Qualitative Studies of Soil Microorganisms: Xiv. Specific Vitamin Requirements of the Predominant Bacterial Flora

Abstract

A relatively high proportion of the indigenous bacteria of a field soil (27.1%, corresponding to 14.1 millions/g.) required one or more vitamins for growth. The vitamins found to be essential, either alone or with others, were, in order of frequency, thiamine, biotin, vitamin B12, pantothenic acid, folic acid, nicotinic acid, and riboflavin. In all, 16 different 'patterns' were noted for vitamin requirements, the number of vitamins needed by individual strains ranging from one to five. The findings point to the soil as an important habitat of vitamin-requiring bacteria, many of which show potentiality as assay organisms. Their occurrence in the numbers found indicates that growth-factors should receive equal emphasis with antibiotics in problems involving the microbial equilibrium in soil and interrelationships between the normal soil microflora, soil-borne disease organisms, and growing plants.

Comparative Carbohydrate Catabolism in Arthrobacter

“…Although many microbiologists felt that the soil globiform group ought not to be included in the genus Corynebacterium, the present taxonomic status of the genus Arthrobacter is still a subject of much controversy. Lochhead & Burton (1957) and Lochhead (1958), while investigating the dominant soil microflora, isolated and characterized several bacterial species, some of which require amino acids, others being dependent to different degrees upon growth factors. A few of these species were assigned to the genus Arthrobacter on the ground of morphological resemblance, in spite of pronounced differences in nutritional requirements.…”

Stimulation of Streptomycin-Resistant Bacteria in the Rhizosphere of Leguminous Plants

“…The bacteria from the rhizospheres and soil samples were grouped according to the method of Lochhead & Chase (1943) by testing whether they would grow on the following media: (a) Basal medium: glucose, 1.0 g.; K,HPO,, soil extract (prepared as above) +yeast extract 1.0 g./l. ; pH 6.8.…”

Effect of soil microorganisms on the growth of roots in rice seedlings

“…Considering the varied requirements for nutrients among Rhp-M., Rhs-M., and nRhs-M. (12,15), the following four media were prepared. C medium: S medium + glucose (l%)+casamino acid (0.4%) Y medium: S medium + glucose (I %) + yeast extract (0.1 %) CY medium: S medium + glucose (l%)+casamino acid (0.4%) + yeast extract (0.1 %) R medium: Rice root extract Rice root extract was prepared from the roots of rice seedlings by modified 011 et al's method (10).…”