嘧啶核苷类物质乳清酸产生菌的选育

以谷氨酸棒杆菌JSIM-201菌株为出发菌株,通过紫外线和甲基磺酸乙酯诱变处理,得到了一株尿嘧啶营养缺陷型突变体U-12菌株,能以葡萄糖为碳源,硫酸铵为氮源,在发酵液中积累一种紫外吸收物质。对U-12菌株的发酵液分离提取结晶,经物理、化学分析鉴定,证明是乳清酸物质。发酵液中积累乳清酸8．6g/L。     

Effect of sodium dodecylbenzenesulfonate and antifoaming agents on the endonuclease activity of Serratia marcescens

The effect of sodium dodecylbenzene sulfonate (sulfonol) and certain froth breakers on the activity of endonuclease was studied in the cultural broth of Serratia marcescens in order to find out whether sulfonol could be used for limiting the infection. Sulfonol was found to have no effect on the cultural growth; it increased the activity of endonuclease in the cultural broth, and the peak of the activity appeared earlier than in the control medium. Propanol B-400 was shown to be the best froth breaker.     

利用肌苷发酵废液生产酵母的研究

本课题筛选了适宜在肌苷发酵废液中生长的酵母菌,从中选出了生长量最大的ＣＦ菌。并对利用肌苷发酵废液生产该酵母的条件进行了初步研究。     

Kinetics of Candida lipolytica yeast growth and biosynthesis of alpha-keto acids with thiamine deficiency in media with different carbon sources

The growth kinetics of Candida lipolytica on glucose, acetate and hexadecane was studied in batch cultures at thiamine deficiency. The growth at the deceleration phase is of a linear character. The transition from the exponential phase to the linear one is accompanied with the accumulation of alpha-keto acids in the cultural broth, which is also observed in the stationary phase. The rate of acid production in the linear phase increases as the specific growth rate decreases, and reaches the maximum value in media with different carbon sources at mu = 0.01--0.06 h-1. Apparently, the deceleration of growth is due to a decrease in the activity of a thiamine-dependent enzyme (pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase or transketolase) which is a limiting point of biosynthetic processes. Here, a linear growth is determined by the constant activity of this enzyme per unit volume of the cultural broth which, in turn, depends on the constant concentration of the coenzyme, thiamine diphosphate, in the same volume.     

Increased Sensitivity of Immunofluorescent Assay for Salmonella in Nonfat Dry Milk

The necessity of developing a quick, sensitive, and reliable test for Salmonella in nonfat dry milk (NDM) is evident from the recent tracing of Salmonella outbreaks to this product. Normally, coagulation of casein occurs when assaying NDM under regular cultural conditions, raising the possibility of trapped bacteria. After 20 hr of incubation of NDM in preenrichment lactose broth, enrichment was achieved by using Selenite-Cystine Broth. Smears from the enrichment broth were examined by the fluorescent-antibody technique (FAT) with a commercially available polyvalent O globulin conjugated with fluorescein. Standard cultural methods (SCM) were performed for comparison with FAT. Sensitivity of FAT was definitely improved by the use of trypsin. Casein coagulation of NDM can be avoided by addition of trypsin to samples during initial preenrichment in lactose broth. Samples containing approximately one Salmonella per 10 g were easily detected by FAT with the use of trypsin-treated samples. The method required only 42 hr to complete. Additionally, the use of trypsin enhanced recovery of Salmonella by use of SCM, as evidenced by alteration in the observed coliform to Salmonella ratios.     

Fibrinolytic activity of Bacillus mesentericus strains

Two Bacillus mesentericus strains with a high activity of proteolytic enzymes having the thrombolytic action were selected from a group of its collection strains. The effect of different carbon sources on the synthesis of proteases was studied. A growth medium containing potato broth (10%), peptone (0.5%) and lactose (0.5%) allowed one to obtain a cultural broth dissolving human blood clots within 2.5 to 3 hours in experiments in vitro.     

Formation of acetoin by Actinomyces olivaceus cultures]

Actinomyces olivaceus and some other actinomycetes accumulate acetoin and 2,3-butanediol in the cultural broth. Addition of cobalt to the medium favours the accumulation of acetoin.     

Determination of optical activity of the growth medium as a method for detection of extraterrestrial life]

Determination of optical activity of the cultural medium can be used for detection of extraterrestrial life. The composition of the growth medium depends on the duration of the experiment. Automatic biological stations are sent to planets for a short time, and the best components of the growth medium are D-glucose and D-maltose; optical activity of the cultural broth disappears upon assimilation of these compounds. Tartaric acid is less suitable since the duration of the experiment increases several times and desert soils do not always contain microorganisms assimilating tartaric acid.     

