Tourmaline ceramic balls stimulate growth and metabolism of three fermentation microorganisms

Effects of tourmaline ceramic balls on growth and metabolism of Saccharomyces cerevisiae, Lactobacillus acidophilus and Aspergillus oryzae were studied. Treatments with 3, 6, 9 or 12 g of tourmaline ceramic balls in a 50 ml culture showed significant stimulation of the growth of the three microorganisms. In optimal treatments with 12 g of tourmaline balls, the growth of S. cerevisiae, L. acidophilus, and A. oryzae was increased by 34, 32 and 10%, respectively. After 72 h fermentation of S. cerevisiae, total carbohydrate content in the culture medium was decreased by 65% and ethanol production was increased by 150%. Total carbohydrate content was decreased by 80% and the pH value was decreased by 0.3, as a result of organic acid production in the medium of L. acidophilus after 72 h fermentation. In the case of A. oryzae, enzyme activities of protease and amylase were increased by 90 and 31%, respectively, after 96 h fermentation. Results indicated that tourmaline stimulates initiation of growth in the early lag stage and increases production of metabolites at a later stage of fermentation. The strong stimulatory effect of tourmaline on growth, utilization of substrates and production of metabolites in the three microorganisms suggests a potential application in the fermentation industry.     

Opuntia ficus-indica cladodes as feedstock for ethanol production by Kluyveromyces marxianus and Saccharomyces cerevisiae

The feasibility of ethanol production using an enzymatic hydrolysate of pretreated cladodes of Opuntia ficus-indica (prickly pear cactus) as carbohydrate feedstock was investigated, including a comprehensive chemical analysis of the cladode biomass and the effects of limited aeration on the fermentation profiles and sugar utilization. The low xylose and negligible mannose content of the cladode biomass used in this study suggested that the hemicellulose structure of the O. ficus-indica cladode was atypical of hardwood or softwood hemicelluloses. Separate hydrolysis and fermentation and simultaneous saccharification and fermentation procedures using Kluyveromyces marxianus and Saccharomyces cerevisiae at 40 and 35 °C, respectively, gave similar ethanol yields under non-aerated conditions. In oxygen-limited cultures K. marxianus exhibited almost double the ethanol productivity compared to non-aerated cultures, although after sugar depletion utilization of the produced ethanol was evident. Ethanol concentrations of up to 19.5 and 20.6 g l^?1 were obtained with K. marxianus and S. cerevisiae, respectively, representing 66 and 70 % of the theoretical yield on total sugars in the hydrolysate. Because of the low xylan content of the cladode biomass, a yeast capable of xylose fermentation might not be a prerequisite for ethanol production. K. marxianus, therefore, has potential as an alternative to S. cerevisiae for bioethanol production. However, the relatively low concentration of fermentable sugars in the O. ficus-indica cladode hydrolysate presents a technical constraint for commercial exploitation.     

Use of Rhodopseudomonas palustris P1 stimulated growth by fermented pineapple extract to treat latex rubber sheet wastewater to obtain single cell protein

Latex rubber sheet wastewater (non sterile wastewater: RAW) was treated efficiently using a stimulated Rhodopseudomonas palustris P1 inoculum with added fermented pineapple extract (FPE) under microaerobic light conditions. Optimization of wastewater treatment conditions using a central composite design (CCD) found that a 3 % stimulated P1 inoculum with 0.9 % added FPE and a 4-day retention time (RT) were the most suitable conditions. Calculations from CCD experiments predicted that a chemical oxygen demand (COD) of 3,005 mg/L could be 98 % removed, together with 79 % of suspended solids (SS) and 72 % of total sulfide (TtS). No H₂S was detected, production costs were low and single cell protein (SCP) was a by-product. The results of the verification test had an error of only 4–8 % and confirmed removal of COD (initial COD 2,742 mg/L), SS and TtS at 94 %, 75 % and 66 %, respectively. These values were less than the best set obtained from the CCD experiment (2 % stimulated P1 inoculum, 0.75 % FPE and 4 days RT); upon repeating, this set could reduce 96 % of the COD, 78 % SS and 71 % TtS. The treated wastewater met the standard guidelines for irrigation use and no H₂S was detected. The biomass obtaining after wastewater treatment from the best set consisted mostly of R. palustris P1; the biomass of this set had 65 % protein, 3 % fat, 8 % carbohydrate, 14 % ash and 10 % moisture. The results demonstrated that an inoculum of stimulated P1 grew well in RAW supplemented with FPE and could be considered to be an appropriate technology for effectively treating wastewater, with SCP as a by-product.     

