Effect of alternative C2 carbon sources on the growth, lipid, and γ-linolenic acid production of spirulina (Arthrospira platensis)

The influence of different organic carbon sources (glucose, ethanol, and acetic acid) at different concentrations (0.1, 0.5, and 1.0 g/L for batch and 1.0, 2.0, and 3.0 g/L for fed-batch) were studied in the mixotrophic production (using both light and carbon source) of γ-linolenic acid (GLnA) by spirulina (Arthrospira platensis). The obtained spirulina was analyzed in terms of biomass, lipid, and GLnA production. In the batch media, increasing the concentrations of glucose, ethanol, and acetic acid led to an increase in the biomass, lipid, and GLnA production. However, carbon sources at concentrations greater than 1.0 g/L in fed-batch media appeared to have no significant effects on the above parameters. It was also demonstrated that biomass, lipid, and GLnA production using ethanol and acetic acid could be as good as those achieved with the classic glucose-based culture media.     

利用廉价原料生产聚谷氨酸的研究

目的 降低聚谷氨酸的生产成本.方法 从聚谷氨酸发酵所需的氮源和碳源出发,分别研究了小麦水解蛋白、豆饼粉、豆粕粉、玉米蛋白、玉米浆等有机氮源和甘蔗糖蜜、甜菜糖蜜、葡萄糖蜜、玉米糖蜜等碳源对聚谷氨酸发酵产量的影响,在此基础上通过单因素实验优化了玉米浆、硫酸铵、甜菜蜜、谷氨酸钠的添加量,最后通过发酵罐发酵比较了优化后的工艺与...     

ISOLATION AND SELECTION OF ETHANOL-RESISTANT AND OSMOTOLERANT YEASTS FROM REGIONAL AGRICULTURAL SOURCES IN MEXICO

In Mexican alcohol distilleries using sugarcane molasses, one reason for low alcoholic fermentation efficiency is the use of inferior yeast cultures. The objective of the present study was to isolate and select yeast strains from alcoholic fermentations of natural sources (sugarcane molasses, grape juice, cane juice and pineapple) from Veracruz city market and Mexican distilleries, and to evaluate their performance under laboratory conditions in an effort to select superior strains for industrial fermentations. Ethanol production, glucose composition, growth rate, "Killer" activity, ethanol and glucose tolerance of the most promising strains were monitored on synthetic and molasses media. A total of 112 yeast strains were isolated by their capacity to produce ethanol, and from these, only 58 were selected on the basis of best ethanol theoretical yields (88–96%). These strains were exposed several times to high concentrations of glucose and ethanol in order to select ethanol- and glucose-tolerant yeast; 10 were obtained that adapted best to these conditions and that showed "Killer" activity. Of these strains, U3-11, M11, JC10 and U2-10 (obtained from grape juice, sugarcane molasses and cane juice) demonstrated the highest adaptation to both ethanol (5–7% w/v) and glucose (20% w/v). The maximum yield obtained was 0.46 g/g (90% theoretical yield) in a 20-L bioreactor with cane molasses under nonsterile conditions.

PRACTICAL APPLICATIONS

The selected yeasts could be introduced into industrial processes in Mexican distilleries using sugarcane molasses in order to improve productivity and diminish contamination problems.     

巴氏醋杆菌Ap2012的生长及耐受性研究

考察巴氏醋杆菌Ap2012在不同碳源酵母膏平板的生长情况及其对乙醇、糖、酸、NaCl的耐受性。结果表明,在酵母膏平板上,Ap2012能利用葡萄糖、乙醇作为碳源生长并产酸,能较好地利用甘油、果糖、蔗糖、山梨糖,对甘露醇的利用较差。乙醇体积分数为12.4%时巴氏醋杆菌Ap2012的生长受明显抑制,达到15.8%时转酸能力受明显抑制。葡萄糖的质量浓度达到300 g/L,NaCl的质量浓度为15 g/L时,巴氏醋杆菌Ap2012的生长和转酸能力受到明显抑制。乙酸质量浓度达到42 g/L时,巴氏醋杆菌Ap2012的生长受到明显抑制。结果表明,巴氏醋杆菌Ap2012对高浓度糖及乙醇有较好的耐受性,对乙酸和NaCl的耐受性较差。     

流加混合碳源的谷氨酸发酵工艺研究

采用糖蜜与葡萄糖的混合液作为流加碳源，对谷氨酸发酵工艺进行了探索。试验采用葡萄糖为基础碳源，以发酵初糖浓度为160g／L的培养基进行谷氨酸发酵，以糖蜜与葡萄糖的混合液为流加碳源，结果表明当糖蜜中还原糖占混合液总还原糖30％时，发酵产酸水平和糖酸转化率分别达到142.2g／L和64．88％，与葡萄糖作为唯一流加碳源的谷氨酸发酵工艺比较，其发酵水平十分相近。但生产谷氨酸的碳源成本可降低5％左右。     

