- Volume 22, Issue 2, 1960

SUMMARY: Oligotrich protozoa from the sheep rumen, principally Entodinium caudatum, were maintained in culture in vitro and dividing every 2 days at a density of 15,000–30,000 protozoa/ml. for 18 months on a medium of rice starch, dried grass, 10% (v/v) rumen fluid (fresh or autoclaved) and 50 μg. chloramphenicol/ml. The effect on these organisms of varying each of these factors in turn and the use of different growth conditions is described. The protozoa have also been grown from an inoculum of 100’900/ml. to a density of over 50,000/ml. in 10 days.

SUMMARY: A strain of Arthrobacter globiformis grew on a glucose + ammonium + salts medium (pH 7) when this was supplemented with biotin (10−8 m). Maximal and most rapid growth was obtained by aerobic incubation in shaken culture at 30°. A variety of sugars, sugar alcohols, dicarboxylic acids, some amino acids and miscellaneous compounds could replace the glucose in this medium, but various aromatic compounds, purines, pyrimidines and other amino acids did not support growth, though several of these substances were oxidized by washed suspensions. The organism was an obligate aerobe whose terminal electron transport was mediated by a cytochrome system. Enzymic analysis showed that glucose could be metabolized by the hexose monophosphate oxidation and Embden-Meyerhof pathways. No direct oxidation of glucose to gluconic and 2-oxogluconic acids, and no Entner-Dou- doroff pathway for the utilization of 6-phosphogluconate were demonstrable. Studies with differently [14C]-labelled samples of glucose confirmed these findings and showed that in suspensions of organisms depleted of endogenous metabolites, the Embden-Meyerhof pathway was fully functional, accounting for c. 65 % of glucose utilization, the remaining 35 % proceeding by way of the hexose monophosphate cycle. The pyruvate so formed was normally further oxidized by the tricarboxylic acid cycle. The growth yield of A. globiformis on limiting amounts of glucose was no greater than that of Escherichia coli under the same condition. These observations are considered in relation to the allocation of A. globiformis in the autochthonous group of soil micro-organisms.

SUMMARY: A method of collecting unordered asci of Neurospora crassa makes use of the natural ejection of the ascospores from perithecia in groups of eight. Genetic evidence from 2374 groups shows that they were derived from individual asci. The method is reliable and efficient.