A cysteine proteinase from sorghum malt variety SK5912 was purified by a combination of 4 M sucrose fractionation, ion-exchange chromatography on Q-and S-Sepharose (fast flow), gel filtration chromatography on Sephadex G-100 and hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The enzyme was purified 8.4-fold to give a 13.4% yield relative to the total activity in the crude extract and a final specific activity of 2057.1 U mg −1 protein. SDS-PAGE revealed two migrating protein bands corresponding to apparent relative molecular masses of 55 and 62 kDa, respectively. The enzyme was optimally active at pH 6.0 and 50 • C, not influenced across a relatively broad pH range of 5.0-8.0 and retained over 60% activity at 70 • C after 30-min incubation. It was highly significantly (P < 0.001) inhibited by Hg 2+ , appreciably (P < 0.01) inhibited by Ag + , Ba 2+ and Pb 2+ but highly significantly (P < 0.001) activated by Co 2+ , Mn 2+ and Sr 2+ . The proteinase was equally highly significantly (P < 0.001) inhibited by both iodoacetate and p-chloromercuribenzoate and hydrolysed casein to give the following kinetic constants: K m = 0.33 mg ml −1 ; V max = 0.08 µmol ml −1 min −1 .

The aerobic bacteria associated with soft rot in onions (Allium cepa) were isolated and identified as a Vibrio sp., Micrococcus epidermidis, Pseudomonas cepacia, an Acinetobacter sp., a Xanthomonas sp., Bacillus polymyxa, and Bacillus megaterium. With the cup-plate assay method, no pectin hydrolase could be detected from any of these isolates when they were cultured in pectin medium, but lyase and pectinesterases were detectable. Onion tissue cultures showed pectin hydrolase activity for P. cepacia and B. polymyxa and lyase and pectinesterase activities for all of the isolates, usually at higher levels of activity than those of the pectin medium culture filtrates. In both culture media, Vibrio sp. showed the highest lyase and pectinesterase activities. In the viscometric test, all of the isolates achieved at least a 50% decrease in viscosity for lyase enzyme, with M. epidermidis and Vibrio sp. recording viscosity decreases as high as 83%. The ability to cause soft rot in onion bulbs was demonstrated by P. cepacia and Xanthomonas sp. Benzoic acid at a concentration of 0.8 mg/ml caused total suppression of enzyme production, whereas sodium benzoate at this concentration reduced pectinesterase production by 71% and lyase production by 72%. The possible use of these preservatives in the control of soft rot in onions is noted.

Anaerobic and facultatively anaerobic bacteria associated with soft rot of yam (Diascorea rotundata) were isolated by the looping-out method and found to consist of Clostridium (three isolates), Corynebacterium (three isolates), Vibrio (one isolate), and Bacillus lentus (one isolate). Enzyme assay for hydrolase, lyase, and pectinesterase activities by the cup-plate method showed that except for Vibrio sp., B. lentus, and two isolates of Corynebacterium no pectinase activity could be detected for organisms cultured on pectin medium. Most of the cultures on yam tissue, however, showed activities for the three enzymes. The viscometric assay for hydrolase and lyase enzymes indicated a significant level of hydrolase activity (a 40.90% decrease in viscosity for Vibrio sp. and Corynebacterium spp.), but no lyase activity for most of the isolates. Two isolates of Corynebacterium and B. lentus caused changes in fresh yams suggestive of soft rot.

