Mzabimycins A and B, novel intracellular angucycline antibiotics produced by Streptomyces sp. PAL114 in synthetic medium containing L-tryptophan

Instability of growth characteristics and chloramphenicol production was observed during long-term continuous cultivations of a Streptomyces sp. The occurrence of these variations was attributed to a continuous population selection.Fermentation patterns are presented for growth in a complex and in a synthetic medium, at different replacement times. The culture degeneration pattern was influenced by the type of medium used and by the replacement time. A rich complex medium created the most favorable conditions for the maintenance of an antibiotic-producing population.Growth on the walls took place when cultures were grown in the complex medium with a fast replacement time. Under these conditions no decrease in chloramphenicol yield was observed, even after 76 replacements of the medium. Possibly a population closely related to the initial one was maintained on the walls, and thus replacement by non-producing populations was avoided. Application of this method is suggested as a means for maintenance of culture stability in continuous industrial fermentation.

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Influence of nitrogen source on formation of chloramphenicol in cultures of Streptomyces sp. 3022a

Canadian Journal of Microbiology ◽

10.1139/m68-098 ◽

1968 ◽

Vol 14 (5) ◽

pp. 587-593 ◽

Cited By ~ 4

Author(s):

D. W. S. Westlake ◽

F. Sala ◽

R. McGrath ◽

L. C. Vining

Keyword(s):

Nitrogen Source ◽

Antibiotic Production ◽

Synthetic Medium ◽

Nitrogen Sources ◽

Special Role ◽

Fermentation Time ◽

Streptomyces Sp ◽

Physiological Conditions ◽

Production Studies ◽

Time Required

The rate of growth and chloramphenicol production of Streptomyces sp. 3022a can be controlled by varying the nitrogen source used in the medium. Sources such as peptone and nitrate support rapid growth but the high initial rate of antibiotic production was not sustained. Nitrogen sources which resulted in slow, controlled growth supported the highest yields of chloramphenicol. DL-Serine was the most suitable nitrogen source to use in this synthetic medium as good yields of chloramphenicol were obtained within a reasonable incubation period, e.g. 7 days.The substitution of part of the nitrogen supplied as DL-serine as nitrate (e.g. up to 2% of the total nitrogen supplied) decreased the fermentation time required without affecting the total amount of chloramphenicol produced. Nitrate at higher concentrations inhibited both chloramphenicol and mycelial production whereas the complete elimination of DL-serine from the medium restored mycelial production but not chloramphenicol production. Studies with 15N-nitrate showed that the nitro group of chloramphenicol does not originate from a biological nitration reaction but rather that both nitrogen atoms are derived from a common pool.The low dilution of radioactivity obtained from 14C-glycerol as compared with serine-1,3-14C indicates that serine does not have a special role as a precursor of chloramphenicol. Rather its value lies in its ability to control the growth rate of Streptomyces sp. 3022a, maintaining physiological conditions suitable for the formation of chloramphenicol.

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Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080407 ◽

1977 ◽

Vol 35 ◽

pp. 596-597

Author(s):

E. Keyhani

Keyword(s):

Plasma Membrane ◽

Candida Utilis ◽

Synthetic Medium ◽

Freeze Fracture ◽

Translational Diffusion ◽

Yeast Cells ◽

Distilled Water ◽

Intramembrane Particles ◽

The Matrix ◽

Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

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