Fermented sugarcane and pineapple beverage produced using Saccharomyces cerevisiae and non‐Saccharomyces yeast

The potential of Saccharomyces cerevisiae (strains UFLA CA11 and UFLA FW15) and Pichia caribbica (UFLA CAF733) to produce a fermented sugarcane and pineapple drink was evaluated. Co‐ and pure cultures using different proportions of sugarcane juice and pineapple pulp (80:20, 70:30 and 60:40) were prepared. The sugar concentration of the must was adjusted to 16° Brix and was inoculated with approximately 7 log CFU/mL. After a preliminary test and based on higher concentrations of desirable volatile components, low production of acetic acid, high production of ethanol, and kinetic parameters, P. caribbica was chosen to perform the fermentation in 5 L batches. The fermentation performed with P. caribbica in the proportion of 60:40 showed a yield in ethanol of 0.45 g/g, an ethanol productivity of 1.32 g/L/h and a fermentation efficiency of 88.22%. The maximum ethanol concentration was 79.78 g/L and P. caribbica increased concentrations of desirable volatile compounds, such as 2‐phenyethanol, 2‐methyl‐1‐propanol, 3‐methyl‐1‐butanol, ethyl acetate and phenylethyl acetate. Copyright © 2015 The Institute of Brewing & Distilling     

农副产品发酵产微生物胞外多糖PS-9415的研究

采用甘蔗糖蜜、葡萄糖浆、大豆粕和花生粕分别作为微生物胞外多糖PS-9415发酵培养基的碳源和氮源,结果表明大豆粕发酵产胶量13.2g/L,葡萄糖浆(30g/L)为发酵培养基时,能得到较高产量15.5g/L。甘蔗糖蜜(50g/L)也能得到较高的产量13.9g/L和表观粘度1.64Pas。     

Starch Hydrolysate,an Optimal and Economical Source of Carbon for the Secretion of Citric Acid by Yarrowia lipolytica (DS-1)

Using Yarrowia lipolytica (DS-1), secretion of citric acid is studied as a function of carbon sources such as glucose, fructose, hydrol, sucrose, cane sugar molasses, kerosene (all available commercially) and tapioca starch hydrolysate, invert sucrose and invert cane sugar molasses (all prepared in laboratory). On the basis of their acceptability by DS-1 for citric and isocitric acid secretion, it is concluded that (a) sucrose and cane sugar molasses (with/without inversion) served as poor carbon sources, (b) fructose, hydrol, impure tapioca starch hydrolysate (96 DE w/w) and invert sucrose served as relatively better carbon sources and (c) purified tapioca starch hydrolysate (96 DE w/w) was the best carbon source to substitute glucose by giving comparable (75%) efficiency of conversion and economical advantage.     

Xylitol production on sugarcane biomass hydrolysate by newly identified Candida tropicalis JA2 strain

Xylitol is a building block for a variety of chemical commodities, besides being widely used as a sugar substitute in the food and pharmaceutical industries. The aim of this work was to develop a microbial process for xylitol production using sugarcane bagasse hydrolysate as substrate. In this context, 218 non-Saccharomyces yeast strains were screened by growth on steam-exploded sugarcane bagasse hydrolysate containing a high concentration of acetic acid (8.0 g/L). Seven new Candida tropicalis strains were selected and identified, and their ability to produce xylitol on hydrolysate at low pH (4.6) under aerobic conditions was evaluated. The most efficient strain, designated C. tropicalis JA2, was capable of producing xylitol with a yield of 0.47 g/g of consumed xylose. To improve xylitol production by C. tropicalis JA2, a series of experimental procedures were employed to optimize pH and temperature conditions, as well as nutrient source, and initial xylose and inoculum concentrations. C. tropicalis JA2 was able to produce 109.5 g/L of xylitol with a yield of 0.86 g/g of consumed xylose, and with a productivity of 2.81 g·L·h, on sugarcane bagasse hydrolysate containing 8.0 g/L acetic acid and177 g/L xylose, supplemented with 2.0 g/L yeast nitrogen base and 4.0 g/L urea. Thus, it was possible to identify a new C. tropicalis strain and to optimize the xylitol production process using sugarcane bagasse hydrolysate as a substrate. The xylitol yield on biomass hydrolysate containing a high concentration of acetic acidobtained in here is among the best reported in the literature.     