Summary The effect of pelleting on microbial population of standard diets and the sensitivity of some bacterial species to gamma radiation are presented. The pelleting treatment was shown to have a considerable effect on the numbers of all types of microorganisms present in the diet. With Erwinia and Xanthomonas as well as most fungi, a 100 % reduction in numbers was achieved. With the aerobic sporeformers the percentage reduction varied — Bac. brevis with 13 % showing the lowest. The irradiation experiment showed that Bac. polymyxa and Bac. alvei are highly sensitive to gamma radiation, being inactivated by a dose of 1 Mrad. The most resistant of the tested species were Bac. subtilis and Bac. licheniformis which required a dose of 3 Mrad for inactivation. Zusammenfassung Der Autor berichtet über die Auswirkung der Pelletierung von Standardfuttermitteln auf die mikrobielle Flora und die Empfindlichkeit einiger Bakterienarten gegenüber Gammabestrahlung. Es zeigte sich, daß die Pelletierung eine beachtliche Wirkung auf alle vorhandenen Mikroorganismen ausübte: Bei Erwinia und Xanthomonas sowie bei den meisten Pilzen wurde eine völlige (100 %) Reduktion erreicht. Bei aeroben Sporenbildnern war der Prozentsatz der Reduktion unterschiedlich — Bac. brevis zeigte mit 13 % die niedrigste. Die Bestrahlungsversuche zeigten, daß Bac. polymyxa und Bac. alvei, die bei einer Strahlungsdosis von 1 Mrad inaktiviert wurden, sehr strahlungsempfindlich sind. Die strahlungsresistentesten Arten waren Bac. subtilis und Bac. licheniformis; sie benötigten zur Inaktivierung eine Strahlungsdosis von 3 Mrad. Résumé L'auteur décrit l'action de la mise en granulés de fourrages standards sur la flore microbienne et la sensibilité de quelques espèces bactériennes au rayonnement gamma. La mise en granulés a exercé une action certaine sur tous les, microorganismes présents: Une réduction totale (100%) a été constatée pour Erwinia, Xanthomonas et la plupart des champignons. Le pourcentage de la réduction fut variable pour les sporulés aérobies. Bac. brevis a montré le pourcentage le plus faible avec 13 %. Les essais de rayonnements ont montré que Bac. polymyxa et Bac. alvei étaient très sensibles, étant inactivés avec une dose de rayons de 1 Mrad. Bac. subtilis et Bac. licheniformis furent des espèces résistantes au rayonnement; leur inactivation nécessita une dose de 3 mrad. Resumen El autor informa acerca del efecto de la granulación de piensos estandar sobre la flora microbiana y la sensibilidad de algunas especies bacterianas frente a la irradiación gamma. Se vió que el granulado ejerció un efecto considerable sobre todos los microorganismos presentes: en Erwinia y Xanthomonas, así como en la mayoría de los hongos, se consiguió una reducción total (100 %). En los esporógenos aerobios era diverso el porcentaje de reducción — Bac. brevis mostraba, con 13 %, la menor. Los ensayos de irradiación evidenciaron que Bac. polymixa, y Bac. alvei que se inactivaron con una dosis radiactiva de 1 Mrad, son muy sensibles a las irradiaciones. Las especies m...

Summary The levels of aflatoxin B1 in some commonly used components of laboratory animal diets were determined semi‐quantitatively. Aflatoxin B1 was detected in 6 of 16 of the diet components examined. The highest level was found in tapioca meal (0.075 mg./kg.) followed by fish meal (0.067 mg./kg.). No aflatoxin could be detected in any of the components normally used for the formulation of semi‐synthetic diets. Zusammenfassung Der Aflatoxin‐B1‐Gehalt von einigen gebräuchlichen Bestandteilen von Versuchstierfutter wurde semi‐quantitativ ermittelt. In 6 von 16 untersuchten Standardfutterbestandteilen wurde Aflatoxin B1 entdeckt. Den höchsten Gehalt zeigten Tapiokamehl (0,075 mg/kg) sowie Fischmehl (0,067 mg/kg). Futterkomponenten, die üblicherweise zur Herstellung halbsynthetischen Futters verwendet werden, wiesen keinen Aflatoxingehalt auf. Résumé On a recherché semi‐quantitativemeit le taux d'aflatoxine B1 de quelques composants usuels d'aliment d'animaux de laboratoire. Aflatoxine B1 fut trouvée dans sur 16 éléments examinés. La farine de tapioka (0,075 mg/kg) et la farine de Poisson (0,067 mg/kg) montrèrent les taux les plus élevés. Les composants alimentaires utilisés habituellement dans la fabrication d'un aliment semi‐synthétique ne contenaient pas d'aflatoxine. Resumen Se determinó semicuantitativamente el contenido en aflatoxina B1 de algunos componentes usuales de pienso para animales de experimentación. En 6 de 16 componentes de pienso estandar examinados se descubrió aflatoxina B1. El contenido máiximo lo presentaban la harina de tapioca (0,075 mg./kg.) y harina de pescado (0.067 mg./kg.). Los componentes de pienso, que se suelen utilizar corrientemente para la elaboración de piensos semisintéticos, no acusaban ningún contenido en aflatoxina.