三江平原湿地开垦对土壤氨基糖积累特征的影响

微生物残体在土壤有机质的形成和稳定过程中发挥着重要作用,但湿地开垦对土壤微生物残体积累特征的影响尚不清楚。本研究以三江平原小叶章湿地为对象,采集原始自然湿地和开垦改种豆科作物后不同耕作年限(5年、10年和25年)的土壤,以氨基糖为微生物残体的标识物,探讨湿地开垦对土壤微生物残体积累特征的影响。结果表明: 自然湿地开垦为农田后显著降低了土壤中氨基糖的含量,且随着开垦年限的增加,氨基糖的损失比例也增加。与自然湿地相比,开垦25年后土壤中的氨基葡萄糖、氨基半乳糖和胞壁酸含量分别下降38.0%、38.1%和35.9%,且在开垦最初5年中细菌来源的胞壁酸下降速率(25.8%)远高于真菌来源的氨基葡萄糖(14.9%),说明短期内湿地开垦对细菌的影响较真菌更加迅速。湿地开垦为农田5、15和25年后,土壤氨基糖总量分别下降21.1%、34.0%和38.0%;同时,氨基糖总量占土壤有机质的比例也受到湿地开垦的显著影响,由自然湿地中的4.8%降至开垦25年后的4.4%。这说明长期湿地开垦加速了土壤有机质中微生物来源有机组分的分解转化,进而改变土壤有机质的组成。这些变化将影响湿地生态系统中土壤有机质的长期稳定和功能演变。     

Effects of faba bean,blue lupin and rapeseed meal supplementation on nitrogen digestion and utilization of dairy cows fed grass silage-based diets

There is increasing interest in using locally produced protein supplements in dairy cow feeding. The objective of this experiment was to compare rapeseed meal (RSM), faba beans (FBs) and blue lupin seeds (BL) at isonitrogenous amounts as supplements of grass silage and cereal based diets. A control diet (CON) without protein supplement was included in the experiment. Four lactating Nordic Red cows were used in a 4 × 4 Latin Square design with four 21 d periods. The milk production increased with protein supplementation but when expressed as energy corrected milk, the response disappeared due to substantially higher milk fat concentration with CON compared to protein supplemented diets. Milk protein output increased by 8.5, 4.4 and 2.7% when RSM, FB and BL were compared to CON. The main changes in rumen fermentation were the higher propionate and lower butyrate proportion of total rumen volatile fatty acids when the protein supplemented diets were compared to CON. Protein supplementation also clearly increased the ruminal ammonia N concentration. Protein supplementation improved diet organic matter and NDF digestibility but efficiency of microbial protein synthesis per kg organic matter truly digested was not affected. Flow of microbial N was greater when FB compared to BL was fed. All protein supplements decreased the efficiency of nitrogen use in milk production. The marginal efficiency (amount of additional feed protein captured in milk protein) was 0.110, 0.062 and 0.045 for RSM, FB and BL, respectively. The current study supports the evidence that RSM is a good protein supplement for dairy cows, and this effect was at least partly mediated by the lower rumen degradability of RSM protein compared to FB and BL. The relatively small production responses to protein supplementation with simultaneous decrease in nitrogen use efficiency in milk production suggest that economic and environmental consequences of protein feeding need to be carefully considered.     

The Degree and Length of O-Glycosylation of Recombinant Proteins Produced in Pichia pastoris Depends on the Nature of the Protein and the Process Type

The methylotrophic yeast Pichia pastoris is known as an efficient host for the production of heterologous proteins. While N-linked protein glycosylation is well characterized in P. pastoris there is less knowledge of the patterns of O-glycosylation. O-glycans produced by P. pastoris consist of short linear mannose chains, which in the case of recombinant biopharmaceuticals can trigger an immune response in humans. This study aims to reveal the influence of different cultivation strategies on O-mannosylation profiles in P. pastoris. Sixteen different model proteins, produced by different P. pastoris strains, are analyzed for their O-glycosylation profile. Based on the obtained data, human serum albumin (HSA) is chosen to be produced in fast and slow growth fed batch fermentations by using common promoters, P_GAP and P_AOX1. After purification and protein digestion, glycopeptides are analyzed by LC/ESI-MS. In the samples expressed with P_GAP it is found that the degree of glycosylation is slightly higher when a slow growth rate is used, regardless of the efficiency of the producing strain. The highest glycosylation intensity is observed in HSA produced with P_AOX1. The results indicate that the O-glycosylation level is markedly higher when the protein is produced in a methanol-based expression system.     

