Isolation and characterization of halophilic Archaea able to produce biosurfactants.

Halotolerant microorganisms able to live in saline environments offer a multitude of actual or potential applications in various fields of biotechnology. This is why some strains of Halobacteria from an Algerian culture collection were screened for biosurfactant production in a standard medium using the qualitative drop-collapse test and emulsification activity assay. Five of the Halobacteria strains reduced the growth medium surface tension below 40 mN m(-1), and two of them exhibited high emulsion-stabilizing capacity. Diesel oil-in-water emulsions were stabilized over a broad range of conditions, from pH 2 to 11, with up to 35% sodium chloride or up to 25% ethanol in the aqueous phase. Emulsions were stable to three cycles of freezing and thawing. The components of the biosurfactant were determined; it contained sugar, protein and lipid. The two Halobacteria strains with enhanced biosurfactant producers, designated strain A21 and strain D21, were selected to identify by phenotypic, biochemical characteristics and by partial 16S rRNA gene sequencing. The strains have Mg(2+), and salt growth requirements are always above 15% (w/v) salts with an optimal concentration of 15-25%. Analyses of partial 16S rRNA gene sequences of the two strains suggested that they were halophiles belonging to genera of the family Halobacteriaceae, Halovivax (strain A21) and Haloarcula (strain D21). To our knowledge, this is the first report of biosurfactant production at such a high salt concentration.

HP17, a new pigment-like antibiotic produced by a new strain of Spirillospora.

Spirillospora strain 719 produces several antibiotics. On solid and liquid media, a deep red pigments is formed and diffuses throughout the culture. It was extracted with methanol from the mycelium cake and from the fermentation broth after precipitation at pH 2 and purified using TLC and HPLC. Its u.v. absorption spectrum and its physicochemical characteristics place this antibiotic in the 3.3.2.2.8 of the Berdy et al. classification. In most respects, it resembles proteinaceous pigment from Spirillospora 1655 and 1309-b that was studied and named spirillomycin. However, HP17 differs from spirillomycin principally in molecular weight and chemical nature.

AH17, a new non-polyenic antifungal antibiotic produced by a strain of Spirillospora.

An antibiotic (AH17) was produced by Spirillospora strain 719. This substance was obtained only from the broth filtrate after precipitation with acetic acid followed by extraction with n-butanol. Its purification was carried out by thin layer chromatography on silica gel followed by HPLC procedures. It showed activity against Gram-positive and Gram-negative bacteria and fungi. The spectroscopic and chemical properties were examined and indicated that AH17 was a quinone. It seems that this is a new antibiotic from Spirillospora.

AH7, a non-polyenic antifungal antibiotic produced by a new strain of Streptosporangium roseum.

An antibiotic (AH7) produced by Streptosporangium roseum strain 214 was investigated. This compound was extracted with chloroform from the filtrate culture and purified using thin-layer chromatography and high pressure liquid chromatography procedures. The antibiotic strongly inhibited the growth of several strains of fungi and bacteria known to be plant and human pathogens. This compound differed from all other antibiotics known to be synthesized by Streptosporangium spp. Some of its chemical and physical properties resembled those of maytansines produced by Nocardia but the antibiotic AH7 has only antibacterial and antitumoral activities.

HM17, a new polyene antifungal antibiotic produced by a new strain of Spirillospora.

An antifungal antibiotic (HM17) was obtained from a new isolate classified to the genus Spirillospora on the basis of its chemical and morphological properties. On solid media this antibiotic strongly inhibited the growth of strains of Fusarium oxysporum formae speciales albedinis, Botrytis cinerea, Gaeumaniomyces graminis and several other fungi known to be plant and human pathogens. Antifungal activity in culture collection strains of Spirillospora has not so far been reported. The u.v. absorption spectrum and physico-chemical characteristics place HM17 in the methylpentaene sub-group of polyene macrolides. HM17 is different from other known methylpentaenes. This is the first report of polyene production by a Spirillospora.

Screening for non-polyenic antifungal antibiotics produced by rare Actinomycetales.

Strains of Actinomycetales (286 in toto) belonging to thirteen genera other than Streptomyces were isolated from different ecosystems in the Algerian Sahara. Among these strains, 32 showed antibiotic activity against at least one of the test organisms comprising four bacteria, two yeasts and several filamentous fungi, and twelve were antagonistic against both bacteria and fungi. The characteristic UV spectra of active extracts revealed that six strains produced non-polyenic antifungal substances and four synthetized polyenic substances. One strain of Spirillospora produced a pentaene antifungal substance. The only antibiotic so far known to be produced by this genus is spirillomycin.

H107, a new aminoglycoside anti-Pseudomonas antibiotic produced by a new strain of Spirillospora.

Spirillospora spp. (strain 719) has been the source of several antibiotics. One of these designated H107 is produced as a trace. Compared with other antibiotics produced by the same strain, it was obtained only from the broth filtrate after precipitation with acetic acid followed by extraction with n-butanol. It was a water soluble metabolite active against Gram-negative bacteria and especially Pseudomonas spp., and was identified as an aminoglycoside compound. This is the first report of aminoglycoside anti-Pseudomonas production by Spirillospora.