Experiments were directed towards the production of high biomass concentrations in cultures of Methylococcus capaulatus. In shake flasks the effects of ammonium ion, phosphate ion and various trace metals on growth were studied. I n the chemostat the effects on growth of methane limitation, oxygen limitation, aeration, dilution rate, pH value and temperature wore studied and carbon balances were made in steady state conditions. Growth in the fermenter was stimulated by the use of Amberlite CG-120 ion exchange resin in the medium. The probability that Amberlite removed a growth inhibitor is discussed.MANY NEW SPECIES of methane-utilizing bacteria have been isolated in the past few ymrs (Whittenbury, Phillips & Wilkinson, 1970). The possibility of producing single cell protein from natural gas is attractive, but the economics of such a process are speculative because we lack precise information on factors governing growth of these organisms. This lack probably reflects the considerable technical difficulty in growing pure cultures of these bacteria. Our work is concerned with the growth of one species of methylotrophic bacterium, Methylococcus cupsulatus, in shake flasks and in continuous chemostat culture and presents new data on factors influencing the production of biomass and the stoichiometry of methane oxidation. Materials and Methods OrganismThe strain of M . capsulatus isolated by Foster & Davis (1966) was used. Stock suspensions were kindly supplied by Professor J. R. Nonis, Shell Research Limited, Broad Oak Road, Sittingbourne, Kent. HediumThe liquid medium (T4) used both in shake flasks and in continuous culture was made up in 3 parts, A, B

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SUMMARY The influence of 3 types of compounds (L‐amino acids, carboxylic acids and sugars) on the growth of Methylococcus capsulatus in Petri dishes was investigated. Increase in colony diameter was used as the growth parameter. L‐amino acids and carboxylic acids which are normal metabolic intermediates prevented growth in low concentrations. Threonine, leucine, histidine and glycine were especially inhibitory; c. 0.01% was sufficient to suppress growth completely. Glutamic acid at 0.1 % concentration completely suppressed growth but at 0.005% markedly stimulated growth; similar effects were shown by lysine, methionine, glutamic acid, tryptophane, tyrosine, proline and citric acid. Among the sugars, glucose was the most potent growth inhibitor; maltose and sucrose had practically no effect.

Resistance (R) factor-mediated streptomycin (Sm) resistance differs from classical, high-level, chromosome-borne Sm resistance in its dominance over sensitivity and in the level of its effectiveness (in Escherichia coil-25 pg/ml versus >2,000 jg/ ml). In addition, an R factor-containing strain, unlike high-level Sm-resistant bacteria, showed an inoculum effect with respect to its level of Sm resistance. Crude extracts of this strain destroyed the inhibitory activity of Sm and bluensomycin (Blue) on in vitro protein synthesis. The ribosomes from this strain proved to be sensitive to Sm in vitro. The requirements for in vitro inactivation of Sm (and Blue) were determined to be: extract, adenosine triphosphate or deoxyadenosinetriphosphate, and Mg+. Chromatographic techniques with radioisotopes revealed the formation of an inactivated form of Sm containing adenosine (or deoxyadenosine), phosphate, and Sm in equimolar amounts. The adenylate moiety is coupled to the streptobiosamine residue, rather than to the streptidine ring, of the Sm molecule. The adenylating enzyme, which is not induced by Sm, is located in the periplasmic space of the R factor-containing strain.