Study of a single and mixed culture for the direct bio-conversion of sorghum carbohydrates to ethanol

Fusaium oxysporum F3 alone or in mixed culture with Saccharomyces cerevisiae 2541 fermented soluble and insoluble carbohydrates of sweet sorghum stalk directly to ethanol. Both microorganisms were first grown aerobically and fermented sorghum stalk to ethanol thereafter. During fermentation, insoluble carbohydrates were hydrolysed to soluble sugars by the celluloytic system of F. oxysporum. Ethanol yields as high as 24.4 and 33.5 g/100 g dry stalks were obtained by F. oxysporum and the mixed culture respectively, representing a theoretical yield enhancement of 11.6% and 53.6% respectively. The corresponding ethanol concentrations in the fermentation medium were 4.6% and 6.4% (w/v). These results clearly demonstrated that a large portion of insoluble carbohydrate from sorghum was converted by simultaneous saccharification and fermentation to ethanol, making the process promising for bioethanol production.     

宽翅曲背蝗卵的过冷却能力与抗寒性

采用热电偶法,在室内测定了宽翅曲背蝗卵的过冷却能力及抗寒性.结果表明： 土壤含水量对滞育前卵的含水量有显著影响, 而对卵过冷却点(SCP)的影响不显著,卵含水量随着土壤含水量的升高而上升.不同发育时期卵的SCP、含水量和脂肪含量存在显著差异.随着卵的发育,其含水量从产卵当天的51.5%下降至120 d的46.8%,脂肪含量从10.5%(鲜质量)/19.0%(干质量)上升到14.5%(鲜质量)/28.9%(干质量),而SCP从-23.5 ℃下降至-30.0 ℃;卵SCP与其含水量及脂肪含量存在显著相关关系;深度滞育卵的SCP显著低于滞育前和滞育初期卵的SCP.不同低温强度和处理时间对滞育卵的存活率有显著影响.滞育卵暴露12 h的致死温度为-27.3 ℃,在-25 ℃低温处理的致死时间为22.73 d.滞育卵的SCP与致死温度相近,说明宽翅曲背蝗卵为不耐结冰类型,且SCP是衡量其抗寒性的可靠指标.     

Spheroidal carbonaceous particle record in sediments of a small reservoir

The main aims of this study were to determine whether reservoir sediments provide good temporal records of atmospherically deposited spheroidal carbonaceous particles (SCPs), and to examine their spatial distribution within the reservoir. SCPs are produced solely by fossil-fuel burning and are good indicators of the extent of industrial pollution. The site chosen for the study was Drásov Reservoir in the Czech Republic. Sediment cores were taken along two transects within the reservoir. The results suggest that wind- and inlet-induced currents have an important influence on both SCP and sediment distribution in the reservoir, and that the distribution of SCPs is different to that of sediments. The SCP records were most reliable in the down-wind area of the reservoir, and although most detailed SCP record was contained in a deep-water core near the dam, records in shallower-water cores from the down-wind side of the reservoir were also good. The correlation between SCP accumulation rates and solid emissions from local sources was very good (Spearman R=0.867, p=0.001).%     

Enhanced fermentative capacity of yeasts engineered in storage carbohydrate metabolism

During yeast biomass production, cells are grown through several batch and fed‐batch cultures on molasses. This industrial process produces several types of stresses along the process, including thermic, osmotic, starvation, and oxidative stress. It has been shown that Saccharomyces cerevisiae strains with enhanced stress resistance present enhanced fermentative capacity of yeast biomass produced. On the other hand, storage carbohydrates have been related to several types of stress resistance in S. cerevisiae. Here we have engineered industrial strains in storage carbohydrate metabolism by overexpressing the GSY2 gene, that encodes the glycogen synthase enzyme, and deleting NTH1 gene, that encodes the neutral trehalase enzyme. Industrial biomass production process simulations were performed with control and modified strains to measure cellular carbohydrates and fermentation capacity of the produced biomass. These modifications increased glycogen and trehalose levels respectively during bench‐top trials of industrial biomass propagation. We finally show that these strains display an improved fermentative capacity than its parental strain after biomass production. Modification of storage carbohydrate content increases fermentation or metabolic capacity of yeast which can be an interesting application for the food industry. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 31:20–24, 2015     

Estimating the maintenance energy and biomass concentration of Saccharomyces cerevisiae by continuous calorimetry

