Microbiological Studies of Coli-aerogenes Bacteria

α-Ketoglutarate was obtained in a very small amount by the oxidative fermentation of acetate with either a growing culture or the washed cells of Escherichia coli. This microorganism was also observed to accumulate a considerable amount of α-ketoglutarate as the oxidation-product of C₄-dicarboxylic acids such as succinate, fumarate, malate and oxalacetate. The addition of acetate to the reaction mixtures containing either C₃- or C₄-acids brought about an increase in the yield of α-ketoglutarate. The bacteria of coli-aerogenes revealed an ability of oxidizing tricarboxylic acids under suitable conditions, but there was no noticeable production of α-ketoglutarate. The formation of glyoxylate was observed to occur during the degradation of citrate by the bacteria of coli-aerogenes. Finally, a cyclic mechanism of aerobic carbon-metabolism in the bacteria was propounded and discussed.     

Microbiological Studies of Coli-aerogenes Bacteria

During investigations on the metabolisms of glucose by coli-aerogenes bacteria, it was found that the bacteria accumulated a large amount of α-ketoglutaric acid under aerobic conditions such as shaking culture, while lactic acid was ascertained to be produced anaerobically by the bacteria as was already known.     

Microbiological Studies of Coli-aerogenes Bacteria

The presence of glucose-6-phosphate markedly stimulated the anaerobic utilization of glyoxylate by either cell-free extracts or partially purified enzyme preparations of coli-aerogenes bacteria. The enzymic reduction of glyoxylate to glycollate was found to occur in the presence of TPN with the following substrates; glucose-6-phosphate, glucose plus ATP, gluconate plus ATP, glucose-1-phosphate or malate. The data indicated that the reduction of glyoxylate to glycollate was coupled to the oxidation of glucose-6-phosphate via the hexose monophosphate shunt pathway. It was propounded that the operation of the hexose monophosphate oxidative pathway might be controlled by TPN-linked glyoxylic reductase, and the mechanisms of enzymic regulation in microbial respiration were also discussed.     

Coli-aerogenes Bacteria on Plants

S ummary . Specimens of plant foliage and flowers collected in the region of Attica from various situations and geographical regions were examined over a period of 13 months for the presence of coli-aerogenes bacteria able to grow at 37°. Twenty-five (12.2%) of 204 specimens carried coli-aerogenes bacteria of which Escherichia coli type I was isolated from 12 (5.8%). Coli-aerogenes bacteria were seldom isolated from plants grown in uninhabited areas, and they occured more frequently during summer and autumn.
Vegetables and fruits sold in the central market of Athens are frequently contaminated with coli-aerogenes bacteria. Of 76 specimens of vegetables examined 66 (86.8%) were positive for coli-aerogenes bacteria, and 17 (22.3%) for E. coli type I. The figures from 41 specimens of fruits were 26 (65.8%) and 4 (9.7%), respectively.     

Microbiological Studies of Phytopathogenic Bacteria

During investigations on the catabolism of carbohydrate by the bacteria of the genus Erwinia, it was found that a large amount of 2-ketogluconic acid was aerobically produced from glucose by several strains of the Erwinia amylovora group of bacteria, while no production of 5-ketogluconic acid was ascertained in their growing cultures.     

Studies on Coli-aerogenes and Other Gram-negative Intestinal Bacteria in Various Animals and Birds

S ummary . Some faecal material from native animals and birds (especially) showed either no coli-aerogenes bacteria or contained types other than Escherichia coli I.
Amongst coli-aerogenes isolates, E. coli I was frequent but the high percentage of other biotypes indicated that the animal host may serve as a pool of intermediate and irregular strains. Paracolons and Proteus spp. were abundant, and Salmonella spp. were isolated from dogs and native animals possibly in contact with man.
Animals were only occasionally carriers of enteropathogenic E. coli serotypes and seldom of types locally important in the etiology of infantile diarrhoea, such as E. coli O26:B6 and O55:B5. In this series O86 serotypes other than the diarrhoeal strain isolated from babies were found. The results of the study indicated some degree of host specificity. In the group of 20 O serotypes (referred to as specific E. coli ), O8 was most commonly listed. Most strains were sensitive to chemotherapeutic agents but resistance of some strains especially to sulphonamide was recorded.
The implication of the presence in the animal gut of coli-aerogenes bacteria other than E. coli type I is discussed in relation to bacterial standards for drinking water.     

The Effects of Feeding Tetracycline, Nitrovin and Quindoxin on the Drug-Resistance of Coli-aerogenes Bacteria from Calves and Pigs

A study of calves and pigs was made to compare the effects on intestinal coli-aerogenes bacteria of feeding diets medicated with tetracycline, nitrovin or quindoxin. Results showed that even before the introduction of medicated diets, drug-resistant coli-aerogenes bacteria were present in surprisingly high numbers. However, it was clear with both animal species that only tetracycline had a selective effect. With calves a resistance to furazolidone was frequently present in tetracycline-resistant organisms. Analysis of the resistance patterns supported the contention that the dominant coli-aerogenes bacteria in the gut flora following use of certain growth-promoters, resulted from suppression of fully sensitive organisms: the distribution of the various resistance patterns was independent of the agent used and whether or not the diet was medicated. There was no significant difference in the trans-missibility of resistance genes between calves and pigs receiving either tetracycline or quindoxin or neither treatment. Results obtained with nitrovin were thought to be similar but, inexplicably, the control animals all gave low values.     

