地衣芽孢杆菌原生质体的制备、再生及转化研究

目的：提高地衣芽孢杆菌原生质体的产量和形成率,为进一步提高原生质体转化率打下基础。方法：通过酶解法对地衣芽孢杆菌工业生产菌株Bacillus licheniformis303原生质体的制备及再生条件进行了研究。考察了菌体生长状态、溶菌酶浓度、处理时间、渗透压稳定剂和再生培养基等因素对地衣芽孢杆菌原生质体的制备及再生的影响。结果：对数生长后期的菌体,以SMMP作渗透压稳定剂,溶菌酶浓度为100mg/mL,37℃下酶解30min,原生质体生成量可达8×109个/mL;再生培养基选用含1mol/L琥珀酸钠的DM3时,再生率最高可达17%。在此条件下,采用PEG法将游离型质粒pHY-P43-secQ转化宿主菌B.lichenifor-mis303,转化率可达10~15 CFU/μg DNA。     

Relationship Between Competence for Transformation of Bacillus subtilis with Native and Single-Stranded Deoxyribonucleic Acid

The response of populations of Bacillus subtilis to both native deoxyribonucleic acid (DNA) and denatured DNA was investigated at maximal competence and at various times during the development of compentency. The results indicate that competence for transformation with native and denatured DNA increases and decreases simultaneously. Competition occurs between native and single-stranded DNA during transformation, and the same cells in a population can be doubly transformed by DNA molecules of both configurations.     

Spontaneous Transformation and Its Use for Genetic Mapping in Bacillus subtilis

Using a simple semi-synthetic competence and sporulation medium (CSM), we found evidence that Bacillus subtilis cells transformed in the competence phase can sporulate, indicating that genetic information acquired during the competence phase is inherited by the next generation after germination of the transformed spores. Moreover, the results from mixed cell culture experiments suggest that spontaneous genetic transformation can occur between competent cells and DNA released from lysed cells in the natural environment. We also found evidence that the spontaneous transformation system can be used for genetic mapping in B. subtilis.     

Development of Competence in the Bacillus subtilis Transformation System

Competence in Bacillus subtilis, assayed by the ability of cells to be transformed with bacterial deoxyribonucleic acid (DNA) or transfected by phage DNA, has been shown to occur in a single semisynthetic medium with peak activity occurring 3 hr after the cessation of logarithmic growth. No step-down conditions or culture manipulations were necessary for routine transfection of 1% of the population. The results demonstrate that bacteriophage DNA is a valid assay for studying the development of competence in B. subtilis. Predictions of workers using transforming bacterial DNA, who have suggested that competence in B. subtilis is associated with a specific phase of growth, are substantiated. The peak of competence is not affected by marked differences in the rate of growth during the logarithmic phase. The effect on development of competence by this procedure of some components (including casein hydrolysate, tryptophan, and histidine) which were routinely included in the transformation medium by other investigators has been determined by use of infectious phage DNA as an assay. We have demonstrated that tryptophan, as well as histidine, increases the transformation frequency—even in strains which do not have auxotrophic demands for these components. Glutamic acid and alanine depress optimal levels of transfection.     

Anaerobic Production of a Biosurfactant by Bacillus licheniformis JF-2

Bacillus licheniformis JF-2 anaerobically produced a biosurfactant when grown in a glucose-mineral salts medium containing yeast extract and NaNO₃. Surface tension of the medium was reduced from 70 to 74 mN/m to as low as 28 mN/m due to the production of an anionic biosurfactant.     

嗜热脂肪芽孢杆菌质粒DNA的高压电穿孔转化研究

采用高压电穿孔法将穿梭质粒导入了嗜热脂肪芽胞杆菌(Bacillusstearothermophilus)K1041和T521菌株.以对数生长后期的菌体制备K1041转化细胞,以LB平板上于50℃培养的过夜菌制备T521转化细胞,细胞密度为5～7×109细胞/mL.电击条件如下电容25μF,电场强度10.0KV/cm,脉冲控制器设定200Ω.K1041和T521最高转化效率分别达2.01×104和1.19×102转化子/μgDNA.此外,研究发现T521和K1041中存在着DNA的限制/修饰系统.     

