The major cell wall amino acids and sugars in 177 strains of coryneform bacteria were determined using a ‘rapid’method. Representatives were examined for free mycolic acids and the oxygen requirements of all strains were determined. Included were named strains, most of which were labelled Arthrobacter, Brevibacterium, Cellulomonas, Corynebacterium or Microbacterium, and a similar number of unnamed isolates from various natural sources. Strains which contained meso‐diaminopimelic acid (DAP) were divided into four groups according to their oxygen requirements, the wall sugars and the occurrence and nature of free mycolic acids. Group 1 strains were mainly facultatively anaerobic and contained arabinose and mycolic acids of the Corynebacterium type. They were considered to be members of Corynebacterium sensu stricto and included Cor. diphtheriae and related animal parasites, Microbact. flavum, and Cor. glutamicum and similar species. Group 2 strains were aerobic, contained arabinose and mycolic acids of the ‘rhodochrous’type and were considered members of the ‘rhodochrous’complex. Group 3 strains were aerobic, contained ribose and no mycolic acids. Most were Br. linens strains from cheese but a few, possibly related strains, were from other habitats. Group 4 strains were aerobic and contained neither a pentose sugar nor mycolic acids and were of unknown taxonomic status. Most remaining strains contained lysine or ornithine in the wall and smaller numbers contained L‐DAP or diaminobutyric acid; none contained mycolic acids. The chemotaxonomic data are discussed in relation to recent numerical taxonomic studies of coryneform bacteria.

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Present address : Bacteriology Department, The Royal Victoria Infirmary, Newcastle.upon-Tyne 1. Materials and Methods(a) Sources and isolation of strains The new isolates were obtained from a garden soil (pH 6.7), a field soil (pH 6.5) and freshly cut herbage from a lawn. Each sample was a composite of several taken from different parts of the field or plot and was plated on various 'nonselective' media chosen to give the highest possible viable counts. About 50 colonies were picked from suitable high dilution plates of each medium so that a representative collection of the Merent nutritional types p r m n t would be obtained. Three kin& of plating media were used. Medium TA WM similar to that used by Topping (1937) and contained: peptone, 2-5 g; yeast extract, 2.5 g ; agar, 20 g ; demineralizedwater, 11. Medium TSXA was similar in composition to medium TA but contained 25% (v/v) of soil extract. Plain soil extract agar medium was also used. At an early stage of the work Evans peptone and Yeastrel (yeast extract) were used in media; these products were later replaced by Bacto-peptone (Difco) and Bacto-yeast extract (Difco). All media were sterilized at 121" for 15 min and had a h a 1 pH value of 6.8.Decimal dilutions of the soil samples and of a suitable macerate in the caae of Coryneform bacteria : cell walls and nutrition '9 herbage were made in quarter strength Ringer's solution. Pour plates were prepared in triplicate and incubated at 25" for 21 days in air.Colonies were transferred into a semisolid agar medium (TSXss) similar in composition to medium TSXA but with an agar concentration of 0.2%

The nitrogen nutrition of 93 strains of soil and herbage coryneform bacteria and 16 named strains of Arthrobacter and Cellulomonas was examined. I n testing for the ability of coryneform bacteria to utilize inorganic nitrogen as sole nitrogen source it was found necessary to use a medium containing a balanced mineral base and a suitable metal chelating agent in order to obtain reproducible results. A suitable medium is described. When provided with essential vitamins, 90% of soil isolates utilized inorganic nitrogen as sole nitrogen source while only 30% of herbage isolates did so. Sixty per cent of herbage isolates utilized inorganic nitrogen as major nitrogen source when provided with L-methionine in addition to vitamins, whereas no soil isolate showed a requirement for methionine. For a small residue of strains from each habitat the substrate nitrogen requirements were not determined. Of the named strains examined A . terregens utilized inorganic nitrogen as major nitrogen source when provided with methionine and vitamins while the remainder utilized inorganic nitrogen as sole nitrogen source. For 4 Arthrobacter spp. the nitrogen requiiements described differ from those previously reported.

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