An actinomycete strain NM94 was isolated from a Saharan soil sample by a dilution agar plating method using chitin-vitamins B medium supplemented with penicillin. The strain presented the morphological and chemical characteristics of the genus Nonomuraea. On the basis of 16S rDNA analysis and physiological tests, this isolate was found to be quite different from the known species of Nonomuraea and might be new. The strain NM94 secreted several antibiotics on yeast extract malt extract glucose medium that were active against some Gram-positive bacteria, yeast, and fungi. The antibiotics were extracted with dichloromethane and detected by bioautography on silica gel plates using Mucor ramannianus and Bacillus subtilis as the test organisms. Among these antibiotics, a complex called 94A showed interesting antifungal activity. It was selected and purified by reverse-phase HPLC. This complex was composed of five compounds. Spectroscopic studies by infrared, mass, and (1)H NMR of the compounds were carried out. Initial results showed that these molecules differed from the known antibiotics produced by other Nonomuraea species.

Exopolysaccharides synthesized by lactic acid bacteria play a major role in the manufacturing of fermented dairy products as thickening agents. Exploration of the biodiversity of wild lactic acid bacteria from natural environments is currently the most suitable approach to search for the desired exopolysaccharide-phenotype. A total of 82 thermophilic lactic acid bacteria strains were isolated from Algerian raw camel milk. The isolation of strains was carried on modified Chalmers agar medium, under semi anaerobic conditions at 42°C. Bacterial isolates were phenotypically characterized and grouped into four genera: Lactobacillus (31.7%), Enterococcus (30.5%), Streptococcus (24.4%) and Pediococcus (13.4%). Based on the mucous type of the colonies, thirty EPS-positive strains were selected to be screened for their ability to produce exopolysaccharides. The production of polymers was carried out on Man, Rogosa and Sharpe (MRS) broth, supplemented with lactose and glucose as carbon sources. Yields quantification of soluble exopolysaccharides using a colorimetric method, showed that the selected strains produce yields ranging between 160 and 740 mg/l for Lactobacillus strains, between 126 and 319 mg/l for Streptococcus strains, between 70 and 242 mg/l for Enterococcus strains and between 132 and 134 mg/l for Pediococcus strains. This suggests that some strains have potential to be used as new culture starters for this and possibility other dairy products.

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Description du sujet. Cet article vise à caractériser la matière grasse de lait cru ovin collecté localement en milieu steppique algérien, très apprécié pour la production du smen (beurre traditionnel). Objectifs. L’objectif de cette étude consiste à étudier le profil en acides gras libres et en cholestérol ainsi que les indices lipidiques du lait cru ovin issu de deux races locales algériennes (Ouled-Djellal et Rumbi). Méthode. Le lait est collecté à un stade moyen de lactation auprès de 20 brebis de chaque race. La matière grasse est extraite selon la méthode Rose-Gotllieb. Les proportions en acides gras (AG) libres majeurs sont déterminées par chromatographie en phase gazeuse. Résultats. Les acides palmitique (24,4 % ± 3,3), oléique (24,2 % ± 4,6), stéarique (10,8 % ± 3,5), myristique (10,4 % ± 1,9) et caprique (8,3 % ± 3,5) représentent la majorité des acides gras présents en totalisant 78,1 % des AG totaux. Les proportions en AG saturés sont plus importantes que celles des AG insaturés (69,6 % ± 5,3 vs 30,8 % ± 5,1). Les AG monoinsaturés l’emportent sur les polyinsaturés (26,3 % ± 4,7 vs 4,5 % ± 1,1). Le lait de la race Ouled-Djellal est plus riche (p < 0,05) en AG à chaine courte que celui de la race Rumbi. Ce dernier est plus riche en AG à chaine moyenne, bien que la différence ne soit significative que pour les acides palmitique et palmitoléique (p < 0,05). