Hydroperoxide inactivation of enzymes within spores of Bacillus megaterium ATCC19213

Abstract Hydroperoxide inactivation of the protoplast enzymes enolase, aldolase and glucose-6-phosphate dehydrogenase in intact spores of Bacillus megaterium ATCC19213 was assessed by first treating the cells with lethal levels of H₂O₂, then germinating them in the presence of chloramphenicol prior to permeabilization and enzyme assays. Glucose-6-phosphate dehydrogenase proved to be more sensitive to H₂O₂than enolase or aldolase, in agreement with findings for isolated enzymes. Average D values (time for 90% inactivation) for spores treated with 0.50% H₂O₂ were 173 min for enolase, 67 min for aldolase and 32 min for glucose-6-phosphate dehydrogenase, compared with a D value of 34 min for spore killing. H₂O₂ killing of spores was found to be conditional in that recoveries of survivors were greater on complex medium than on minimal medium. Overall, it appeared that oxidative inactivation of enzymes may be important for hydroperoxide killing of spores.     

壳聚糖固定化AS1．398中性蛋白酶稳定性的研究

对以壳聚糖为载体,由戊二醛作交联剂。制备的固定化ＡＳ１．３９８中性蛋白酶的稳定性进行了研究。实验结果表明,固定化ＡＳ１．３９８中性蛋白酶对热、乙醇、尿素以及ｐＨ值的稳定性均有明显的提高。     

Isolation of a gene essential for biosynthesis of the lipopeptide antibiotics plipastatin B1 and surfactin in Bacillus subtilis YB8

Bacillus subtilis YB8 was found to produce the lipopeptide antibiotics surfactin and plipastatin B1. A gene, lpa-8, required for the production of both lipopeptides was cloned from strain YB8. When this gene was inactivated in strain YB8, neither surfactin nor plipastatin B1 was produced. However, the defective strain transformed with an intact lpa-8 gene had restored ability to produce both peptides. Nucleotide sequence analysis of the region essential for the production of the peptides revealed the presence of a large open reading frame. The deduced amino acid sequence of lpa-8 (224 amino acid residues) showed sequence similarity to that of sfp (from surfactin-producing B. subtilis), lpa-14 (from iturin A- and surfactin-producing B. subtilis), psf-1 (from surfactin-producing Bacillus pumilus), gsp (from gramicidin-S-producing Bacillus brevis), and entD (from siderophore-enterobactin-producing Escherichia coli), which are able to complement a defect in the sfp gene and promote production of the lipopeptide antibiotic surfactin. The sequence similarity among these proteins and the product similarity of cyclic peptides suggests that they might be involved in the biosynthesis or secretion of the peptides. Received: 14 July 1995 / Accepted: 22 December 1995     

复合诱变原生质体选育耐热碱性蛋白酶高产菌

以地衣芽孢杆菌(Bacillus licheniformis)53号为原始菌株,在原生质体形成和再生的最佳条件下制备原生质体,对原生质体进行复合诱变,对大量再生突变株进行筛选,最终获得了高产、稳定、耐热的碱性蛋白酶产生菌53-G38-6,产酶活力由1104U/ml提高到22080U/ml。适宜的发酵条件:培养基(％)胰蛋白胨1,酵母膏0.5,玉米粉5,Na_2HP0_4·12H_20 0.4,KH_2P0_4 0.03,Na_2CO_3 0.1,自然pH。42℃旋转培养44～48h,得到的蛋白酶热稳定性强,60℃处理1h剩余酶活55％。酶反应最适条件:62℃,pH10.0,在pH9～10.5范围内稳定。     

Development of insect resistance in tomato plants expressing the δ-endotoxin gene ofBacillus thuringiensis subsp.tenebrionis

A crystal -endotoxin gene ofBacillus thuringiensis subsp.tenebrionis (B.t.t.) encoding a coleopteran insect-specific toxin was used to construct a chimeric gene which expressed the toxin in plant cells. Via anAgrobacterium tumefaciens binary vector system, the toxin gene was transferred into tomato cells. From leaf disks recombinant plants were regenerated. Hybridization experiments demonstrated that these plants synthesized toxin-specific mRNA of the expected size. Transgenic tomato plants with the chimericB.t.t. toxin gene contained a 74 kDa protein which cross-reacted with toxin antibodies. The expression caused a significant insecticidal activity of the transgenic tomato plants against Colorado potato beetle larvae.     

Transient reduction in secreted 32 kD chitinase prevents somatic embryogenesis in the carrot (Daucus carota L.) variant ts11

At the nonpermissive temperature, somatic embryos of the temperature-sensitive (ts) carrot (Daucus carota L.) cell variant ts11 only proceed beyond the globular embryo stage in the presence of medium conditioned by wild-type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium from ts11 embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect on ts11 embryo development could be detected between the 32 kD chitinase purified from wild-type cultures and the chitinase from ts11 cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in a ts11 embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature-sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype of ts11 is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that the ts11 phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley-Liss, Inc.     

原噬菌体PBSX阻遏基因及其温度敏感型等位基因的克隆分析

本研究利用聚合酶链式反应技术,成功地克隆了枯草芽孢杆菌缺陷型原噬菌体ＰＢＳＸ阻遏基因及其温度敏感型等位基因。核苷酸序列分析发现,野生型及其温度敏感型阻遏基因之间的碱基变异较大,但却存在几乎完全相同的开放读框,尤其是开放读框ｏｒｆⅠ,可能编码着１１３个氨基酸的阻遏蛋白,并且还推定了开放读框的启动区和核糖体结合位点。通过互补实验,证实了野生型阻遏基因的产物能够抑制温度诱导ＰＢＳＸ原噬菌体,表明克隆的基因有着正常的生物活性。     

我国仓贮昆虫病原芽孢杆菌的研究

对９５１个样品分离鉴定,有７４７个样品含芽孢杆菌,有菌率为７８．５５％．共分离得到芽孢杆菌１１３８株,其中苏云金杆菌（Ｂａｃｉｌｌｕｓｔｈｕｒｉｎｇｉｅｎｓｉｓ,简称Ｂ．ｔ）１４３株,占１２．５％;球形芽孢杆菌（Ｂａｃｉｌｌｕｓｓｐｈａｅｒｉｃｕｓ,简称Ｂ．ｓ）１１株,占０．９７％;其他芽孢杆菌９８４株,占８６．４０％．从芽孢杆菌中选出产生晶体、苏云金素或磷酸酯酶Ｃ（ＰｈｏｓｐｈａｌｉｐａｓｅＣ,简称ＰＬＣ）的毒素菌株１６８株,其中Ｂ．ｔ占１４３株,Ｂ．ｓ有５株,其他芽孢杆菌１０株．在产毒素菌株中,经测定有１２０株菌对供试昆虫毒性达标．占７７．９２％．不同菌株的杀虫毒素、杀虫范围和毒力各异,认为这种差异取决于毒素和虫种两方面的特异性．