Evaluation of a Malaysian soy sauce <Emphasis Type="Italic">koji</Emphasis> strain <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> NSK for γ-aminobutyric acid (GABA) production using different native sugars

In this study, a selected γ-aminobutyric acid (GABA)-rich Malaysian strain Aspergillus oryzae NSK was collected from soy sauce koji. The strain was used to explore the effect of using renewable native sugar syrup, sugarcane, nipa, and molasses as fermentable substrates for developing a novel functional GABA soy sauce. We evaluated the strain using the chosen native sugars for 7 days using shake flask fermentation at 30 °C. The results showed optimum GABA concentration was achieved using cane molasses as the fermentable substrate (354.08 mg/L), followed by sugarcane syrup (320.7 mg/L) and nipa syrup (232.07 mg/L). Cane molasses was subsequently utilized as a substrate to determine the most suitable concentration for A. oryzae NSK to enhance GABA production and was determined as 50% g/L of glucose standard cane molasses. Our findings indicate that cane molasses can be used as a GABA-rich ingredient to develop a new starter culture for A. oryzae NSK soy sauce production.     

High-temperature ethanol fermentation by immobilized coculture of Kluyveromyces marxianus and Saccharomyces cerevisiae

Suspended and immobilized cocultures of the thermotolerant yeast, Kluyveromyces marxianus DMKU 3-1042 and the mesophilic flocculent yeast, Saccharomyces cerevisiae M30 were studied for their abilities to improve production and stability of ethanol fermentation. Sugarcane juice and blackstrap molasses, at initial sugar concentrations of 220 g/L, were used as carbon sources. The results indicated that the coculture system could improve ethanol production from both sugarcane juice and blackstrap molasses when the operating temperature ranged between 33 °C and 45 °C. High temperature tolerances were achieved when the coculture was immobilized. The immobilized coculture was more effective in high-temperature ethanol fermentation than the suspended cultures. The coculture immobilized on thin-shell silk cocoon and fermented at 37 °C and 40 °C generated maximal ethanol concentrations of 81.4 and 77.3 g/L, respectively, which were 5.9-8.7% and 16.8-39.0% higher than those of the suspended cultures, respectively.     

Bioethanol production from sugar beet molasses and thick juice by free and immobilised Saccharomyces cerevisiae

The aim of this study was the investigation and comparison of the potential of sugar beet molasses and thick juice as raw materials for bioethanol production, as renewable and sustainable energy sources. Ethanol fermentation of a wide range of initial sugar concentrations (100–300 g/L) was performed using either free or immobilised Saccharomyces cerevisiae in calcium alginate beads in the absence of any added nutrients. In general, immobilised cells showed better fermentative performance, enhanced ethanol productivity, stability and cell viability compared with free cells, under the same fermentation conditions. The high concentration of non‐sugar components contained in molasses affected yeast fermentation performance and viability. Maximum ethanol concentration in fermented media of 84.6 and 109.5 g/L were obtained by immobilised cells for initial sugar concentrations of 200 and 250 g/L for molasses and thick juice, respectively. However, the highest ethanol yields of 31.7 L per 100 kg of molasses and 37.6 L per 100 kg of thick juice were obtained by immobilised cells at an initial sugar concentration of 175 g/L. In the high gravity fermentation process, thick juice resulted in a higher ethanol yield per mass of raw material compared with molasses. This study shows the advantage of immobilised yeast for the efficient production of high gravity bioethanol from thick juice, which was a more favourable raw material than molasses. © 2018 The Institute of Brewing & Distilling     

Effects of Inhibitory Environmental Factors on Growth of Oenococcus oeni CCSYU2068 for Malolactic Fermentation of Cider Production

The effects of several inhibitory factors (sulfur dioxide, pH and ethanol) on the growth of lactic acid bacteria and the subsequent malolactic fermentation (MLF) were studied by inoculation of different culture strains of Oenococcus oeni, the major lactic acid bacteria (LAB) in cider production. After comparing their organoleptic properties, three strains of Oenococcus oeni were selected from indigenous and commercial sources and their inhibitory effects on cell growth and MLF examined. The malolactic bacteria expressed variations in tolerance to the environmental conditions of pH, sulfur and ethanol concentration. Isolated from an indigenous cider production facility, O. oeni L4 had a better capacity with constant growth even when the concentration of SO₂ was 50 ppm, ethanol 10% (v/v) and pH 3.0. O. oeni L4 showed better properties for metabolizing the major acids: malic, lactic and acetic acid. The decomposition mean rate of malic acid was as high as 228.52 mg/L per day with a low acetic acid concentration of 101.78 mg/L under the stress conditions of cider production.     

