No abstract

SUMMARY: T w o hundred and ninety-six strains of mesophilic species of the genus Bacillus were isolated from soil and examined for the characters described principally by Smith, Gordon & Clark (1fkW) as well as for some additional characters. T w o hundred and forty-six belonged clearly to named species in the classification of Smith et al., thirty-two strains were clearly intermediate between two species and eight strains remained unallocated. In addition, eleven other strains appeared to represent a previously undescribed species (Proom & Knight, 1950 The strains of B. pasteurii were the most heterogeneous in their nutritional requirements, the components ammonium ion, amino-acids, aneurin, biotin and nicotinic acid being involved. All strains required amino-acids and aneurin ; in addition, biotin or nicotinic acid and sometimes ammonium ion were required, depending on the particular strain.There are few records of wide comparative surveys of bacterial genera which have made use not only of the classical bacteriological distinguishing tests and methods, but which have also included determinations of exact nutritional requirements, and of metabolic and serological-characters. Intensive studies of particular species from these aspects have been somewhat more common; but even here comparative studies of numerous strains or clones of a species, when made, have only seldom included all the features noted above, so that well-rounded pictures of their biological properties are infrequent. The Culture Collection at these Laboratories, with the staff and services necessary for its maintenance and development, offered an opportunity to make comparative It was hoped that such comparative surveys might yield information which would help to improve the diagnosis, differentiation and classification of bacteria as they came to hand. It was further hoped that from this material might come indications of natural relationship, thus helping to make classifications somewhat less arbitrary than they tend to be at present. A long-term objective is to accumulate information which might contribute to the study of taxonomic and evolutionary problems. This is not the place to discuss the problem of species differentiation; some pertinent examples will appear in the sequel. Indeed it might be well at this point to state our standpoint in this respect. We believe that the question of species definition and differentiation among bacteria is best not argued as a metaphysical question, apriori as it were, but that the question of classification will be better worth discussion only when much more pertinent material is available. It is part of the purpose of the present work to supply some of this material. It is, of course, true that for practical purposes distinguishing characters, however empirically determined, are invaluable and that a t least empirical classifications do have to be made for current use. But this does not preclude a desire to achieve better classifications, which will presumably be the better the more closely they reflec...

UNTIL recently the specific toxic substances produced by bacteria have been investigated mainly by pathological and serological methods and further knowledge of their chemical nature and modes of action is clearly desirable. In

IN the course of our analysis of the nutrients of Streptococcus haemolyticus it was found that growth did not take place in a mixture containing peptone,

HITHERTO Staphylococcus aureus has not been grown in media of completely known chemical composition. With a medium in which most of the nutrients were known (amino-acids and glucose) it has been necessary to add a supplement, quantitatively very small but qualitatively essential, before growth can occur. The necessity for the supplement was first shown by Hughes [1932] and later by Knight [1935], who used autolysed yeast extract (marmite) as a rich source of the growth factor and acid-hydrolysed gelatin plus glucose as the deficient basal medium. Subsequently it was found possible [Fildes et al. 1936] to substitute a collection of amino-acids plus glucose for the gelatin hydrolysate basal medium. The present paper shows that the active concentrate from yeast obtained by Knight, which must be given to S. aureus for growth to take place, can be replaced by nicotinic acid and vitamin B1 together, neither alone being effective.It is therefore now possible to grow a typical strain of S. aureus on a medium containing only known chemical components.