criteria can be used based upon the nature of different species present in the broth. These criteria, along with examples of specific case studies, were presented. These serve not only in screening of useful solvents, but also in pointing to the specific modes of operation of recovery-coupled bioprocesses.     

Production of microbial protein from waste cellulose by Thermomonospora fusca,a thermophilic actinomycete

The growth characteristics of Thermomonospora fusca, a cellulolytic thermophilic actinomycete, are described in terms of growth on pulping fines, a cellulosic waste of the paper industry. A fermentation was developed which substantially degrades this waste, with the residual product of growth containing about 30% microbial protein. This protein, as shown by a preliminary feeding study with baby chicks and by amino acid analyses, appears to be of good nutritional quality and contains no strongly toxic materials. The extracellular cellulolytic enzymes present in the spent broth are discussed in relation to their potential recovery as a by-product of the fermentation, as is also the possible use of the fermentation as a waste disposal system.