红茶菌中醋酸菌和酵母菌的分离鉴定及其相互作用

采用涂布平板法分离红茶菌中的醋酸菌和酵母菌，然后将分离得到的醋酸菌和酵母菌按照一定比例分别进行共培养，比较细菌纤维素的产量差别。结果表明，从红茶菌中分离出1株醋酸菌，经鉴定为居间驹形杆菌（Komagataeibacter intermedius）；3株酵母菌，经鉴定分别为布鲁塞尔酒香酵母（Brettanomyces bruxellensis）、二孢接合酵母（Zygosaccharomyces bisporus）和核果梅奇酵母（Metschnikowia fructicola），其中布鲁塞尔酒香酵母为优势酵母。当居间驹形杆菌与布鲁塞尔酒香酵母以1∶100的比例共培养时，产生的细菌纤维素最多达4.70 g/L；当二孢接合酵母和核果梅奇酵母以相同比例分别与居间驹形杆菌共培养时产生的细菌纤维素分别为3.59 g/L（高于对照组）和1.14 g/L（低于对照组）。由此可知，布鲁塞尔酒香酵母和Z. bisporus均能够促进居间驹形杆菌产细菌纤维素，而核果梅奇酵母对居间驹形杆菌没有明显的促进作用。     

Factors affecting the production of 4-ethylphenol by the yeast Dekkera bruxellensis in enological conditions

The conversion of p-coumaric acid into 4-ethylphenol was studied in Dekkera bruxellensis ISA 1791 under defined conditions in synthetic media. The production of 4-ethylphenol occurred roughly between mid-exponential growth phase and the beginning of the stationary phase. This behaviour was observed when glucose was the only energy and carbon source, the conversion rate being close to 90%. Ethanol, as the single energy source, yielded conversion rates close to 80% while in the presence of trehalose and acetic acid conversion rates lower than 10% were obtained. The production of 4-ethylphenol was not observed when the cells were maintained in buffer solution without carbon and energy sources. The precursor of 4-ethylphenol, p-coumaric acid, was not utilized as energy and carbon source. Furthermore, it was shown that 4-vinylphenol may be used as a precursor of 4-ethylphenol in the absence of p-coumaric acid.Growth and 4-ethylphenol production were inhibited by increasing concentrations of ethanol, being fully prevented at 13% (v/v) ethanol.The cultivation of strain ISA 1791 in mixed culture with Saccharomyces cerevisiae, in synthetic medium, showed that the cell numbers of D. bruxellensis increased from 10⁴ cfu/ml to 5×10⁹ cfu/ml. Laboratory microvinifications of white and red juices inoculated with as low as 10 cfu/ml of D. bruxellensis and 10⁷ cells/ml of S. cerevisiae showed growth of D. bruxellensis to levels of about 5×10⁸ cfu/ml. In addition, 4-ethylphenol production by D. bruxellensis was observed only after complete fermentation of the grape juices.     

果蔬生防菌葡萄有孢汉逊酵母CM2糖蜜培养基的优化

以葡萄有孢汉逊酵母CM2为研究对象,细胞生物量为测定指标,利用甘蔗糖蜜作为发酵原料,对糖蜜培养基的优化进行较为全面的探讨。采用煮沸法、磷酸法、硫酸法、活性炭法、亚铁氰化钾法对糖蜜进行预处理,结果表明硫酸处理法优于其他处理方法。通过单因素试验研究糖蜜质量浓度、氮源及其添加量、初始pH值、磷酸盐、硫酸镁、氯化钠等培养基组分对CM2生长的影响;采用Plackett-Burman试验设计、最陡爬坡试验和中心组合试验设计对培养基组分进行优化,得到优化培养基组分：预处理后糖蜜78.9 g/L、酵母粉2.2 g/L、初始pH 6.0。通过验证实验获知与PDB培养基相比,优化后糖蜜培养基使CM2生物量提高了83.1%。     

Determination of Sugars in Molasses by HPLC Following Solid-Phase Extraction

Fructose, glucose, and sucrose in sugarcane molasses are determined simultaneously by high performance liquid chromatography using maltose as internal standard with refractive index detector. The mixture of the diluted samples and internal standard was purified with Sep-Pak C₁₈ solid-phase extraction and filtered through a 0.22-μm membrane before injection. The results showed that the linear ranges for fructose, glucose, and sucrose were 3.30–16.48, 1.80–9.02, and 5.94–29.70 g/L with the squared correlation coefficients (R²) being 0.9986, 0.9987, and 0.9955, respectively. The method is simple, quantified, and time-saving for determination of sugars in sugarcane molasses.     

