Current Microbiology

Upadhyay, R.; Jayaswal, R.

doi: 10.1007/BF01579279pmid: N/A

Pseudomonas cepacia, a common soil and rhizosphere inhabitant, showed strong antagonism against several fungal plant pathogens. In dual cultures it greatly restricted the growth and conidial formation in several of these fungi. Growth restriction was associated with the frequent induction of a variety of morphological abnormalities such as chlamydoconidium formation, hyphal swellings, vacuolation and granulation of the mycelial contents, as well as lysis of hyphae and conidia. The induction of these deleterious morphological changes in fungi and inhibition of conidial formation were also found with a crude preparation of an antifungal compound fromP. cepacia. Mutants, defective in the production of this antifungal compound, failed to induce these morphological changes; this suggests that the antifungal compound is responsible for these abnormalities.

Chen, Jian; Zhang, Lanping; Song, Jiantao; Hwang, Fen; Dong, Qinghua; Liu, Jian; Qian, Yumin

doi: 10.1007/BF01579280pmid: N/A

The glycoproteins and glycolipids from membranes of virulent strain Z and avirulent strain M ofMycoplasma hyopneumoniae have been compared. The proteins and the glycoproteins were identified by SDS-polyacrylamide gel electrophoresis and concanavalin A-biotin labeling, respectively. The membrane preparation contained approximately 34 protein bands with molecular weights between 20 KD and 100 KD. The concanavalin A-biotin system reacted with a glycoprotein of a molecular weight of approximately 28,000 from avirulent strain M and did not react with the correspondent band from virulent strain Z. The membrane glycolipids of both strains consisted of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), and the percentages of 16∶0, 18∶0, and 18∶1 fatty acids comprised more than 80% of the total fatty acids of membrane glycolipids. The 18∶0 fatty acid of MGDG in avirulent strain M was twofold higher than that of virulent strain Z.

Ware, Cheryl; Bauchop, Tom; Hudman, J.; Gregg, Keith

doi: 10.1007/BF01579281pmid: N/A

A cryptic 2.85 kb plasmid (pBf1) was isolated from the rumen bacteriumButyrivibrio fibrisolvens strain AR10, ampped with restriction endonucleases, and cleavage sites suitable for attachment toEscherichia coli plasmids were identified. AR10 was not able to be cured of pBf1 by growth at 42°C or in 0.25 μg ampicillin/ml, but growth in 50 μg acridine orange/ml for three culture passages produced cured colonies at a frequency of <1%. Chimeric plasmids were constructed by combining pBf1 with theE. coli plasmid pUC18, in addition to the clindamycin resistance gene fromBacteroides fragilis plasmid pDP1 (pCW2 and pCW3), or the CAT gene fromE. coli plasmid pKK232-8 (pCK1). For plasmid construction, pBf1 was cleaved at two alternative restriction sites to increase the likelihood that replication control sequences would remain functional in at least one of the plasmids. Electroporation of AR10 yielded transformant populations that clearly maintained the plasmids and that appeared to express the ampicillinase gene of pUC18, although transformants were not readily selectable with any of the three antibiotics. The suitability of pBf1 as a replicon on which to base the construction of shuttle vectors was demonstrated clearly, by persistence of plasmid pCW3 in the absence of selective pressure, and the addition of appropriate selection factors is expected to yield practical transformation vectors.

Ahrné, Siv; Molin, Göran; Axelsson, Lars

doi: 10.1007/BF01579282pmid: N/A

A high-frequency transformation system was developed forLactobacillus reuteri with the electroporation technique. With this method, transformation frequencies of 107 transformants per μg DNA were routinely obtained with the plasmid pLUL631 and its derivatives. pLUL631, a nativeL. reuteri plasmid containing an erythromycin resistance determinant, was studied mainly with regard to replicon size and stability. The minimal replicon of the plasmid was shown to be located on a 2.4–3.1 kilobase pair fragment. pLUL631 was stably maintained in severalL. reuteri strains, but a deletion derivative, pLUL634, was unstable during growth under nonselective conditions. A hybrid plasmid, pLUL200, derived from the broad-host-range plasmid pVS1 and a part of the pLUL631 replicon, was shown to have higher copy number than both pLUL631 and pLUL634. The replicon of pLUL631 is suggested to be a suitable part of a food grade vector forL. reuteri.