Effect of the culture broth on the reactivation of refractile resting forms and on spore germination in Bacillus cereus

The filtrate of the cultural broth taken at the lag phase of Bacillus cereus 504 growth stimulated the germination of endospores and the reactivation of refractile resting forms. The energy processes were shown to be stimulated in the studied anabiotic cells.     

Naphthalene oxidation by a Pseudomonas putida strain carrying a mutant plasmid

Naphthalene oxidation by a parent and a mutant strain of Pseudomonas putida was studied. The parent strain contained a plasmid NPL-1 which controlled oxidation of naphthalene to salicylic acid and was capable of oxidizing salicylate. The mutant strain did not oxidize salicylate because of a mutation in salicylate hydroxylase; it contained also a mutant plasmid NPL-41 which determined constitutive synthesis of naphthalene oxygenase. Salicylic acid which accumulated as a product of naphthalene catabolism in the cultural broth of the wild strain was found to undergo further oxidation by the population of growing cells. The content of salicylic acid in the cultural broth of the mutant strain reached maximum and then remained constant. An anion-exchange resin was tested in order to prevent the inhibition of naphthalene oxygenase by salicylate and to increase the yield of salicylic acid. The transmissible character of the mutant plasmid NPL-41 makes it possible, with the aid of conjugation, to construct Pseudomonas strains which would oxidize naphthalene to salicylic acid without further degradation of this compound.     

Possibility of detecting pyocyanine in Pseudomonas aeruginosa cells

Pyocyanin can be detected in the cells of Pseudomonas aeruginosa using UV and IR spectroscopy of disturbed complete inner reflection (DCIR). Intact cells of the parent strain liberating the pigment into the cultural broth and mutant cells lacking the ability contain pyocyanin within the cells. Occasionally, pyocyanin can be detected in the outer layers of the cells, which is more typical of the parent strain. In the freshly isolated fractions of the parent strain cellular walls, pyocyanin seems to be pesent in the bound state that has changed significantly its structural organization. In due course, the hypothetical complex pyocyanin--cellular wall decomposes to yield an "oxidized" pigment similar to that liberated into the cultural broth. the cell wall of the mutant possesses the properties of "oxidized" pyocyanin immediately after isolation of the fraction. The pigment cannot be identified in the fractions of cytoplasmic membranes; pyocyanin is present in the "oxidized" state in the fractions of cytoplasm for the cells of both types. The paper discusses the role of the permeability of cytoplasmic membranes in the transport of pyocyanin from the cytoplasm into the cellular wall of the bacterium and then into the surrounding medium.     

Extracellular polysaccharides in yeasts of the genus Sporobolomyces Kluyver et van Niel]

Nineteen yeast strains belonging to the genus Sporobolomyces were tested for the ability to produce extracellular polysaccharides during submerged cultivation in a defined growth medium. These polysaccharides, accumulated by the yeast Sporobolomyces in the cultural broth, are a heterogeneous group of polymers.     

Comparison of methods for the recovery and detection of low levels of injured Salmonella in ice cream and milk powder

This study compared the ability of four rapid methods and a standard cultural method to detect low levels of heat-injured cells of Salmonella typhimurium in ice cream and skimmed milk powder. The detection of Salmonella in samples contaminated with low levels (< 10 cfu 25 g-1) was significantly greater with the novel broth method than with the other methods (P 10 cfu 25 g-1, there was no significant difference between the methods except for the novel broth method and a dipstick-based immunoassay (P 相似文献   

The separation of true coagulases from other enzymes of the extracellular proteolytic complex of Aspergillus ochraceus by using affinity chromatography]

A complex of proteases has been isolated from the cultural broth of fungi Aspergillus ochraceus HP-19 by precipitation ammonium sulfate. Using the method of affinity chromatography on the biospecific sorbents the conditions for separation of proteases into ones with coagulase activity and with fibrinolytic activity have been found.     

EVALUATION OF CULTURE PROTOCOLS AND OXYRASETM SUPPLEMENTATION FOR ARCOBACTER SPP.

