The role of Chironomidae in energy flow of a lotic ecosystem

Chironomid secondary production was estimated on a species-specific basis for 14 dominant taxa in a third-order woodland stream. Results from this study were used to provide an expalanation for the common observation that benthos secondary production in streams is insufficient to account for levels of fish production,i.e., the ALLEN paradox. Annual chironomid secondary production was 29.7 g dry mass m^–2 and accounted for 80% of the total aquatic insect secondary production. A contribution by chironomids this high has not been reported previously from similar streams and indicates that chironomids are an energetically important group available for fish consumption. Most studies examining chironomid secondary production group all taxa at the family level and calculate secondary production for the entire family using the size-frequency method. This approach violates assumptions of the size-frequency method and will result in inaccurate and unpredictable estimates of chironomid secondary production. The species-specific approach to estimate chironomid production used in this study, combined with non-chironomid production, yielded a benthos annual production rate that exceeded consumption necessary to support fish production.     

Prospects for microbial biodiesel production

As the demand for biofuels for transportation is increasing, it is necessary to develop technologies that will allow for low-cost production of biodiesel. Conventional biodiesel is mainly produced from vegetable oil by chemical transesterification. This production, however, has relatively low land-yield and is competing for agricultural land that can be used for food production. Therefore, there is an increasing interest in developing microbial fermentation processes for production of biodiesel as this will allow for the use of a wide range of raw-materials, including sugar cane, corn, and biomass. Production of biodiesel by microbial fermentation can be divided into two different approaches, (1) indirect biodiesel production from oleaginous microbes by in vitro transesterification, and (2) direct biodiesel production from redesigned cell factories. This work reviews both microbial approaches for renewable biodiesel production and evaluates the existing challenges in these two strategies.     

Microbial production of organic acids: expanding the markets

Microbial production of organic acids is a promising approach for obtaining building-block chemicals from renewable carbon sources. Although some acids have been produced for some time and in-depth knowledge of these microbial production processes has been gained, further microbial production processes seem to be feasible, but large-scale production has not yet been possible. Citric, lactic and succinic acid production exemplify three processes in different stages of industrial development. Although the questions being addressed by current research on these processes are diverging, a comparison is helpful for understanding microbial organic acid production in general. In this article, through analysis of the current advances in production of these acids, we present guidelines for future developments in this fast-moving field.     

Spatial distribution of nectar production in a natural Echium vulgare population: Implications for pollinator behaviour

The distribution of trait values in many populations is not homogenous but creates a mosaic of patches. This may lead to differences in selection on the patch level compared to selection on the population level. As an example we investigated the spatial distribution of nectar production and its effects on pollinator behaviour in a natural population of Echium vulgare. Nectar production per flower, number of flowers and total nectar production showed a hierarchy and spatial aggregation as expressed by Gini coefficients and significant Moran's I values. Plants in patches of high nectar production received significantly more pollinator visits and had a significant emanating effect on pollinator visits of neighbouring plants. The same was true for plants in patches with high number of flowers. To disentangle these effects a path analysis was applied, which suggested that the direct effect of nectar production per flower although present, seems to be small compared to the effect of the number of flowers. Nectar production per flower affected pollinator visits mainly indirectly by way of total nectar production, which includes the effect of number of flowers. Assuming a minor pollinator-mediated selection for number of flowers, pollinator-mediated selection for total nectar production equals that for nectar production per flower. If so, the observed spatial structure of nectar production and its emanating effect on pollinator behaviour is of importance for natural selection. Plants of low nectar production occurring close to patches of plants with high nectar production benefited from the enhanced pollinator service of their neighbours while saving costs of increased nectar production. Consequently, plants with low nectar production may have a selective advantage at patch level while plants with high nectar production may have a selective advantage at population level. Results presented stress the importance of small-scale patterns for ecological relationships and evolutionary change.     

Developments and perspectives of photobioreactors for biofuel production

The production of biofuels from microalgae requires efficient photobioreactors in order to meet the tight constraints of energy efficiency and economic profitability. Current cultivation systems are designed for high-value products rather than for mass production of cheap energy carriers. Future bioreactors will imply innovative solutions in terms of energy efficiency, light and gas transfer or attainable biomass concentration to lower the energy demand and cut down production costs. A new generation of highly developed reactor designs demonstrates the enormous potential of photobioreactors. However, a net energy production with microalgae remains challenging. Therefore, it is essential to review all aspects and production steps for optimization potential. This includes a custom process design according to production organism, desired product and production site. Moreover, the potential of microalgae to synthesize valuable products additionally to the energetic use can be integrated into a production concept as well as waste streams for carbon supply or temperature control.     