Continuous calorimetry has been applied to monitoring the heat evolution of Saccharomyces cerevisiae grown on d-glucose. The heat evolution, together with the energy and carbon balances, was used to evaluate the energetic efficiency of biomass, by-product biosynthesis, fermentative heat evolution as well as the maintenance energy of S. cerevisiae in ‘aerobic fermentation’ and ‘aerobic respiration’. In aerobic fermentation, under catabolite repression, the fraction of substrate energy converted to heat evolution, maintenance requirement, and biomass decreased with the increase of d-glucose concentration. The fraction of substrate energy converted to ethanol is the highest value and it could contribute up to 70% of the total substrate energy. In aerobic respiration, 43% of the total substrate energy was evolved as heat. While 50% of the total substrate energy was converted into biomass, only 7% of the total substrate energy was used for maintenance functions. The maintenance energy coefficient of S. cerevisiae was determined to be 0.427 MJ kg^?1 cell h^?1 (0.102 kcal g^?1 cell h^?1). For the first time, heat evolution together with yield-maintenance energy was used to predict biomass concentration during the fed-batch cultivation of S. cerevisiae.     

Fermentation of paddy malt mash to ethanol by mixed cultures of Saccharomyces cerevisiae and Zymomonas mobilis ZM4 with penicillin G

Traditional fermentation of paddy malt mash (containing 18.1% w/v dextrose equivalent) to paddy arrack using paddy husk as source of inoculum yielded very low level of ethanol (4.25% v/v). Use of yeast isolates obtained from paddy husk as well as a potent ethanol producer like Zymomonas mobilis ZM4 and their combinations in the fermentation revealed that a combination of an yeast isolate PH 03 (Saccharomyces cerevisiae) and Z. mobilis ZM4 produced synergistically and statistically more ethanol (10.1% v/v) than the individual and other combination of cultures. In this process, addition of penicillin G at a concentration of 20 U/ml rather than heat sterilization, helped retention of the limited amylase activity in the mash for simultaneous saccharification and fermentation over 7 d at 30°C. About 98.5% of the carbohydrate was accountable in the fermentation which yielded 86.7% of the theoretical yield of ethanol, apart from biomass and acids.     

Isolation and characterization of a Scenedesmus acutus strain to be used for bioremediation of urban wastewater

Green microalgae, due to their short growth cycle and to their ability to photosynthetically fix carbon dioxide producing an oil-rich biomass, have been proposed as an attractive alternative feedstock for the production of “second generation” biofuels. However, it has been anticipated that owing to their ability to colonize very different environments characterized by high levels of nitrogen, they can also be good candidates for bioremediation, thus integrating environmental protection with sustainable biomass production. We have isolated a strain belonging to Scenedesmus genus from urban wastewater. This isolate, Scenedesmus acutus PVUW12, was tested for its ability to grow and actively deplete eutrophicating inorganic molecules present in wastewater. In order to test its biomass productivity, the PVUW12 strain was grown in a vertical-column photobioreactor using standard growth medium obtaining a maximal productivity of 0.3?g dry weight L^?1?d. When the same strain was grown in the photobioreactor filled with wastewater collected from the final step of the local urban purifier plant containing 18.8?mg?L^?1 nitrate, we observed complete nitrogen removal coupled with a biomass production of about 0.74?g dry weight L^?1 within 3 days. After 10?days, the recovered biomass was analyzed for triglyceride content which was found to be 9.3% of the dry biomass. However, when algal cells were left for additional 10?days in static conditions the triglyceride content increased to 28.8%. These data show that this Scenedesmus strain can be used for wastewater bioremediation producing a biomass suitable for energy production.     

Lignocellulose solubilization and conversion by extremely thermophilic Caldicellulosiruptor bescii improves by maintaining metabolic activity

The extreme thermophile Caldicellulosiruptor bescii solubilizes and metabolizes the carbohydrate content of lignocellulose, a process that ultimately ceases because of biomass recalcitrance, accumulation of fermentation products, inhibition by lignin moieties, and reduction of metabolic activity. Deconstruction of low loadings of lignocellulose (5 g/L), either natural or transgenic, whether unpretreated or subjected to hydrothermal processing, by C. bescii typically results in less than 40% carbohydrate solubilization. Mild alkali pretreatment (up to 0.09 g NaOH/g biomass) improved switchgrass carbohydrate solubilization by C. bescii to over 70% compared to less than 30% for no pretreatment, with two-thirds of the carbohydrate content in the treated switchgrass converted to acetate and lactate. C. bescii grown on high loadings of unpretreated switchgrass (50 g/L) retained in a pH-controlled bioreactor slowly purged (τ = 80 hr) with growth media without a carbon source improved carbohydrate solubilization to over 40% compared to batch culture at 29%. But more significant was the doubling of solubilized carbohydrate conversion to fermentation products, which increased from 40% in batch to over 80% in the purged system, an improvement attributed to maintaining the bioreactor culture in a metabolically active state. This strategy should be considered for optimizing solubilization and conversion of lignocellulose by C. bescii and other lignocellulolytic microorganisms.     

