Richard Louis Pieper

The formation of daptomycin by supplying decanoic acid to Streptomyces roseosporus cultures producing the antibiotic complex A21978C

Antibiotic substance A21978C is a complex of compounds having a common cyclic polypeptide nucleus and different fatty acid sidechains. Daptomycin is a semi-synthetic antimicrobial substance derived from the A21978C complex by a very elaborate chemical process. To obtain the daptomycin, the A21978C complex was first isolated from culture filtrates of Streptomyces roseosporus by several resin procedures. The resulting material was then ‘blocked’ and added to an Actinoplanes culture for deacylation. The protected A21978C nucleus was subsequently isolated by the same procedure as the parent complex and reacylated with the desired fatty acid (decanoic acid). The acylated compound was deblocked to yield daptomycin. This report describes the experimentation undertaken to establish a strategy to supply a very toxic precursor to cultures of S. roseosporus and, thereby, produce daptomycin biosynthetically.

Sporulation ofStreptomyces roseosporus in submerged culture

SummaryA soil isolate ofStreptomyces roseosporus was found to produce spores in stirred submerged culture. Both biological mass and respiratory activity increased during the sporulation process. Contrary to other reports, the differentiation process was not purposefully initiated by critical manipulation of either nutritional or environmental conditions.

Interaction of media components during bioreactor sterilization: definition and importance of R0

SummarySterilization of bioreactor media, to destroy viability of the indigenous microbial population, is normally accomplished by autoclaving, or heating with pressurized steam. However, simultaneous chemical changes in media can also be expected to result from the high temperatures. A kinetic procedure involving on-line computer calculation of heat input, designated asF0 values, was previously developed to estimate sterility achievement. A similar kinetic procedure, based on a general purpose Arrhenius ‘pseudo’ rate equation and designated asR0 values, has now been designed to evaluate, and control the effects of temperature and heating time on chemical reactions occurring in the media. Data are presented indicating thatR0 may be a useful parameter for reducing variability in culture metabolism and ‘scale-up’ when these variations result from different nutrient concentrations produced by non-standard heating during media sterilization in stirred bioreactors.

The synthesis of A21978C analogs byStreptomyces roseosporus cultivated under carbon limitation and fed fatty acids

SummaryBy employing carbon limited fed batch techniques, fatty acids of length C8 to C12 were successfully employed as precursors for biosynthesis of A21978C antibiotics. The efficiency of incorporation was related to the length of the lipid precursor, with C10-C12 fatty acids being the preferred substrates.

Physiology of spore germination in cephalosporium acremonium

Conidia ofC. acremonium require an exogenous supply of carbon, nitrogen, magnesium, and phosphate for swelling and germ tube formation. Germination is stimulated by supplementing the medium with sulfate. Maximum frequency of germination occurs at a temperature of 27° to 32°C and a pH of 8.0. Conidia swell at pH 4.0 to 5.5 but do not form germ tubes. Conidia allowed to swell at pH 5.5 initiate germ tube formation immediately when the pH is adjusted to 7.5. Under optimal conditions, over 95 percent of the spore population formed germ tubes by 13 hours.

Characterization of the process for the biosynthesis of the actaplanin complex by Actinoplanes missouriensis

Abstract The production of the antibiotic actaplanin by Actinoplanes missouriensis was characterized in a high yielding process. The data generated, indicate that the antibiotic is synthesized during a period of declining cell mass as estimated by dry weight and viability. Further study demonstrated that the producing culture binds actaplanin and is inhibited by the antibiotic in the soluble form.