Effect of Culture Variables on Mycelial Arachidonic acid Production by Mortierella alpina

Effect of culture conditions on biomass, lipid, and arachidonic acid production was investigated in the oleaginous fungus Mortierella alpina CBS 528.72 under shake flask conditions. Several factors have been found to affect the biomass buildup and lipogenesis in this fungus, complicated by the fact that different strains demonstrate varying optimization conditions. Growth, lipid accumulation, and arachidonic acid production in the strain investigated were influenced by media, pH, temperature, carbon source, nitrogen source, etc. The results indicated that the most effective medium for growth and arachidonic acid production was glucose yeast extract medium. The optimum pH and temperature were found to be 6.5 and 28°C, respectively. On the same weight basis, glucose was the most efficient carbon source for biomass and lipid production in this fungal strain which yielded 6.8 g/L dry biomass and 40.2% (w/w) total lipid after 7 days of cultivation. Maximum arachidonic acid (ARA) production of 40.41% achieved in rhamnose-containing media was not concomitant with higher biomass and lipid yields. Efficacy of organic carbon sources, viz, yeast extract and peptone over inorganic sources like sodium nitrate, ammonium sulfate, ammonium chloride, etc, was established in the present study. M. alpina CBS 528.72 grown in peptone acquired the highest lipid content (42.0% (w/w)). However, the ARA content (28.74%) proved to be significantly less than that grown in yeast extract (35.28%). Furthermore, it was found that the biomass and ARA production declined drastically in a medium with vegetable oils as the sole carbon source but triggered the lipogenic pathway leading to higher accumulation of total lipids. Under the ideal conditions mentioned above, the maximum biomass, total lipid, and arachidonic acid production were 6.8 g/L, 41.6%, and 35.28% total fatty acid, respectively, in shake flask system.     

白酒酿造过程中Lactobacillus panis乳酸合成关键环境因子的鉴定

Lactobacillus panis是酱香型白酒酿造过程中主要产乳酸微生物。然而,不同环境因子对L.panis乳酸合成及乳酸合成途径关键基因的表达尚未有相关研究。作者分析了温度、乳酸、乙醇及葡萄糖4种不同的发酵过程相关的典型环境因子对L.panis乳酸产量的影响。结果表明,不同环境条件能够显著调节L.panis的生长和乳酸产量,且乳酸和乙醇是酿造过程中其乳酸合成的关键影响因素。当添加10.0 g/L乳酸后,L.panis的乳酸产量最高,达到12.3 g/L;当添加体积分数4.0%乙醇后,L.panis的乳酸产量最低,仅为7.2 g/L。使用实时荧光定量PCR方法对不同条件下L.panis乳酸合成相关基因的表达进行分析,结果表明添加乳酸能够显著上调包括编码L-乳酸脱氢酶和D-乳酸脱氢酶的ldhL和ldhD在内的乳酸合成基因的表达。然而,添加乙醇会导致L.panis乳酸合成相关基因的整体显著下调。分析调控乳酸合成的关键环境因素,对于白酒酿造过程中乳酸和酿造微生物群落调控及白酒质量控制具有重要意义。     

Co-metabolism of citrate and maltose byLactobacillus brevis subsp.lindneri CB1 citrate-negative strain: effect on growth, end-products and sourdough fermentation

Growth, substrates and end-product formation of the maltose and citrate co-metabolization byLactobacillus brevis subsp.lindneri CB1 citrate-negative strain were initially studied in synthetic medium. Compared to maltose (19 g/l) fermentation, the co-metabolization of maltose (10 g/l) plus citrate (9 g/l) caused faster cell growth, increased the concentrations of lactic acid and especially of acetic acid (from 0.7 g/l to 2.9 g/l), produced succinic acid (0.5 g/l) and reduced ethanol synthesis. Highest activities of acetate kinase, the same of lactate dehydrogenase and a reduced alcohol dehydrogenase activity were detected in cytoplasmic extracts of cells growing on maltose plus citrate. The breakdown of citrate depended upon the continuous presence of maltose in the growth medium. Upon depletion of citrate, the cells continued through the normal maltose fermentation, having a diauxic metabolic curve as shown by impedance measurements. Concentrations of citrate from 3 g/l to 15 g/l led to increases of acetic acid from 1.25 g/l to 5.55 g/l. Since maltose was naturally present during sourdough fermentation, the addition of 9 g citrate per kg wheat dough enabled the co-metabolization of maltose and citrate byL. brevis subsp.lindneri CB1. Compared with traditional sourdough fermentation, faster cell growth, a higher acetic acid concentration and a reduced quotient of fermentation were obtained by co-metabolism.