Kin Sing Lam

The effects of space flight on the production of monorden by Humicola fuscoatra WC5157 in solid-state fermentation.

Abstract The effect of space flight on the production of the antibiotic monorden on two types of agar media, T8 and PG, by Humicola fuscoatra WC5157 was examined on board the US Space Shuttle mission STS-77 in May 1996. Paired space-flight and ground control samples were prepared using identical hardware, protocol, media, and inoculum. Inoculation occurred simultaneously for both groups 2.5 h after launch. The flight and ground samples were allowed to grow for the entire 10-day mission in a dark, thermally controlled (22 °C) environment. Post-flight HPLC analysis of the flight and ground sample extracts indicated that the production of monorden by H. fuscoatra WC5157 in the flight samples was higher than in the ground samples in both agar media. In the T8 medium, the production of monorden in the flight and ground samples was 11.6 ± 3.5 μg and 8.9 ± 1.1 μg respectively (30% increase). In the PG medium, the production of monorden in the flight and ground samples was 23.8 ± 3.3 μg and 8.2 ± 2.2 μg respectively (190% increase). The production of monorden in the flight and ground control samples was confirmed by HPLC-MS analysis.

The effect of space flight on the production of actinomycin D by Streptomyces plicatus

The effect of space flight on production of the antibiotic actinomycin D by Streptomyces plicatus WC56452 was examined onboard the US Space Shuttle mission STS-80. Paired space flight and ground control samples were similarly prepared using identical hardware, media, and inoculum. The cultures were grown in defined and complex media under dark, anaerobic, thermally controlled (20°C) conditions with samples fixed after 7 and 12 days in orbit, and viable residuals maintained through landing at 17 days, 15 h. Postflight analyses indicated that space flight had reduced the colony-forming unit (CFU) per milliliter count of S. plicatus and increased the specific productivity (pg CFU−1) of actinomycin D. The antibiotic compound itself was not affected, but its production time course was altered in space. Viable flight samples also maintained their sporulation ability when plated on agar medium postflight, while the residual ground controls did not sporulate.

Effect of neutral resins on the production of dynemicins by Micromonospora chersina

Addition of Diaion HP-20 or Amberlite XAD-8 resin to the fermentation ofMicromonospora chersina ATCC 53710 enhanced the production of dynemicin A by 4.7- and 6.9-fold, respectively. Addition of resin suppressed the production of other dynemicin analogs, which comprised 65% of the dynemicin complex in the fermentation.

Identification of indolepyruvic acid as an intermediate of rebeccamycin biosynthesis

SummaryExperimental evidence is presented to demonstrate that indolepyruvic acid is an intermediate in the rebeccamycin biosynthetic pathway. [3-14C]Indolepyruvic acid was prepared and efficiently incorporated (8%) into rebeccamycin bySaccharothrix aerocolonigenes.

The effect of cerulenin on the production of esperamicin A1 byActinomadura verrucosospora

SummaryAddition of cerulenin (0.25–1.0 mM) to cultures ofActinomadura verrucosospora before the onset of esperamicin synthesis inhibited the production of esperamicin A1 by the microorganism. This result indicates that esperamicin A1 is biosynthesized in part by the polyketide pathway. Addition of cerulenin to the cultures during the active production phase led to a net decrease in esperamicin A1 production. The14C-acetate labeling pattern of esperamicin A1 in the cultures with or without addition of cerulenin at the active production phase also demonstrated the instability of esperamicin A1 in the fermentation. This suggests that esperamicin A1 is unstable and degradation occurs during the active production phase. Addition of the neutral resin Diaion HP-20 (1%) to the fermentation enhanced the production of esperamicin A1 by 53%.

Carbon catabolite regulation of rebeccamycin production inSaccharothrix aerocolonigenes

SummaryA new antitumor antibiotic named rebeccamycin was isolated from fermentations of an actinomycete,Saccharothrix aerocolonigenes. A defined medium was developed to study the regulation of synthesis of rebeccamycin byS. aerocolonigenes. In glucose medium formation of rebeccamycin was detected only after glucose was depleted. Examination of eleven different carbon sources revealed that carbon catabolite regulation is a major control mechanism for rebeccamycin production.

Korkormicins, novel depsipeptide antitumor antibiotics fromMicromonospora sp C39500: Fermentation, precursor directed biosynthesis and biological activities

Micromonospora sp C39500, isolated in our laboratory from a soil sample, produced a complex of seven novel depsipeptide antitumor antibiotics, designated korkormicins. The major component of the complex, korkormicin A, has a MW of 1452 and a molecular formula of C66H84N16O22. Korkormicin A exhibits potentin vivo antitumor activity against P388 leukemia and M109 lung carcinoma implanted intraperitoneally (ip) in mice, with effective doses of 0.05–0.20 mg kg−1 injection−1, for five or three ip injections, respectively. It is also active against Gram-positive bacteria but inactive against Gram-negative bacteria. The production of korkormicin A was enhanced by 3-fold when 0.1%l-valine was added to the production culture at 48h. A titer of 401.0 μg ml−1 was achieved in the fermenter culture supplemented with 0.1%l-valine.

Improved processes for the production and isolation of dynemicin A and large-scale fermentation in a 10000-liter fermentor

SummarySupplementing the culture ofMicromonospora chersina sp. nov. No. M956-1 with NaI (0.5 mg/l) enhanced the production of dynemicin A by 35-fold in shake flask culture. Homogeneous dynemicin A was obtained from the whole broth extract by Dicalite chromatography, Sephadex LH-20 chromatography and vacuum liquid chromatography. Gram quantities of dynemicin A were obtained from the fermentation ofM. chersina sp. nov. No. M956-1 in a 10000-liter fermentor.

Enzymatic digestion of spent yeast cells for nutrient recycling in inulase production.

SummaryAn enzyme complex capable of lysing yeast cells was produced byArthrobacter sp. in a medium containing live cells ofKluyveromyces fragilis as the sole source of nutrients. The enzyme complex caused a 90% reduction in the optical density of viable yeast cells in 6 h at 25°C. This yeast cell hydrolysate can be used as a source of nitrogen, vitamins and minerals for subsequent growth of yeast cells (8.3 mg/ml) and further production of inulase (167 U/ml) representing 88 and 87% yield respectively, compared to cells grown on a standard yeast extract (1%) and sucrose (2%) medium.

N-Demethylation of nocathiacin I via photo-oxidation.

In order to improve aqueous solubility of nocathiacin I (1), a potent antibacterial agent, N-demethylation of the amino-sugar moiety was sought. Irradiation of 1 in DMF/CH(2)Cl(2) with UV light of 380 nm led to a cyclic product 2, which was hydrolyzed to yield the desired nocathiacin VI (3). Treatment of 1 with shorter UV light caused trans-cis isomerization of a c-c double bond.