Both Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis produce mosquitocidal toxins during sporulation and are extensively used in the field for control of mosquito populations. All ...the known toxins of the latter organism are known to be encoded on a large plasmid, pBtoxis. In an attempt to combine the best properties of the two bacteria, an erythromycin resistance-marked pBtoxis plasmid was transferred to B. sphaericus by a mating technique. The resulting transconjugant bacteria were significantly more toxic to Aedes aegypti mosquitoes and were able to overcome resistance to B. sphaericus in a resistant colony of Culex quinquefasciatus, apparently due to the production of Cry11A but not Cry4A or Cry4B. The stability of the plasmid in the B. sphaericus host was moderate during vegetative growth, but segregational instability was observed, which led to substantial rates of plasmid loss during sporulation.
Five typing methods were evaluated, utilising 63 strains of fluorescent pseudomonads, to assess their usefulness as tools to study the bacterial diversity within this complex group. The methods used ...were Biolog metabolic profiling, restriction fragment length polymorphism ribotyping, PCR ribotyping, and repetitive element sequence-based PCR (rep-PCR) utilising BOX and enterobacterial repetitive intergenic consensus (ERIC) primers. Cluster analysis of the results clearly demonstrated the considerable homogeneity of
Pseudomonas aeruginosa isolates and, conversely, the heterogeneity within the other species, in particular
P. putida and
P. fluorescens, which need further taxonomic investigation. Biolog metabolic profiling enabled the best differentiation among the species. Rep-PCR proved to be highly discriminatory, more so than the other DNA fingerprinting techniques, demonstrating its suitability for the analysis of highly clonal isolates. RFLP ribotyping, PCR ribotyping, and rep-PCR produced specific clusters of
P. aeruginosa isolates, which corresponded to their origins of isolation, hence we recommend these methods for intraspecific typing of bacteria.
We previously reported the presence of both haloalcohol and haloalkanoate dehalogenase activity in the Agrobacterium sp. strain NHG3. The versatile nature of the organism led us to further ...characterise the genetic basis of these dehalogenation activities. Cloning and sequencing of the haloalcohol dehalogenase and subsequent analysis suggested that it was part of a highly conserved catabolic gene cluster. Characterisation of the haloalkanoate dehalogenase enzyme revealed the presence of two stereospecific enzymes with a narrow substrate range which acted on D-2-chloropropionic and L-2-chloropropionoic acid, respectively. Cloning and sequencing indicated that the two genes were separated by 87 bp of non-coding DNA and were preceded by a putative transporter gene 66 bp upstream of the D-specific enzyme.
American foulbrood in honey bees Chantawannakul, Panuwan; Dancer, Brian N
Bee world,
01/2001, Letnik:
82, Številka:
4
Journal Article
Recenzirano
In recent years, one of the major problems hampering the development of apiculture is the disease American foulbrood (AFB). In this article, AFB is reviewed in detail, including its detection and ...diagnosis, prevention and control. Paenibacillus larvae larvae, the causative agent of the disease, is also examined. Products of P. I. larvae culture are mentioned, particularly the antibiotic substances and proteases.
The Proteases of American Foulbrood Scales Dancer, Brian N.; Chantawannakul, Panuwan
Journal of invertebrate pathology,
09/1997, Letnik:
70, Številka:
2
Journal Article
Recenzirano
The gross protease activity of pathological samples of American foulbrood-infected cadavers from several UK sources was studied. In all cases the bulk of the activity is caused by neutral protease(s) ...(optimum pH ca. 6.8) that are inhibited by chelating agents such as EDTA and 1,10 phenanthroline (indicating metalloproteases) but not by inhibitors of other classes of proteolytic enzymes. The proteases, which derive from the infectious agent of AFB,Paenibacillus larvae,were unusual in being insensitive to phosphoramidon and in not degrading FAGLA, the artificial substrate specific for mostBacillusmetalloproteases. The enzymes in AFB ropes and scales had temperature optima of 60–65°C and were inactivated quickly on incubation at 80°C. Activity at moderate temperatures (37°C) was great on general substrates such as casein, gelatin, and hide powder azure, slight on elastin-Congo red, and nonexistent on collagen. In SDS–polyacrylamide gels the enzymes from the various sources all had molecular weights about 24 kDa. The proteases could be detected only zymographically after brief washing to remove SDS. On silver-stained gels no bands corresponding to the enzymes' activities could be detected. On native polyacrylamide gels enzyme activity was resolved zymographically as at least three metalloprotease bands with samples from different sources showing a variety of patterns.
Methods have been developed for chemical transformation and electro-transformation (electroporation) of vegetative cells of Bacillus anthracis with supercoiled plasmid DNA. Chemical transformation ...was dependent on incubation in Tris/HCl with osmotic support and transformation with plasmid DNA was effected by treatment with polyethylene glycol 3350. Maximum transformation frequencies were 3.8 x 10(-5) transformant c.f.u. per viable c.f.u. (1 x 10(3) c.f.u. per micrograms DNA). Optimal frequencies were pH dependent and were affected by growth-medium composition. Transformation was not observed with linear or multimeric plasmid DNA. Electro-transformation of B. anthracis using high field intensity electroporation was dependent on the composition of both the growth medium and the electroporation buffer. Maximum electro-transformation frequencies were 5.3 x 10(-4) c.f.u. per viable c.f.u. (2.6 x 10(4) c.f.u. per micrograms DNA). The use of early exponential phase cells was critical to both procedures and the maximum efficiency (c.f.u. per micrograms DNA) of each system was strain dependent under the conditions described.
Phosphatidylserine has been found in extracts of Bacillus licheniformis made under alkaline conditions but not under neutral or acidic ones and was derived from the tRNA fraction. In tRNA ...preparations kept below neutrality during purification, phosphatidylserine was the only phospholipid released when the pH was raised to 9.0. The amount of bound phosphatidylserine could be increased by incubating tRNA from B. licheniformis or Escherichia coli with CTP and phosphatidic acid in the presence of an S-30 extract from either organism. The tRNA carrying phosphatidylserine has been separated from the bulk of the tRNA by DEAE-Sephadex chromatography in the presence of a detergent. On deaminoacylation of this material and rechromatography on DEAE-Sephadex, a number of peaks were found, indicating that this behavior is not confined to a single isoaccepting species.
PDF
