Multiple xylanases of Cellulomona fimi are encoded by distinct genes

Cellulomonas fimi genomic DNA encoding xylanase activity has been cloned and expressed in Escherichia coli. As judged by DNA hybridization and restriction analysis, twelve xylanase-positive clones carried a minimum of four different xylanase (xyn) genes. The encoded enzymes were devoid of cellulase activity but three of the four bound to Avicel.     

Nitrile hydratase from a thermophilic Bacillus smithii

A novel thermophilic Bacillus smithii strain SC-J05-1, isolated from a hot spring, had the ability of hydrating nitrile to form amide. The nitrile hydratase was purified to homogeneity from the microbial cells of SC-J05-1 and was characterized. The enzyme was a 130-kDa protein composed of two different subunits (25.3 kDa and 26.8 kDa) and contained cobalt ions. This enzyme had the optimal temperature of 40°C and was stable up to 50°C. The optimal pH was in the alkaline region higher than pH 10. Received 02 September 1997/ Accepted in revised form 06 February 1998     

Implications of transgenic, insecticidal plants for insect and plant biodiversity

Genetically modified plants are widely grown predominantly in North America and to a lesser extent in Australia, Argentina and China but their regions of production are expected to spread soon beyond these limited areas also reaching Europe where great controversy over the application of gene technology in agriculture persists. Currently, several cultivars of eight major crop plants are commercially available including canola, corn, cotton, potato, soybean, sugar beet, tobacco and tomato, but many more plants with new and combined multiple traits are close to registration. While currently agronomic traits (herbicide resistance, insect resistance) dominate, traits conferring “quality” traits (altered oil compositions, protein and starch contents) will begin to dominate within the next years. However, economically the most promising future lies in the development and marketing of crop plants expressing pharmaceutical or “nutraceuticals” (functional foods), and plants that express a number of different genes. From this it is clear that future agricultural and, ultimately, also natural ecosystems will be challenged by the large-scale introduction of entirely novel genes and gene products in new combinations at high frequencies all of which will have unknown impacts on their associated complex of non-target organisms, i.e. all organisms that are not targeted by the insecticidal protein. In times of severe global decline of biodiversity, pro-active precaution is necessary and careful consideration of the likely expected effects of transgenic plants on biodiversity of plants and insects is mandatory.In this paper possible implications of non-target effects for insect and plant biodiversity are discussed and a case example of such non-target effects is presented. In a multiple year research project, tritrophic and bitrophic effects of transgenic corn, expressing the gene from Bacillus thuringiensis (Bt-corn) that codes for the high expression of an insecticidal toxin (Cry1Ab), on the natural enemy species, Chrysoperla carnea (the green lacewing), was investigated. In these laboratory trials, we found prey-mediated effects of transgenic Bt-corn causing significantly higher mortality of C. carnea larvae. In further laboratory trials, we confirmed that the route of exposure (fed directly or via a herbivorous prey) and the origin of the Bt (from transgenic plants or incorporated into artificial diet) strongly influenced the degree of mortality. In choice feeding trials where C. carnea could choose between Spodoptera littoralis fed transgenic Bt-corn and S. littoralis fed non-transgenic corn, larger instars showed a significant preference for S. littoralis fed non-transgenic corn while this was not the case when the choice was between Bt- and isogenic corn fed aphids. Field implications of these findings could be multifold but will be difficult to assess because they interfere in very intricate ways with complex ecosystem processes that we still know only very little about. The future challenge in pest management will be to explore how transgenic plants can be incorporated as safe and effective components of IPM systems and what gene technology can contribute to the needs of a modern sustainable agriculture that avoids or reduces adverse impacts on biodiversity? For mainly economically motivated resistance management purposes, constitutive high expression of Bt-toxins in transgenic plants is promoted seeking to kill almost 100% of all susceptible (and if possible heterozygote resistant) target pest insects. However, for pest management this is usually not necessary. Control at or below an established economic injury level is sufficient for most pests and cropping systems. It is proposed that partially or moderately resistant plants expressing quantitative rather than single gene traits and affecting the target pest sub-lethally may provide a more meaningful contribution of agricultural biotechnology to modern sustainable agriculture. Some examples of such plants produced through conventional breeding are presented. Non-target effects may be less severe allowing for better incorporation of these plants into IPM or biological control programs using multiple control strategies, thereby, also reducing selection pressure for pest resistance development.     

南海南沙海域沉积物中可培养微生物及其多样性分析

【目的】为了从南沙海域中分离获得微生物菌种资源，【方法】本文通过沉积物采样、可培养菌分离及16S rRNA鉴定，【结果】从22个站点的沉积物样品中获得349株细菌，分属于87个种。发现产芽孢细菌分布最广，并在10个站点的分离株中占多数；它们是Bacillus，Halobacillus，Brevibacillus，Paenibacillus，Pontibacillus和Thalassobacillus。其中芽孢杆菌（Bacillus）无论在数量上还是种类上都最多，分别属于34种，其中有8个可能的新种。此外，g-Proteobacteria是分离率较高的另一亚群；其中，假单胞菌（Pseudomonas），海杆菌（Marinobacter），食烷菌（Alcanivorax）属的细菌最多。统计还发现，在深度750~2000 m之间，低GC含量的细菌最丰富，而深度2000 m以下，分离株则全部为g-Proteobacteria。【结论】南沙沉积物可培养微生物中产芽孢细菌及 g-Proteobacteria比较丰富；其中，产芽孢细菌的多样性最高，具有进一步研究开发价值。     

Expression of a pepT homologue from Bacillus subtilis

Abstract We isolated pepT from Bacillus subtilis , a gene with homology to various tripeptidases from different bacterial sources, pepT is preceded by genes encoding a two component regulatory system. Its expression is activated during stationary phase. In minimal medium this activation is boosted in the presence of phosphate. The response regulator is preceded by putative promoter consensus sequences recognized by the stationary phase specific sigma factors σ ^H, σ ^F, and σ ^G. This is in accordance with the initiation of expression at the beginning of stationary phase. Inactivation of pepT causes no obvious phenotype.     

Frequency of the Insertion Sequence IS4Bsu1 among Bacillus subtilis Strains Isolated from Fermented Soybean Foods in Southeast Asia

Among 45 Bacillus subtilis strains isolated from non-salted types of fermented soybeans produced in several Southeast Asian countries, 20 had the insertion sequence IS4Bsu1 in the chromosome. In contrast, none of 49 B. subtilis strains of non-food origin contained IS4Bsu1. Frequent occurrence of this mobile DNA element in the soybean-fermenting B. subtilis would reflect the fact that few strains flourish on soybeans and thereby contribute to soybean fermentation.