Production of alkaline protease with Bacillus licheniformis in a controlled fed-batch process

Summary A production method for alkaline serine protease with Bacillus licheniformis in a synthetic medium was developed. Employing closed-loop control of oxygen, nitrogen and carbon source the pO₂ was held at 5%, the ammonium concentration kept below 1 mM and the glycerol concentration was maintained between 20 and 100 mM. Protease production was monitored by flow injection analysis. Thus, in a fed-batch procedure production could be increased 4.6-fold in comparison to an uncontrolled batch process.Offprint requests to: G. Bierbaum     

Production of the Novel Two-Peptide Lantibiotic Lichenicidin by Bacillus licheniformis DSM 13

Background

Lantibiotics are small microbial peptide antibiotics that are characterized by the presence of the thioether amino acids lanthionine and methyllanthionine. Lantibiotics possess structural genes which encode inactive prepeptides. During maturation, the prepeptide undergoes posttranslational modifications including the introduction of rare amino acids as lanthionine and methyllanthione as well as the proteolytic removal of the leader. The structural gene (lanA) as well as the other genes which are involved in lantibiotic modification (lanM, lanB, lanC, lanP), regulation (lanR, lanK), export (lanT(P)) and immunity (lanEFG) are organized in biosynthetic gene clusters.

Methodology/Principal Findings

Sequence comparisons in the NCBI database showed that Bacillus licheniformis DSM 13 harbours a putative lantibiotic gene cluster which comprises two structural genes (licA1, licA2) and two modification enzymes (licM1, licM2) in addition to 10 ORFs that show sequence similarities to proteins involved in lantibiotic production. A heat labile antimicrobial activity was detected in the culture supernatant and a heat stabile activity was present in the isopropanol cell wash extract of this strain. In agar well diffusion assays both fractions exhibited slightly different activity spectra against Gram-positive bacteria. In order to demonstrate the connection between the lantibiotic gene cluster and one of the antibacterial activities, two Bacillus licheniformis DSM 13 mutant strains harbouring insertions in the structural genes of the modification enzymes licM1 and licM2 were constructed. These strains were characterized by a loss of activity in the isopropanol extract and substractive MALDI-TOF predicted masses of 3020.6 Da and 3250.6 Da for the active peptides.

Conclusions/Significance

In conclusion, B. licheniformis DSM 13 produces an antimicrobial substance that represents the two-peptide lantibiotic lichenicidin and that shows activity against a wide range of Gram-positive bacteria including methicillin resistant Staphylococcus aureus strains.     

Production of protease with Bacillus licheniformis mutants insensitive to repression of exoenzyme biosynthesis

Two mutant strains of Bacillus licheniformis insensitive to catabolite repression were selected by classical mutagenesis in connection with the development of a fed-batch procedure for protease production. B. licheniformis 4a produced up to 20 U (Anson-Units) subtilisin Carlsberg/ml in fed-batch experiments in the presence of up to 1.5 m glycerol, but was inhibited by excess ammonium. Formation of spores, excretion of -amylase and the biosynthesis of citrate synthase and isocitrate dehydrogenase were likewise not repressed by glycerol. The strain was characterized by unusually low activity of the -oxoglutarate dehydrogenase complex and increased biosynthesis of polyglutamic acid in the presence and excretion of -oxoglutarate in the absence of ammonium, respectively. The results are discussed in view of a possible connection between the defect in the -oxoglutarate dehydrogenase complex and insensitivity to catabolite repression. The second strain B. licheniformis 114 was able to synthesize 11.5 U protease/ml independently of the glycerol and ammonium concentration in the medium. Correspondence to: G. Bierbaum     