High-cell-density culture strategies for polyhydroxyalkanoate production: a review

This article gives an overview of high-cell-density cultures for polyhydroxyalkanoate (PHA) production and their modes of operation for increasing productivity. High cell densities are very important in PHA production mainly because this polymer is an intracellular product accumulated in various microorganisms, so a high cellular content is needed for the polymer production. This review describes relevant results from fed-batch, repeated batch, and continuous modes of operation without and with cell recycle for the production of these polymers by microorganisms. Finally, recombinant microorganisms for PHA production, as well future directions for PHA production, are discussed.     

Fedbatch operation using Clostridium acetobutylicum suspension culture as biocatalyst for enhancing hydrogen production

We demonstrated the feasibility of fedbatch operation using Clostridium acetobutylicum suspension culture as a biocatalyst for the continuous production of hydrogen. The optimum operating pH and temperature of the current cultivation system for hydrogen production were pH 6.0 and 37 degrees C, respectively. The volumetric loading of the bioreactor for hydrogen production can be as high as 650 mmol hydrogen/L culture with a yield at approximately 2.0 mol hydrogen/mol glucose. Acetate and butyrate made up approximately 80% of the total metabolites. The inhibitory effect from the two metabolites on the hydrogen production process was investigated. Butyrate at a concentration higher than 13 g/L significantly inhibited not only cell growth but also hydrogen production (i.e., specific hydrogen production rate). Acetate appears to be less toxic than butyrate to the hydrogen production process. While significantly inhibiting cell growth, acetate hardly affected hydrogen production. Finally, the factors limiting cultivation performance were discussed and possible strategies for enhancing the production of hydrogen were proposed.     

Production of Lysergic Acid Derivatives in Submerged Culture: IV. Inorganic Nutrition Studies with Claviceps paspali

The inorganic requirements for growth and alkaloid production by submerged cultures of a lysergic acid alkaloid-producing isolate of Claviceps paspali were determined in a defined medium. The requirement for peak growth was essentially the same as the requirement for maximal alkaloid production in the case of potassium and magnesium. With phosphorus, however, maximal growth was reached at lower levels than those required for maximal alkaloid production. Sulfur was required in smaller amounts for peak alkaloid production than for maximal growth. In the case of iron and zinc, the requirement for maximal alkaloid production was greater than for growth. Manganese and copper could be sufficiently depleted to demonstrate their essentiality for alkaloid production, but their requirements for growth could not be demonstrated.     

Biodiesel production with special emphasis on lipase-catalyzed transesterification

The production of biodiesel by transesterification employing acid or base catalyst has been industrially accepted for its high conversion and reaction rates. Downstream processing costs and environmental problems associated with biodiesel production and byproducts recovery have led to the search for alternative production methods. Recently, enzymatic transesterification involving lipases has attracted attention for biodiesel production as it produces high purity product and enables easy separation from the byproduct, glycerol. The use of immobilized lipases and immobilized whole cells may lower the overall cost, while presenting less downstream processing problems, to biodiesel production. The present review gives an overview on biodiesel production technology and analyzes the factors/methods of enzymatic approach reported in the literature and also suggests suitable method on the basis of evidence for industrial production of biodiesel.     

碳素和氮素对Coriolus versicolor胞外酶分泌的影响

采用单因子相互比较法研究了不同碳素和氮素对彩绒革盖菌胞外漆酶,愈创木酚氧化酶,多酚氧化酶,锰过氧化物酶等木素降解酶分泌的影响,结果淀粉作碳源,干酪素作氮源有利于漆酶的分泌,麦芽粉作碳源,酵母膏作氮源有利于愈创木酚氧化酶和多酚氧化酶的分泌,淀粉作碳源,玉米粉作氮源有利于锰过氧化物酶的分泌。     

