摘要:

The distribution of chloroform–methanol and alkali-extractable lipids in the cell walls of aerobically grown filamentous cells fromMucor rouxiihas been determined. The results have been compared with the corresponding lipid composition of yeast-like cells fromM.rouxii, which can be produced in two ways: by growth under anaerobic conditions and by aerobic growth in the presence of 0.22% phenethyl alcohol (PEA). It was observed that in most cases the crude cytoplasmic fraction contained higher levels of several lipids (i.e., squalene, sterols, triterpenes, and fatty acids) than did the corresponding cell walls. The cell walls did, however, contain both "free" (chloroform–methanol extractable) and "bound" (alkali extractable) lipids although the relative amounts were markedly dependent on the cell growth environment. The aerobically grown filamentous cell walls contained higher levels of squalene, sterols, triterpenes, and fatty acids than did aerobically grown yeast-like PEA-induced cell walls and there was also considerable variation in the "free''/"bound" ratios of the various lipid components. The lipid levels in both the cell walls and cytoplasm of the anaerobically grown cells were considerably lower than those of the cells grown under aerobic conditions. In addition, the differences in the growth environment were also reflected in the compositions of the individual lipid fractions from both the cell wall and the cytoplasm fraction.

ISSN:0008-4166    

DOI:10.1139/m75-011

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The fatty acid pattern inMycobacterium vaccaestrain JOB5 was examined after growth onn-alkanes (C14–C18), 1-alkenes (C14–C18), 2- or3-methyl octadecane, and 8-heptadecene. It was evident that monoterminal oxidation ofn-alkanes was followed by β-oxidation and that both parent fatty acid and products of β-oxidation were incorporated into cellular lipids. Radioactive experiments demonstrated that there was desaturation of long-chain fatty acids. There was no evidence of chain elongation. Growth on 1-alkenes resulted in the incorporation of fatty acids that were products of two primary modes of oxidation: (1) methyl group attack resulting in ω-unsaturated fatty acids and (2) double-bond attack resulting in the removal of one carbon from the substrate. Cells of strain JOB5 grown on 2- and 3-methyl octadecane contained the corresponding iso- or anteiso-fatty acids in significant quantity. Cells cultured on 8-heptadecene contained 8- and 9-heptadecenoic acids, 6- and 7-pentadecenoic acids, 9- and 10-methyl hep-tadecanoic acids, and 7- and 8-methyl pentadecanoic acids. Fatty acid composition (C13to C19) was affected by substrate chain length and was additionally modified by cellular control mechanisms.

ISSN:0008-4166    

DOI:10.1139/m75-012

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

In continuous-flow environments, such as a chemostat, we find that, in theory, stable mixed populations of competing species obeying Monod/Michaelis–Menten growth kinetics (extended to more than one limiting substrate) cannot coexist unless the number of growth-limiting substrates is equal to or greater than the number of species. Additional restrictions on the relative values of the growth-yield constants and input-substrate concentrations must also be satisfied. Examples of the theoretical growth of mixed cultures after initial inoculation in stable and unstable cases are presented. The ecological consequences of these findings are briefly discussed.

ISSN:0008-4166    

DOI:10.1139/m75-013

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

WhenAspergillus nidulansis grown with urea as sole nitrogen source it possesses about sixtold higher activity of mannitol-1-phosphate dehydrogenase than when it is grown with both urea and sodium nitrate.

ISSN:0008-4166    

DOI:10.1139/m75-014

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

An antibacterial substance produced by a strain ofStreptococcus mitior, and isolated from a human throat culture, was found to inhibit the growth of streptococci and staphylococci. The substance was characterized as hydrogen peroxide.

ISSN:0008-4166    

DOI:10.1139/m75-015

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

A bromocresol purple liquid indicator medium and an eosin – methylene blue agar have been developed for the demonstration and isolation of microorganisms able to degrade the chlorinated herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D). Plates of the eosin – methylene blue agar indicate individual 2,4-D-degrading bacterial colonies. Both indicator systems show the production of acid, presumably hydrochloric, during degradation of the 2,4-D in the media. Concentrations of 2,4-D required to give an acid reaction in media with varying concentrations of yeast extract were determined; the production of about 0.24 mmol of hydrochloric acid seems necessary to counteract the buffering effect of 100 mg of metabolized yeast extract. Acid production from the herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA), which in the salt form could yield only small amounts of hydrochloric acid, was inconsistent. The two indicator media should be useful in investigations of the microbial degradation of other acid-yielding halogenated pesticides.

ISSN:0008-4166    

DOI:10.1139/m75-016

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Growth characteristics of a facultatively halophilic strain ofMicrococcus, capable of growth in medium containing no added NaCl and in medium containing 5.5 M NaCl, were studied over a range of salt concentrations and temperatures. Optimal growth occurred at 35C in a medium containing 1.0 M NaCl. In a medium containing 0.1 M NaCl, growth only occurred if the incubation temperature was less than 30C. No growth occurred if KCl, LiCl, NH4Cl, MgCl2, or sucrose was substituted for NaCl at 35C. A reexamination of bacteria previously described as moderate halophiles is suggested.

ISSN:0008-4166    

DOI:10.1139/m75-017

出版商:NRC Research Press    

年代:1975

数据来源: NRC