优良菌种发酵葡萄酒优化条件的探讨

以诱变耐低温果酒酵母菌种YU2.28和产香酵母S15.3为发酵菌株,进行了葡萄酒发酵条件优化的试验研究.探讨了菌种生长温度、通氧量等因素,通过对菌种的生长情况和发酵醪液中总酯含量的变化分析,确定了自选酵母酿制葡萄酒的最佳技术参数,并对优化条件下发酵得到的葡萄酒进行GC/MS分析.结果显示：YU2.28和S15.3以1：3比例的混合发酵,接种量3%,调节醪液pH值为4.0,SO2添加量40 mg/L,发酵温度20℃,主发酵6 d内控制以230r/min的摇床转速进行摇瓶发酵,并进行9 h（每天1.5 h）供氧处理,后发酵30 d,酿造出的葡萄酒品质较佳,具有酒体丰盈,酒液澄清透亮,香气醇和的特征.成品酒香气成分共检测出醇类9种,酯类8种,酸类6种和少量的醛类、酮类等成分.     

A Review of: “Progress in Separation and Purification Vol. 3, E. S. Perry and C. J,van Oss,eds., Willy/Intersciencc,New York, 1970; xi + 316 pares; hard cover; 515.95”

The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Pleurotus geesteranus 5 ^# were determined using an orthogonal matrix method. The optimal defined medium (per liter) was 60.0 g maltose, 5.0 g tryptone, 1 mM NaCl, 5 mM KH₂PO₄, and initial pH 6.0 at 28 °C. In the optimal culture medium, the maximum EPS production was 16.97 g/L in a shake flask. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography (SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The approximate weight-average molar masses of the Fr-I and Fr-II of EPS were determined to be 3.263 × 10⁴ and 5.738 × 10³ g/mol, respectively. The low values of polydispersity ratio (1.176 and 1.124 for Fr-I and Fr-II, respectively) of EPSs mean that these EPS molecules exist much less dispersed in aqueous solution without forming large aggregates. Furthermore, the experiments in vitro indicated that P. geesteranus 5^# EPS exhibit high antitumor and antioxidative effects.     

STATISTICAL APPROACH FOR THE ENHANCED PRODUCTION OF COLD-ACTIVE β-GALACTOSIDASE FROM Thalassospira frigidphilosprofundus: A NOVEL MARINE PSYCHROPHILE FROM DEEP WATERS OF BAY OF BENGAL

In the present investigation Thalassospira frigidphilosprofundus, a novel species from the deep waters of the Bay of Bengal, was explored for the production of cold-active β-galactosidase by submerged fermentation using marine broth medium as the basal medium. Effects of various medium constituents, namely, carbon, nitrogen source, pH, and temperature, were investigated using a conventional one-factor-at-a-time method. It was found that lactose, yeast extract, and bactopeptones are the most influential components for β-galactosidase production. Under optimal conditions, the production of β-galactosidase was found to be 3,864 U/mL at 20 ± 2°C, pH 6.5 ± 0.2, after 48 hr of incubation. β-Galactosidase production was further optimized by the Taguchi orthogonal array design of experiments and the central composite rotatable design (CCRD) of response surface methodology. Under optimal experimental conditions the cold-active β-galactosidase enzyme production from Thalassospira frigidphilosprofundus was enhanced from 3,864 U/mL to 10,657 U/mL, which is almost three times higher than the cold-active β-galactosidase production from the well-reported psychrophile Pseudoalteromonas haloplanktis.     

An improved Method for Isolation of Rat Testis Golgi Apparatus H. H. Mollenhauer

The preparation of Golgi apparatus fractions from rat testis germ cells free from contamination by residual body fragments was accomplished by the use of the Yeda press as the homogenization device. The Golgi apparatus thus prepared retained excellent stuctural intactness. This method also allows for isolation of Golgi apparatus from single cell suspensions.     

