Survival and virulence of salmonellae in water

Survival and virulence of salmonellae in drinking and surface waters were tested in a series of model experiments using suspensions of fresh strains of Salmonella enteritidis as a tester strain. Environmental conditions in surface water, modeled by the addition of increasing amounts of municipal sewage, were simulated to have the organic pollution load equivalent COD to 5.3-9.7-15.2 mg O2/l and the coliform counts ranging from 2 X 10 to 2 X 10(3) per ml water. The experiments were carried out at 4 degrees C and 20 degrees C, i.e. at temperatures simulating the two crucial points of the year-round thermal characteristics of water in the external environment. Suspensions of S. enteritidis in water had the initial density ranging between 1 X 10(2) and 1 X 10(4) (per ml, tests for virulence were carried out in the guinea pig eye (conjunctivitis reaction). Time of S. enteritidis survival in the drinking water free of organic pollutants was directly affected by the initial density of strain and indirectly by water temperature, in surface water the most significant variable turned out to be the degree of organic pollution: the time of survival clearly tended to shorten as the complex of organic pollutants in water increased. At the highest degree of organic pollution (COD concentration 15.2 mg per ml) S. enteritidis survival was restricted to less than 24 h whereas in drinking water it could reach up to 30 days. The survival time was always identical with the time of virulence persistence.     

Streptomyces rimosus extracellular proteases

Summary A trypsin-like proteinase was isolated from Streptomyces rimosus culture filtrates obtained from an oxytetracycline production process. The isolation procedure includes ultrafiltration, chromatography on CM-Sephadex, AH-Sepharose and CM-cellulose and gives a homogeneous protein with 19% yield. The enzyme is an anionic trypsin (M_r 28 000, pI 4.5), is stable from pH 4.5 to 9 and up to 40°C, and contains three disulphide bridges, three histidines and three methionines per molecule. At its pH optimum (pH 8.4–8.8) it splits peptide, ester and arylamide bonds of arginine in the endo-position and, to a smaller extent, in the exo-position. Like other streptomycete trypsins, it is a more efficient catalyst than bovine trypsin and has a relative preference for peptide-arylamides, N-benzyloxycarbonyl-l-norleucyl-l-prolyl-l-arginine-p-nitroanilide being by far its best substrate.     

Mycotoxins and Fusarium spp. associated with infected ears of corn in Minnesota.

Five Fusarium species were isolated from the grain of dent corn (Zea mays) selected from 20 of 32 damaged fields in 10 counties in Minnesota on the basis of hyphal growth visible on kernels in the field. Three mycotoxins were identified in the infected ears: zearalenone, deoxynivalenol, and 15-acetyl-deoxynivalenol. This is the first report of the presence of 15-acetyl-deoxynivalenol on corn ears in the field prior to harvest and in combination with deoxynivalenol and zearalenone. Ninety-nine cultures were selected from colonies growing from kernels on an agar medium; 30% of the cultures were F. graminearum, 23% were F. subglutinans, 20% were F. moniliforme, 14% were F. oxysporum, and 12% were F. proliferatum.     

Streptomyces rimosus extracellular proteases 3. Isolation and characterization of leucine aminopeptidase

Summary A leucine aminopeptidase was purified to homogeneity fromStreptomyces rimosus culture filtrates, which are waste broth of oxytetracycline bioproduction process. Purification procedure includes ultrafiltration and chromatography on CM-Sephadex, AH-Sepharose and FPLC Mono S column. The enzyme is a monomer with molecular weight of 27,500 Daltons and pI of 7.3, stable in broad pH range and up to 70°C. It is a metallo enzyme dependent on Ca²⁺ ions for its full activity. By its specificity it is a true aminopeptidase active on amino acid amide, arylamide, peptide and ester bonds. The hydrolysing activity shows preference for leucine at the N-terminal position of substrates, also acts on aromatic acids and methionine, but does not release glycine, proline, acidic amino acids orD-amino acid residues.     

ANTERIOR MEDIASTINAL TERATOMAS IN INFANTS AND CHILDREN

This report reviews the management of five pediatric patients with anterior mediastinal teratomas, and presents a discussion of symptoms, signs, and operative management of these lesions. Surgical resection was accomplished in all cases, with three of the five patients surviving. The two who died had malignant teratomas that were treated with adjunctive chemotherapy and X-ray therapy. Age at onset appears to be a significant factor in the prognosis of the disease.