Production of Thermostable Alkaline Proteases by Thermophilic Streptomyces

Conditions for the production of thermostable proteases (alkaline proteinase and carboxypeptidase) by a thermophilic streptomycete (Streptomyces rectus var. proteolyticus) were investigated in 20-liter volumes. Proteinase production was affected by the concentration of defatted soybean powder, its optimum being 1.2% in medium containing 2.0% soluble starch. Relatively high concentration of phosphate (0.3 to 0.4% K(2)HPO(4)) was needed for the maximum enzyme production. A large inoculum size (5 to 10%) was favorable, but the inoculum age did not significantly influence the production. The yield increase of 20 to 30% was obtained by feeding of medium during fermentation. The optimal temperature for proteinase production was 50 C, at which the maximal rate of production was 66.2 proteinase units per ml per hr, whereas at 40 C it was 9.0. Production at 50 C reached the maximum within 12 to 16 hr. The optimal agitation rate was different for the production of proteinase and carboxypeptidase, 400 rev/min for the former and 500 rev/min for the latter. The optimal aeration for proteinase production was 20 to 30 liters/min at 400 rev/min, whereas carboxypeptidase production was not markedly affected by aeration rate. The possibility that carboxypeptidase production was correlated with the shear of mycelium was discussed.     

Composition of culture medium is more important than co-culture with hepatic non-parenchymal cells in albumin production activity of primary rat hepatocytes,and the effect was enhanced by hepatocytes spheroid culture in collagen gel

Co-culture of primary rat hepatocytes with hepatic non-parenchymal cells or sinusoidal endothelial cells for albumin production activity as an index of liver-specific function was studied. The co-cultures were effective for the expression and maintenance of albumin production activity. However, the co-culture effect was not observed when we used a suitable culture medium, which had already been reported to be sufficient for albumin production activity. Albumin production of dispersed cells in collagen gel culture was higher than that of spheroid culture. In addition, albumin production of spheroids in collagen gel culture was higher than that of spheroid culture and dispersed cell collagen gel culture with a suitable culture medium. We found that culture medium composition was more important than co-culture for expression and maintenance of albumin production. Furthermore, we found that cell–cell interaction was effective for the expression of albumin production, but heterotypic cell–cell interaction was not necessary.     

Effects of the principal nutrients on lovastatin production by Monascus pilosus

Lovastatin production is dependent on the substrates provided. We investigated how several carbon and nitrogen sources in the medium affect lovastatin production by Monascus pilosus. M. pilosus required a suitable concentration of organic nitrogen peptone for high lovastatin production. As sole carbon source with peptone, although glucose strongly repressed lovastatin production, maltose was responsible for high production. Interestingly, glycerol combined with maltose enhanced lovastatin production, up to 444 mg/l in the most effective case. Moreover, an isolated mutant, in which glucose repression might be relieved, easily produced the highest level of lovastatin, 725 mg/l on glucose-glycerol-peptone medium. These observations indicate that lovastatin production by M. pilosus is regulated by strict glucose repression and that an appropriate release from this repression by optimizing medium composition and/or by a mutation(s) is required for high lovastatin production.     

Bioreactor and process design for biohydrogen production

Biohydrogen is regarded as an attractive future clean energy carrier due to its high energy content and environmental-friendly conversion. It has the potential for renewable biofuel to replace current hydrogen production which rely heavily on fossil fuels. While biohydrogen production is still in the early stage of development, there have been a variety of laboratory- and pilot-scale systems developed with promising potential. This work presents a review of advances in bioreactor and bioprocess design for biohydrogen production. The state-of-the art of biohydrogen production is discussed emphasizing on production pathways, factors affecting biohydrogen production, as well as bioreactor configuration and operation. Challenges and prospects of biohydrogen production are also outlined.     

氨水流加用于粪产碱杆菌热凝胶发酵

热凝胶是粪产碱杆菌(Alcaligenes faecalis)在氮源限制条件下生成的水不溶性胞外多糖,分泌到胞外后就附着在菌体外壁,因此在细胞生长期提高生物量对促进热凝胶合成有重要意义。热凝胶分批发酵时, 起始NH4Cl浓度提高到3.6 g/L时能促进菌体生长和热凝胶合成,但是过量NH4Cl会抑制热凝胶合成,且生物量提高不是很明显。为了进一步提高菌体浓度, 在菌体生长期, 氨水取代NaOH溶液进行流加控制pH为7.0, 随后又用2 mol/L NaOH控制pH 5.6。实验表明, 氨水流加使菌体浓度大大提高,流加24 h使菌体浓度达到18.8 g/L。但是菌体浓度过高也会抑制热凝胶的合成,在氨水流加14 h时,菌体浓度在11.9 g/L左右, 热凝胶产量最高（72 g/L）。     

