THE SELECTIVE ACTION OF THALLOUS ACETATE FOR LACTOBACILLI

SUMMARY: The effect of thallous acetate has been examined on the growth of 23 strains of lactobacilli representing 13 different species. All strains grew satisfactorily in both broth and agar media containing 0.1% of thallous acetate. Of the 18 other organisms also examined the growth of the streptococci was unsuppressed, staphylococci, a micrococcus, B. licheniformis and Pr. mirabilis were partially inhibited and strains of Bact. coli, B. cereus, Chr. prodigiosum and Ps. fluorescens were almost completely inhibited by that concentration. By its use a valuable selective medium for isolating lactobacilli from natural habitats of mixed flora was obtained, other organisms, with the exception of streptococci, being almost completely eliminated.     

天然药物对血链球菌生长和产酸影响的体外研究

目的：通过研究不同天然药物对血链球菌生长及产酸的影响,为今后筛选出能有效调理口腔菌群生态平衡的药物奠定基础。方法：选用变形链球菌SB179作为实验菌株,测定川芎,血藤,五倍子等11种天然药物的最低抑菌浓度MIC,再以低于MIC的4个浓度配制含药的TPY液体培养基,调定其初始pH为7．4,接种血链球菌,厌氧培养后测定其终末pH,结果：当药物浓度低于或等于8．000mg/ml时,各天然药物对血链球菌的生长均有一定的抑制作用,且以五倍子作用较强,槟榔,茶多酚,蜂房,大黄,三七,血藤,白芷对血链球菌的产酸具有一定的抑制能力,而黄芩,川芎,五倍子和儿茶没有明显的抑制作用,结论：槟榔,茶多酚,蜂房,大黄,三七,血藤和白芷对血链球菌的生长和产酸都有一定的抑制作用.     

天然药物对唾液链球菌生长与产酸影响的体外研究

目的：通过研究不同天然药物对唾液链球菌生长及产酸的影响,为今后筛选出能有效调理口腔菌群生态平衡的药物奠定基础,方法：选用唾液链球菌SS196作为实验菌株,测定川芎,血藤,五倍子等11种天然药物的最低抑菌浓度MIC,再以低于MIC的4个浓度梯度配制含药的TPY液体培养基,调定其初始pH为7．4,接种唾液链球菌,厌氧培养后测定其终末pH,结果：当药物浓度低于或等于8．00mg/ml时,除槟榔,蜂房,三七外,其他药物对唾液链球菌的生长都有一定的抑制作用,且以大黄,五倍子和黄芩较强,槟榔,茶多酚,大黄,蜂房,黄芩,三七,五倍子和儿茶对唾液链球菌的产酸具有一定的抑制能力,而白芷,川芎和血藤没有明显的抑制能力,结论：茶多酚,大黄,黄芩,五倍子和儿茶对唾液链球菌的生长和产酸都有一定的抑制作用。     

A NOTE ON THE SIMILARITIES BETWEEN THE CURVES OF GROWTH AND OF REGENERATION

The curves of growth and of regeneration follow the same course, and can be represented by the same exponential equation. This is taken to substantiate the theory that growth and regeneration are essentially identical processes governed by the same laws. A common peculiarity of the curves of growth and of regeneration is that during a short period in the early stages of regeneration and of growth, the apparent observed speed of these processes seems to be relatively slow. As a result, the curve of the fitted equation cuts the time axis not at zero, the beginning of growth or regeneration, but somewhat later. Data on regeneration are cited indicating that the initial slow phase of regeneration is due to the time required for the formation of a cap of embryonic cells which serves as a basis for the more active later regeneration; in other words, to qualitative growth which cannot be expressed in terms of quantitative units. It is suggested that the apparent initial slow phase of growth of the individual from the fertilized egg is due to a similar qualitative growth. It is suggested that if the initial qualitative changes could be converted into some common unit with the subsequent quantitative changes, the apparent initial lag would disappear, and the exponential equation representing the course of these processes would then be the same as the equation used to represent the course of a monomolecular chemical reaction. Certain implications of this reasoning are discussed in the text.     