Growth of Arcobacter butzleri was evaluated in Brain Heart Infusion broth incubated aerobically, microaerobically, and with Oxyrase^TM supplementation (anaerobically). At initial concentrations of10¹ to 10³ cells/mL, A. butzleri populations reached 7.5 to 8.0 log CFU/ml in 48h at 37C in Oxyrase^TM -supplemented broth. The organism quickly declined in the other two systems to undetectable levels during the initial 24h of incubation. Only moderate population levels (ca. 3 log CFU/ml) could be detected in aerobic and microaerobic systems after 56h incubation. Growth of five Arcobacter spp. strains was evaluated at 30C in Brucella-blood broth, modified Cary and Blair Transport Medium, and a biphase cultural system. Strains were inoculated at a level of ca. 10³ cells/ml and incubated with and without Oxyrase^TM supplementation to the system for 36h. Both the Brucella-blood broth and the biphase system supported good growth of the strains, with counts reaching ca. 8 to 9 log CFU/ml. Modified Cary and Blair Transport Medium was the least effective cultural system. Oxyrase^TM provided slight to moderate stimulation of growth for most strains.     

Studies on the amino acid fermentation. Part 1. Production of L-glutamic acid by various microorganisms

Screening tests for glutamate producing strains were carried out, with the media containing carbohydrate and ammonia source as chief ingredients. Glutamate as well as certain other amino acids was detected by paper chromatography in culture broth of many microorganisms tested. Accumulation of L-glutamate in a significant amount (at least a few mg of glutamate per ml of broth) has been demonstrated by various strains of bacteria, streptomycetes, yeasts, and fungi. The highest level of glutamate production has been obtained by a new species of Micrococcus, yielding as much as 0.25 mole of it from one mole of glucose. The courses of fermentations mainly by known strains of microorganisms are shown. The importance of the cultural condition and strain specificity for the production of amino acids are briefly described.     

Macromolecular subunits on the surfaces of the cell wall of Thiocapsa roseopersicina]

A layer of fungiform macromolecular subunits was found on the surface of the cell wall of Thiocapsa roseopersicina, a purple sulphur bacterium, strain BBS. The cap of a particle has a diameter of 40 to 60 A; the stalk is 80 to 100 A long and 20 to 30 A thick. Under the conditions of nitrogen fixation and a low content of vitamin B12 (0.1 mcg/litre) in the cultural broth, a second layer of similar particles is formed over the first layer.     

Isolation and study of the biological properties of a protease biosynthesis stimulating factor in an associative fungal culture

A factor stimulating the production of exoproteases by Aspergillus kanagawaensis both in a single culture and during combined cultivation with Aspergillus wentii was isolated from the cultural broth of a component in the microbial association according to our scheme. The factor is a pigment of the hydroxyanthraquinone nature. It made the enzyme biosynthesis increase 3.7 times. Its effect on the biosynthesis was compared to that produced by other anthraquinone pigments, viz. alizarin, rubomycin and cinerubins. The compounds stimulated the biosynthesis only 2 to 2.5 times.     

Salmonella identification after incubation in the soil

We have tried to study the fate of Salmonella strains in soil. We have looked at their biochemical modifications during their evolution to dormant state and during their reviviscence. The beta galactosidase which is negative in the parent strain became positive after two weeks of cells starvation in soil. Stressed cells became able to produce acetoin. Some stressed cells did not produce the lysine decarboxylase, which is positive in parent cells. These modifications are reversible and depend on cultural conditions. Incubation of stressed cells in nutrient broth for more than four weeks helped them to reverse to normal forms. Simultaneous search for atypical Salmonella was done in dissect sludge of a domestic wastewater treatment plant and in soil irrigated with treated water. Atypical strains of Salmonella are found. We have seen that, after incubation in nutrient broth for more than four weeks, atypical strains characters evolved generally to their parental characters. All modifications of Salmonella in soil samples can make their identification very difficult and perhaps impossible.     

Production of α-Glucosidase and Its Role in Regulation of Amylase Production by Bacillus circulons F-2

Bacillus circulans F-2 requires a special carbon source or cultural conditions for amylase production. The α-glucosidase production of this bacterium was studied in various cultural conditions with measured glucose concèntrations. High amylase production was always accompanied by low α-glucosidase production and the absence of glucose in culture broth. Usually higher α-glucosidase production was observed in cultural conditions where little amylase was produced. In the presence of 1-deoxynojirimycin, an inhibitor of α-glucosidase activity, the bacterium produced significant amounts of amylase even in conditions giving high α-glucosidase production. It was concluded that the special requirement of this bacterium to produce amylase is effected by its high sensitivity to glucose repression and by the production of α-glucosidase which leads to the formation of glucose. Production of α-glucosidase was, like that of amylase, induced by maltooligosaccharides and repressed by glucose, but both its induction and repression are less sensitive to glucose than those of amylase.