Dadssi, Mustapha; Cozzone, Alain

doi: 10.1007/BF01579283pmid: N/A

Cellular extracts ofEscherichia coli severely impair the protein-phosphorylating activity in vitro of animal enzymes of both the casein-kinase type and the histone-kinase type. This blockade is due to a protein, probably dimeric, acting as a noncompetitive inhibitor, which has been purified to near-homogeneity from the soluble fraction of bacterial cells by chromatographic procedures.

Khawaja, Rubina; Neote, Kuldeep; Bingham, Hermine; Penner, John; Chan, Voon

doi: 10.1007/BF01579284pmid: N/A

Flagella are essential for motility and have been implicated to be one of the pathogenic determinants. The flagellum ofCampylobacter jejuni is a polymeric structure of a 62-kd protein. Using a high-affinity flagellin antibody to screen a lambda gt 11 phage genomic expression library ofC. jejuni strain TGH9011 (Serotype LIO36), a recombinant phage clone lambda gt 11RK that expresses theC. jejuni flagellin protein was isolated. The recombinant lambda gt 11 RK produced a 56-kd protein upon induction with isopropylthiogalactoside, which reacted specifically with anti-flagellin antibody. The flagellin gene was sequenced, and comparative analysis of the nucleotide and amino acid sequence identified a region of the flagellin that shows hypervariability among differentCampylobacter species and strains.

Bremer, Philip; Geese, Gill; Drake, Barney

doi: 10.1007/BF01579285pmid: N/A

A bacterium, designated CCI#8, that was isolated from a corroded copper coupon colonized both polished and unpolished copper surfaces under batch culture conditions. Atomic Force Microscopy (AFM) images revealed that the biofilm was heterogeneous in nature, both in depth and in cell distribution. Bacterial cells were shown to be associated with pits on the surface of the unpolished copper coupons. These observations support previous studies that CCI#8 is associated with the pitting corrosion of copper.

Gupta, R.; Batish, V.

doi: 10.1007/BF01579286pmid: N/A

Lactococcus lactis subsp.lactis 484 produced a proteinaceous antibacterial substance designated as ‘lactococcin’ capable of inhibiting members of theLactococcus group,Bacillus cereus, Staphylococcus aureus, andSalmonella typhi. Growth of this culture in the presence of 2–30 μg/ml of ethidium bromide or acriflavin or novobiocin, and at elevated temperature (39° and 41°C), could not produce any lactococcin-negative (Lap−) variants. However, protoplast-induced curing with lysozyme was successful in developing Lap− derivatives. Two types of cured derivatives, namely Lac− Lap+ and Lac− Lap−, were obtained. Lap− variants were also lacking sucrose-fermenting ability (Suc+) and lactococcin resistance (Lapr). The lactose-negative (Lac−) variants and Lap+ were clearly lacking the largest (65 Md) plasmid. However, Lap− Suc− Laps variants lost a 2 Md plasmid.L. lactis subsp.lactis 484 transferred lactose-fermenting ability as well as Lap+ Suc+ Lapr phenotypes simultaneously toL. lactis subsp.lactis LM 2306 and LM 0230 by surface mating at a frequency of 10−4 and 10−1 per donor respectively. However, cured Lac− Lap− transconjugants could not transfer Lac+ Lap+ Suc+ Lapr phenotypes to any of these recipient strains. Our results indicate that Lac+ and Lap+ Suc+ Lapr phenotypes are associated with 65 Md and 2 Md plasmids respectively. Conjugal transfer of 2 Md plasmid is possible only in the presence of a conjugative 65 Md plasmid.