No abstract

No abstract

Since Schroeter (1872) first isolated and described an organism producing a green-fluorescent pigment, information on this particular type of organism has consistently appeared in the literature. RfiAi6ka (1899) studied a small group of fluorescent organisms and concluded that the group could be separated into two parts, one closely related to the semi-pathogenic Bacterium pyocyaneum, the other to Bacterium fluorescens-liquefaciens. A study of 15 organisms convinced Niederkorn (1900) that there were only two constant species. Jordan (1903) separated 58 strains into two groups on the basis of gelatin liquefaction. Edson and Carpenter (1912) separated 42 strains, isolated from Vermont maple sap, into seven groups, on the basis of hydrogen sulphide production, reduction of nitrates, growth on Uschinsky's solution, growth on Cohn's nutrient solution and action on gelatin and milk. They concluded that representatives of the seven groups plus six other species can not be sufficiently well differentiated to warrant calling them other than "liquefaciens" or "non-liquefaciens" strains of Pseudomonas fluorescens. Tanner (1918) found in the literature more than 95 species, many of which were incompletely described. He placed 100 strains which he isolated from water into 27 groups. However, he suggests that gelatin liquefaction and nitrate reduction are sufficiently variable to limit his groups to nine. Sherwood, Johnston and Radotincky (1926) presented incomplete data on 22 strains of Bacillus pyocyaneus, giving data on carbohydrate reactions, hydrogen sulphide, indole, and hydrogen cyanide production, and nitrate reduction. Monias (1928) divided 30 strains into five groups; however, only three of his groups produced pigment. These three groups were formed on the basis of morphology and carbohydrate fermentations. Reid, Harris, Naghski and Gatchell (1941) studied 600 Pseudomonas cultures and found in addition to serological differences two types of flagellation and a difference in the ability to grow at 370C. Early investigations indicated that pigmentation was inconsistent. Gessard (1890) reported that various cultural methods caused Bacillus pyocyaneus to form the fluorescent pigment alone, pyocyanin alone or both pigments together. Charrin and Phisalix (1892) recorded the failure of pigment production by growing BaciUus pyocyaneuqs at 42.5°C. Jordan (1899) suggested: "Except for the occasional loss of one or another function, the different varieties are not so platic as sometimes assumed and can not be readily converted into one or another by subjection to varying conditions of life." Eisenburg (1914) found that seven stock cultures varied in pyocyanin and fluorescin production. Baerth-491

The conception of a definite period of youth in the life of bacteria now appears to be well established. From the standpoint of the initiation of reproduction in cultures it has long been known that transplants from cultures only a few hours old start reproduction at once, whereas inoculations from old laboratory cultiures require a period of dormancy before reproduction begins. This phenomenon was observed microscopically by Barber (1908), and was later studied more in detail with the aid of growth curves by Penfold (1914) and Chesney (1916). From the work of Clark and Ruehl (1919) and Henrici (1921) it is known that the morpholog of bacterial cells varies greatly with the age of the culture. Henrici has carefully studied this subject and the biological significance of these morphologic changes has been interpreted by him in a series of subsequent papers (1928). Sherman and Albus (1923) studied young and old bacterial cells with the idea of detecting physiological differences. A number of tests were found which revealed definite physiological distinctions between young and mature cells. Differences were observed with respect to acid agglutinability, and resistance to harmful environmental factors, such as extremes of temperature, germicidal substances and osmotic pressure. These workers concluded that a period of physiological youth is characteristic of bacterial cells.

No abstract