Optimization of Cultivation Medium for the Production of Bacillus intermedius 3-19 Glutamyl Endopeptidase

The effect of some components of cultivation medium on the growth of the streptomycin-resistant Bacillus intermedius strain 3-19 and on the production of glutamyl endopeptidase was investigated using factorial experimental design, which allowed the concentrations of peptone and inorganic phosphate to be optimized for the maximum production of the enzyme. Experiments with different peptones and casamino acids showed that the enzyme production is maximum with peptone 3 of plant origin. The addition of casamino acids or amino acids to the peptone-containing cultivation medium inhibited the production of glutamyl endopeptidase.     

Production and partial characterization of bacteriocin-like pepitdes by Bacillus licheniformis ZJU12

Bacillus licheniformis ZJU12, which was isolated from soil, could produce bacteriocin-like peptides that exhibited a broad spectrum of antagonistic activity against various species of Gram-positive bacteria and fungal pathogens, but not against Gram-negative bacteria tested except Xanthomonas oryzae pv. oryzae, a rice pathogen. The bacteriocin-like peptides were sensitive to proteinase K and trypsin. The activity was stable during temperature exposure up to 100 °C for 30 min, but lost completely at 121 °C for 15 min. The cell-free supernatant of B. licheniformis ZJU12 was shown to retain the activity within the pH range of 2–9, and the optimum pH for the activity was about 6.5. No adverse effect of the antagonistic compound to mice was observed in acute toxicity tests with the dose of 0.8 mg/20 g.     

Multiple Regulatory Events in the Development of Competence for Genetic Transformation in Haemophilus influenzae

Cyclic adenosine 3',5'-monophosphate derepresses enzyme synthesis but does not yield high levels of transformability or detectable levels of competence-related envelope polypeptides. Additional regulatory events must trigger complete expression of competence.     

Production in sea-water of thermostable alkaline proteases by a halotolerant strain of Bacillus licheniformis

A halotolerant strain of Bacillus licheniformis, previously isolated from marine sediments, produced high protease activity during the early stationary phase of growth. The use of sea-water in the fermentation medium enhanced the production of this activity of 150%. After a partial purification, three different proteolytic enzymes could be detected, which were alkaline serine proteases, exhibiting optimal activity at pH 9.0 and at 70°C. The proteases were activated by NaCl, with a two, three-fold increase in activity and were stable in presence of 0.7% NaBO3, 0.5% NaClO and 3% H2 O2. © Rapid Science Ltd. 1998     

Development of an asporogenic Bacillus licheniformis for the production of keratinase

AIMS: Bacillus licheniformis PWD-1 is a keratin-degrading, spore-forming bacterium isolated from a poultry waste digester. A sporulation-deficient mutant of B. licheniformis PWD-1, named B. licheniformis WBG, was developed and characterized. METHODS AND RESULTS: The mutation was generated using the splicing by overlap extension PCR method (Gene SOEing) to create 256 bp deletion in the spoIIAC gene, which encodes an essential sporulation-specific sigma factor. In vivo gene replacement was accomplished with the use of a temperature-sensitive plasmid that is able to integrate and excise the nucleotide fragment 256 bp from the B. licheniformis chromosome. PCR analysis and DNA sequencing confirmed the spoIIAC gene deletion. Heat-treatment assays and electron microscopy verified the absence of spores. CONCLUSIONS: This asporogenic strain is able to express normal levels of keratinase when compared with its wild-type host. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, a method of constructing a stable sporulation-defective strain was developed. It can be potentially useful as a tool to generate asporogenic strains of Bacillus that retain their industrial capabilities for production of exoproteases and other exozymes.     

Hyper-Resistance of the Bacillus licheniformis 24 Strain to Oxidative Stress Is Associated with Overexpression of Enzymatic Antioxidant System Genes

Molecular Biology - At the International Space Station (ISS), artificial living conditions are created and maintained to satisfy human needs, these conditions are also favorable for the growth of...