EVALUATION OF BIOETHANOL PRODUCTION FROM CAROB PODS BY Zymomonas mobilis AND Saccharomyces cerevisiae IN SOLID SUBMERGED FERMENTATION

Bioethanol production from carob pods has attracted many researchers due to its high sugar content. Both Zymomonas mobilis and Saccharomyces cerevisiae have been used previously for this purpose in submerged and solid-state fermentation. Since extraction of sugars from the carob pod particles is a costly process, solid-state and solid submerged fermentations, which do not require the sugar extraction step, may be economical processes for bioethanol production. The aim of this study is to evaluate the bioethanol production in solid submerged fermentation from carob pods. The maximum ethanol production of 0.42 g g^?1 initial sugar was obtained for Z. mobilis at 30°C, initial pH 5.3, and inoculum size of 5% v/v, 9 g carob powder per 50 mL of culture media, agitation rate 0 rpm, and fermentation time of 40 hr. The maximum ethanol production for S. cerevisiae was 0.40 g g^?1 initial sugar under the same condition. The results obtained in this research are comparable to those of Z. mobilis and S. cerevisiae performance in other culture mediums from various agricultural sources. Accordingly, solid submerged fermentation has a potential to be an economical process for bioethanol production from carob pods.     

EFFECT OF FERMENTATION PARAMETERS ON BIO-ALCOHOLS PRODUCTION FROM GLYCEROL USING IMMOBILIZED Clostridium pasteurianum: AN OPTIMIZATION STUDY

This article addresses the issue of effect of fermentation parameters for conversion of glycerol (in both pure and crude form) into three value-added products, namely, ethanol, butanol, and 1,3-propanediol (1,3-PDO), by immobilized Clostridium pasteurianum and thereby addresses the statistical optimization of this process. The analysis of effect of different process parameters such as agitation rate, fermentation temperature, medium pH, and initial glycerol concentration indicated that medium pH was the most critical factor for total alcohols production in case of pure glycerol as fermentation substrate. On the other hand, initial glycerol concentration was the most significant factor for fermentation with crude glycerol. An interesting observation was that the optimized set of fermentation parameters was found to be independent of the type of glycerol (either pure or crude) used. At optimum conditions of agitation rate (200 rpm), initial glycerol concentration (25 g/L), fermentation temperature (30°C), and medium pH (7.0), the total alcohols production was almost equal in anaerobic shake flasks and 2-L bioreactor. This essentially means that at optimum process parameters, the scale of operation does not affect the output of the process. The immobilized cells could be reused for multiple cycles for both pure and crude glycerol fermentation.     

Microbial interactions associated with secondary cucumber fermentation

Aims

To evaluate the interaction between selected yeasts and bacteria and associate their metabolic activity with secondary cucumber fermentation.

Methods and Results

Selected yeast and bacteria, isolated from cucumber secondary fermentations, were inoculated as single and mixed cultures in a cucumber juice model system. Our results confirmed that during storage of fermented cucumbers and in the presence of oxygen, spoilage yeasts are able to grow and utilize the lactic and acetic acids present in the medium, which results in increased brine pH and the chemical reduction in the environment. These conditions favour opportunistic bacteria that continue the degradation of lactic acid. Lactobacillus buchneri, Clostridium bifermentans and Enterobacter cloacae were able to produce acetic, butyric and propionic acids, respectively, when inoculated in the experimental medium at pH 4·6. Yeast and bacteria interactions favoured the survival of Cl. bifermentans and E. cloacae at the acidic pH typical of fermented cucumbers (3·2), but only E. cloacae was able to produce a secondary product.

Conclusions

The methodology used in this study confirmed that a complex microbiota is responsible for the changes observed during fermented cucumber secondary fermentation and that certain microbial interactions may be essential for the production of propionic and butyric acids.

Significance and Impact of the Study

Understanding the dynamics of the development of secondary cucumber fermentation aids in the identification of strategies to prevent its occurrence and economic losses for the pickling industry.