Cuevaenes A and B, new polyene carboxylic acids from Streptomyces sp. HKI 0180.
In the course of a screening for newmetabolites from strains of actinomycetes we disclosed Streptomyces sp. HKI 0180 as the producer of cuevaenes A (1) and B (2). The strain was isolated from a soil sample from the cave of Altamira (Spain). In this paper we report the production, isolation, structure elucidation and biological properties of 1 and 2 (Fig. 1). An agar slant culture of the above strain was used to inoculate a 500 ml Erlenmeyer flask containing 100ml of a seed medium composed of (g/liter): dextrose 15, soya bean meal 15, NaCl 5, CaCO3 1, KH2PO4 0.4, distilled water, pH 6.9. The producing medium contained (g/liter): mannitol 20, soya bean meal 20, distilled water, pH6.5.
Cuevaenes C–E: Three new triene carboxylic derivatives from Streptomyces sp. LZ35ΔgdmAI
Summary Two pairs of geometrical isomers – cuevaenes A (1) and C (3) as well as cuevaenes D (4) and E (5) – and cuevaene B (2) were isolated from gdmAI-disrupted Streptomyces sp. LZ35. The constitution of cuevaene C (3) was found to be identical to cuevaene A (1) by means of NMR spectroscopy and high resolution mass spectrometry. However, the relative configurations of the triene side chain moieties were determined to be different. It was established on the basis of spectroscopic data that cuevaenes D (4) and E (5) are amides and geometrical isomers. Cuevaenes A–C (1–3) displayed moderate activity against Gram-positive bacteria (e.g., Bacillus subtilis strain ATCC 11060) and modest activity against fungi (e.g., Fusarium verticillioides strain S68 and Rhizoctonia solani strain GXE4). However, cuevaenes D (4) and E (5) showed no inhibitory activity against any of the tested microbes.
Sustainable production of toxin free marine microalgae biomass as fish feed in large scale open system in the Qatari desert.
Mass cultivation of microalgae biomass for feed should be cost effective and toxin free. Evaporation loss in Qatar can be as high as 2 cm/d. Hence, production of marine microalgae biomass in Qatar would also require mitigating water loss as there was only very limited groundwater reserve. To address these issues, a combination of four growth conditions were applied to a 25,000 L raceway pond: locally isolated microalgae strain was selected which could grow in elevated salinity; strain that did not require silica and vitamins; volume of the culture would increase over time keeping denser inoculum in the beginning, and evaporation water loss would be balanced by adding seawater only. A local saline tolerant Nannochloropsis sp. was selected which did not require silica and vitamins. When the above conditions were combined in the pond, average areal biomass productivities reached 20.37 g/m(2)/d, and the culture was not contaminated by any toxic microalgae.