Effects of Temperature and Relative Humidity on the Growth of and Enzyme Production by Actinomucor taiwanensis during Sufu Pehtze Preparation

The growth of and production of protease, α-amylase, α-galactosidase, and lipase by Actinomucor taiwanensis in relation to temperature and relative humidity during the preparation of sufu (Chinese cheese) pehtze were investigated. The incubation temperature, humidity, and cultivation time greatly affected the growth of and enzyme production by A. taiwanensis on tofu. It grew best at 97% humidity and 30°C. The highest yields of protease (112 U/g of dry tofu) and lipase (1,448 U/g of dry tofu) were found after 60 h of incubation at 97% humidity and 25°C. On the other hand, the highest yield of α-amylase (1,949 U/g of dry tofu) was observed after 48 h of incubation at 96 to 97% humidity and 30°C, and the highest amount of α-galactosidase (387 U/g of dry tofu) was observed at 35°C and 96% humidity after 60 h of growth. The results suggest that the temperature and humidity should be controlled at 25 to 30°C and around 97%, respectively, during the commercial preparation of sufu pehtze for better growth of and production of enzymes by A. taiwanensis.     

Construction of a Xylan-Fermenting Yeast Strain through Codisplay of Xylanolytic Enzymes on the Surface of Xylose-Utilizing Saccharomyces cerevisiae Cells

Hemicellulose is one of the major forms of biomass in lignocellulose, and its essential component is xylan. We used a cell surface engineering system based on α-agglutinin to construct a Saccharomyces cerevisiae yeast strain codisplaying two types of xylan-degrading enzymes, namely, xylanase II (XYNII) from Trichoderma reesei QM9414 and β-xylosidase (XylA) from Aspergillus oryzae NiaD300, on the cell surface. In a high-performance liquid chromatography analysis, xylose was detected as the main product of the yeast strain codisplaying XYNII and XylA, while xylobiose and xylotriose were detected as the main products of a yeast strain displaying XYNII on the cell surface. These results indicate that xylan is sequentially hydrolyzed to xylose by the codisplayed XYNII and XylA. In a further step toward achieving the simultaneous saccharification and fermentation of xylan, a xylan-utilizing S. cerevisiae strain was constructed by codisplaying XYNII and XylA and introducing genes for xylose utilization, namely, those encoding xylose reductase and xylitol dehydrogenase from Pichia stipitis and xylulokinase from S. cerevisiae. After 62 h of fermentation, 7.1 g of ethanol per liter was directly produced from birchwood xylan, and the yield in terms of grams of ethanol per gram of carbohydrate consumed was 0.30 g/g. These results demonstrate that the direct conversion of xylan to ethanol is accomplished by the xylan-utilizing S. cerevisiae strain.     

Industrial yeast strain engineered to ferment ethanol from lignocellulosic biomass

In this study an industrial Saccharomyces cerevisiae yeast strain capable of fermenting ethanol from pretreated lignocellulosic material was engineered. Genes encoding cellulases (endoglucanase, exoglucanase and β-glucosidase) were integrated into the chromosomal ribosomal DNA and delta regions of a derivative of the K1-V1116 wine yeast strain. The engineered cellulolytic yeast produces ethanol in one step through simultaneous saccharification and fermentation of pretreated biomass without the addition of exogenously produced enzymes. When ethanol fermentation was performed with 10% dry weight of pretreated corn stover, the recombinant strain fermented 63% of the cellulose in 96 h and the ethanol titer reached 2.6% v/v. These results demonstrate that cellulolytic S. cerevisiae strains can be used as a platform for developing an economical advanced biofuel process.     