Genome-wide identification of the targets for genetic manipulation to improve l-lactate production by Saccharomyces cerevisiae by using a single-gene deletion strain collection

To identify genome-wide targets for gene manipulation for increasing l-lactate production in recombinant Saccharomyces cerevisiae strains, we transformed all available single-gene deletion strains of S. cerevisiae with a plasmid carrying the human l-lactate dehydrogenase gene, and examined l-lactate production in the obtained transformants. The thresholds of increased or decreased l-lactate production were determined based on l-lactate production by the standard strain in repetitive experiments. l-lactate production data for 4802 deletion strains were obtained, and deletion strains with increased or decreased l-lactate production were identified. Functional category analysis of genes whose deletion increased l-lactate production revealed that ribosome biogenesis-related genes were overrepresented. Most deletion strains for genes related to ribosome biogenesis exhibited increased l-lactate production in 200-ml batch cultures. We deleted the genes related to ribosome biogenesis in a recombinant strain of S. cerevisiae with a genetic background different from that of the above deletion strains, and examined the effect of target gene deletion on l-lactate production. We observed that deletion of genes related to ribosome biogenesis leads to increased l-lactate production by recombinant S. cerevisiae strains, and the single-gene deletion strain collection could be utilized in identifying target genes for improving l-lactate production in S. cerevisiae recombinant strains.     

地鼠繁殖方式的改进与规模化生产

目的：探索SPF地鼠在屏障系统内的配种繁殖方式是否适合目前地鼠大规模生产,满足乙脑减毒活疫苗生产所需动物。方法：采取短期同居配种的繁殖方式进行试验和大规模生产。结果：短期同居配种的繁殖方式与人工刺激配种的繁殖方式相比具有仔鼠成活率高、受孕率高、单产高、利用率高的特点。结论：地鼠短期同居配种的繁殖方式适合在屏障系统内操作和大规模生产。     

Perspectives for biotechnological production of biodiesel and impacts

In recent years, biological ways for biodiesel production have drawn an increasing attention and compared to chemical approaches, lipase-mediated alcoholysis for biodiesel production has many advantages. Currently, there are extensive reports about enzyme-mediated alcoholysis for biodiesel production, and based on the application forms of biocatalyst, the related research can be classified into immobilized lipase, whole cell catalyst, and liquid lipase-mediated alcoholysis for biodiesel production, respectively. This mini-review is focusing on the study of the aforementioned three forms of biocatalyst for biodiesel production, as well as its impacts and prospects.     

The application of a generic feedstock from wheat for microbial fermentations

The feasibility of a generic fermentation feedstock produced from wheat flour has been confirmed in several fermentations of yeasts, bacterium, and filamentous fungus for the production of commodity chemicals. Saccharomyces cerevisiae was incubated for the observation of yeast growth and ethanol production, Pichia farinosa for glycerol production, Monascus purpureus for fungal growth and pigment production, and Lactobacillus bulgaricus for bacteria growth and lactic acid production. The results confirmed that the feedstock contained no inhibitory components to the strains tested. Similar or higher metabolite yields were obtained in comparison with other studies carried in commonly used media.     

Lipoteichoic acid-induced nitric oxide production depends on the activation of platelet-activating factor receptor and Jak2

NO production by macrophages in response to lipoteichoic acid (LTA) and a synthetic lipopeptide (Pam3CSK4) was investigated. LTA and Pam3CSK4 induced the production of both TNF-alpha and NO. Inhibitors of platelet-activating factor receptor (PAFR) blocked LTA- or Pam3CSK4-induced production of NO but not TNF-alpha. Jak2 tyrosine kinase inhibition blocked LTA-induced production of NO but not TNF-alpha. PAFR inhibition blocked phosphorylation of Jak2 and STAT1, a key factor for expressing inducible NO synthase. In addition, LTA did not induce IFN-beta expression, and p38 mitogen-activated protein serine kinase was necessary for LTA-induced NO production but not for TNF-alpha production. These findings suggest that Gram-positive bacteria induce NO production using a PAFR signaling pathway to activate STAT1 via Jak2. This PAFR/Jak2/STAT1 signaling pathway resembles the IFN-beta, type I IFNR/Jak/STAT1 pathway described for LPS. Consequently, Gram-positive and Gram-negative bacteria appear to have different but analogous mechanisms for NO production.