Studies on the Microbiological Transformation of Steroids

An attempt was made to clarify how Pellicularia filamentosa f. sp. microsclerotia IFO 6298 capable of hydroxylating C₂₁-steroids at the C-19 position converts C₁₉-steroids, especially monohydroxyderivatives of androst-4-ene-3, 17-dione. Such substrates as 11β-hydroxyandrost-4-ene-3,17-dione (I), androst-4-ene-3, 11, 17-trione (II), androsta-1,4-diene-3, 17-dione (III), 11β-hydroxyandrosta-1,4-diene-3,17-dione (IV), 14α-hydroxyandrost-4-ene-3, 17-dione (V), 15α-hydroxyandrost-4-ene-3, 17-dione (VI) and 9α-hydroxyandrost-4-ene-3, 17-dione (VII) were converted by the organism. All the main and several minor products were then isolated and identified. As a result it is concluded that this organism converts I and II into 14α-hydroxyandrost-4-ene-3,11,17-trione, III and IV into 14α-hydroxyandrosta-1,4-diene-3,1l,17-trione, V into 11α 14α dihydroxyandrost-4-ene-3, 17-dione (main) and 11β, 14α-dihydroxyandrost-4-ene-3, 17-dione (minor, a tentative structure), VI into 11β, 15α-dihydroxyandrost-4-ene-3,17-dione (main) and 15α-hydroxyandrost-4-ene-3,11,17-trione (minor, a tentative structure) and VII into 9α, 14α-dihydroxyandrost-4-ene-3, 17-dione (main) and 6β, 9α-dihydroxyandrost-4-ene-3,17-dione (minor).

In addition, the structural requirement of substrate for the 19-hydroxylation catalyzed by the organism and the influence of a hydroxyl group on steroid nucleus upon the 11β- and 14α-hydroxylations and the 11β-OH-dehydrogenation was discussed.     

Studies on the Microbiological Transformation of Steroids

The microbiological reduction of the 20-carbonyl group of steroids has been investigated. Candida pulcherrima IFO 0964 and Sporotrichum gougeroti IFO 5982 converted the following substrates into the corresponding 20β-hydroxy derivatives (yields of the products are indicated in parentheses): Reichstein’s Compound S (60~70%) and 17α,21-dihydroxypregna-l,4-diene- 3,20-dione (40~80%). Rhodotorula glutinis IFO 0395 converted the following substrates into the corresponding 20α-hydroxy derivatives: Reichstein’s Compound S (65%), 17 α,21-dihydroxy- pregna-l,4-diene-3,20-dione (80%), llβ,l7α-dihydroxypregn-4-ene-3,20-dione (45%) and 17α, 19,21 -trihydroxypregn-4-ene-3,20-dione (10%).     

Studies on the Microbiological Transformation of Steroids

Some features of the NMR spectra of 19-hydroxy- and 19-acetoxy-steroids were presented and by making use of the features an unknown product of a microbiological transformation of 17α,20α,21-trihydroxypregn-4-en-3-one was easily characterized as a 19-acetoxysteroid.     

高效脱硫诱变菌株降硫性能的研究

目的:筛选具有脱硫功能的细菌,为采用生物法脱硫奠定理论基础.方法:从大庆石化废水曝气池中采集5个活性污泥样本,经过富集培养、分离、纯化获得具有典型特征的菌株,采用碘量法对这些菌株进行降硫能力测定,从中选择降硫效率较高的菌株进行诱变.结果:在30℃、转速160r/min的条件下,Z39ay1菌株的最佳生长pH值为7.0,对数生长期为12～32h,当硫离子为102.24mg/L时,该菌株对硫化物的降解率达42.60％,将其置于2000Gry的60Co射线下照射,从存活菌细胞中进行筛选获得1株诱变菌株Z39a,当硫离子浓度为60mg/L时,对硫化物的降解率达98.58％.结论:从大庆石化废水中分离纯化出1株代号为Z39ay1菌株,经鉴定为赖氨酸芽孢杆菌,诱变后获得菌株Z39a,其降硫效果比出发菌株有大幅度的提高.     

Preliminary Microbiological Studies on the Preservation of Palm Wine

Palm wine is essentially a heavy suspension of yeasts and bacteria in fermenting palm sap. The water extract of a local preservative, from the bark of Sacoglottis gabonensis , failed to inhibit several yeasts and bacteria from palm wine. Sodium metabisulphite, diethylpyrocarbonate (DEPC) and sorbic acid inhibited to varying extents micro-organisms in palm wine. Sorbic acid was thought to be the most suitable preservative tested since DEPC left a residual pungent smell and sodium metabisulphite was not suitable because it is unacceptable to man above 0.35 mg/kg of body weight (Mossel, 1971). Pasteurization at 70° for 30 min was more effective than any of the chemical methods in reducing the microbial load of the wine. It is suggested that pasteurization at 70° for 30 min combined with subsequent treatment with sorbic acid may prove useful as a means of preserving palm wine.     

Studies on Glucose Isomerase of Bacteria

A bacterial strain, HN-56, having an activity of d-glucose isomerization was isolated from soil, and was identified to be similar to Aerobacter aerogenes (Kruse) Beijerink. d-Glucose-isomerizing activity was induced when HN-56 was precultured in the media containing d-xylose, d-mannose, lactate, especially d-mannitol. Paper chromatography showed that the ketose formed in reaction system containing d-glucose was d-fructose alone. The optimum pH for the reaction was 6.5~7.0. Sulfhydryl reagents inhibit the reaction, but metal inhibitors affect little if any. With the washed living cells as enzyme source, only arsenate could accumulate d-fructose. In addition, the cells grown with d-mannitol and d-mannose showed no activity of d-xylose isomerase.     

深海趋磁细菌研究

介绍了趋磁细菌的基本概念及研究状况,综述了海洋趋磁细菌的研究进展,着重总结了深海趋磁细菌的研究成果及现状,展望了深海大洋和海山生态环境中趋磁细菌的研究意义及前景,为海洋趋磁细菌研究提供借鉴与参考。