EFFECTS OF ACETATE ON THE GROWTH AND CHLOROPHYLL CONTENT OF GOLENKINIA1

Growth and chlorophyll synthesis by the green alga Golenkinia cease after approximately 60-hr incubation in 0.01 M sodium acetate. These effects are immediately preceded by a rapid rise of the pH of the medium to 8.6–8.8 due to acetate uptake. The pH kinetics are due to a gradual loss of the phosphate buffer, not to the induction or activation of acetate assimilatory enzymes. However, neither high pH nor sodium acetate alone is sufficient to inhibit cell division and bleach the algae; both must be present. Additional experiments support the hypothesis that acetate alters the cells so that they become sensitive to high concentrations of OH^? ions.     

A NOTE ON THE USE OF ROGOSA AND MODIFIED ROGOSA MEDIA FOR THE ENUMERATION AND CULTURE OF LACTOBACILLI

SUMMARY: The modified Rogosa media (acetate broth and acetate agar) developed by Mabbitt & Zielinska (1956) have been compared with tomato juice media for the growth of representative Lactobacillus species.
Most of the species tested grew markedly better in acetate broth than in tomato dextrose broth, but some cultures did not grow well in the acetate broth although they grew normally in tomato dextrose broth. The acetate agar was satisfactory for counting those lactobacilli cultured at 30° but was inferior to tomato dextrose agar for counting those grown at 37°.     

THE ASSOCIATED GROWTH OF STREPTOCOCCUS LACTIS AND ESCHERICHIA COLI

SUMMARY: The possibility that contamination of farmhouse starters by coli-aerogenes bacteria may be a factor in producing the subtle flavour of farmhouse Cheddar cheese has been discussed. The associated growth of Strep. lactis and E. coli I at 30° and 37° resulted in the rapid disappearance of E. coli from the mixtures, even though it had been the dominant organism in some of them originally. Mixtures containing Strep. lactis and an anaerogenic strain of E. coli still contained this variant at the end of a month, although in no definite ratio and in a very much reduced proportion. It is concluded that the components of coli-lactic starters to be used in the manufacture of cheese should be combined together in the vats.     

THE PHYSIOLOGICAL AND SEROLOGICAL PROPERTIES OF STREPTOCOCCUS BOVIS AND RELATED ORGANISMS ISOLATED FROM CATTLE AND SHEEP

The physiological and serological properties of 153 strains of Streptococcus bovis isolated from cattle and sheep have been studied. With 12 specific antisera it was possible to type 75 of the isolates. Neither the fermentation of arabinose nor of raffinose was related to type specificity. The only strain fermenting mannitol was serologically distinct from all the other strains, and the type antigen was probably located on the cell wall whereas with the other 11 types it was capsular.
The distribution of these types in cattle and sheep has been determined together with their changes in individual cows sampled on three occasions over 18 months.     

乙酸积累对基因工程菌培养的影响及与培养基pH的关系

在rIL-2工程菌K_(802)(pLY—4)高密度培养中,发现培养液中有大量代谢副产物乙酸积累,乙酸的存在对工程菌的生长和产物的表达均有明显的抑制作用,这种抑制作用是制约工程菌高密度培养的重要因素。为了减小这种抑制作用,初步研究了培养基pH与乙酸抑制作用的关系,发现适当提高培养基pH值,能减小乙酸的抑制作用;高密度培养时,提高培养基的pH后,虽然仍有大量乙酸积累,但产物的表达水平和菌密度都有提高。     

墨兰原球茎生长的研究

以墨兰种子胚经培养诱导萌发形成的原球茎为材料,研究其生长的最适条件。结果表明：最佳基本培养基是ＭＳ培养基;ＮＡＡ０．５ｍｇＬ＋ＢＡ１．０ｍｇＬ－１有利于生长和分化;在培养基中加入１％蔗糖和０．１％活性炭最有利于原球茎生长;ｐＨ５．０偏酸环境适合于生长;每天给予１５．５ｕｍｏｌｍ－２Ｓ－１１６ｈ的光照最佳。如将上述单因子组合在一起,其原球茎鲜重增长率比对照（ＭＳ培养基）高４６％。在不同切割方式中,掰开法鲜重增长率比纵切法或横切法都高。