Expression and Secretion of Defined Cutinase Variants by Aspergillus awamori

Several cutinase variants derived by molecular modelling and site-directed mutagenesis of a cutinase gene from Fusarium solani pisi are poorly secreted by Saccharomyces cerevisiae. The majority of these variants are successfully produced by the filamentous fungus Aspergillus awamori. However, the L51S and T179Y mutations caused reductions in the levels of extracellular production of two cutinase variants by A. awamori. Metabolic labelling studies were performed to analyze the bottleneck in enzyme production by the fungus in detail. These studies showed that because of the single L51S substitution, rapid extracellular degradation of cutinase occurred. The T179Y substitution did not result in enhanced sensitivity towards extracellular proteases. Presumably, the delay in the extracellular accumulation of this cutinase variant is caused by the enhanced hydrophobicity of the molecule. Overexpression of the A. awamori gene encoding the chaperone BiP in the cutinase-producing A. awamori strains had no significant effect on the secretion efficiency of the cutinases. A cutinase variant with the amino acid changes G28A, A85F, V184I, A185L, and L189F that was known to aggregate in the endoplasmic reticulum of S. cerevisiae, resulting in low extracellular protein levels, was successfully produced by A. awamori. An initial bottleneck in secretion occurred before or during translocation into the endoplasmic reticulum but was rapidly overcome by the fungus.     

大豆豆乳和豆腐产量、品质及有关加工性状的遗传变异

采用全国各地的261个大豆品种为材料,研究豆乳和豆腐产量、品质及有关加工性状的遗传变异.结果表明豆乳和豆腐加工过程中每100g干籽粒平均生产干豆乳71.92g,生产干豆腐51.80g,损失豆渣干物质25.76g,损失乳清干物质20.12g.干豆乳蛋白质、脂肪和总糖的含量分别为51.85%、22.55%和18.42%,干豆腐蛋白质、脂肪和总糖的含量分别为46.22%、24.58%和19.36%.豆乳和豆腐产量、品质及有关加工性状在品种间的差异均达到极显著水平,变异系数都较大,从中筛选出一批优异种质.     

Kinetics of biodegradation of free gossypol by Candida tropicalis in solid-state fermentation

In the present work experiments were carried out to study the effect of free gossypol on the growth of Candida tropicalis ZAU-1, evaluate its ability in biodegrading free gossypol, analyze the time course of solid-state fermentation, and model the microbial growth by determining the kinetics of dry matter weight loss, total carbohydrate concentration and the free gossypol content during solid-state fermentation. Results showed that the biomass in inorganic salts glucose medium were unaffected by free gossypol at 500 and 1000 mg/l levels, compared with the control group (p > 0.05); degradation of free gossypol reached 95.12% and 94.12%, respectively. A logistic equation (R² = 0.9922), describing the growth model of C. tropicalis ZAU-1 was obtained, with the maximum values of u_m and X_m at 0.0970 h⁻¹ and 21.8631% of dry matter weight loss, respectively. A good-fit curvilinear regression model was achieved to describe the change pattern of total carbohydrate concentration (R² = 0.9910), and the biodegradation pattern of free gossypol (R² = 0.9825). These models could be used to predict the fermentation course by C. tropicalis ZAU-1 under solid-state fermentation.     

Xylanase and pectinase production by Aspergillus awamori on grape pomace in solid state fermentation

The feasibility of using grape pomace for the production of xylanase and exo-polygalacturonase by Aspergillus awamori in solid state fermentation has been evaluated. Solid state fermentation experiments indicated that the particle size did not influence the enzyme production. The addition of extra carbon sources and the initial moisture content of the grape pomace were found to have a marked influence on the enzymes yields. Xylanase and exo-PG activities were high at 65% (w/w) initial moisture content and glucose supplementation.     

Effect of nickel oxide nanoparticles on bioethanol production: Process optimization,kinetic and metabolic studies

The present study optimized ethanol yield using nickel oxide (NiO) nanoparticles (NPs) as a biocatalyst. Additionally, Saccharomyces cerevisiae BY4743 cell growth and the bioethanol production kinetics were assessed. The Response Surface Methodology (RSM) model showed a coefficient of determination (R²) value of 0.93. The optimized process gave a biomass concentration and ethanol yield of 2.04 g/L and 0.26 g/g (1.03 and 1.19-fold increment compared to the control experiment), respectively. The process kinetic data showed that the inclusion of NiO NPs improved the affinity of S. cerevisiae BY4743 to glucose consumption, carbohydrate and protein accumulation. A significant reduction in volatile fatty acid (VFA) was observed in the presence of NiO NPs. The application of nano biocatalyst in simultaneous saccharification and fermentation of potato peel waste, meaningfully enhanced bioethanol production (>65 %). The study provided major insights into the use of NiO NPs to enhance the bioprocess of ethanol production.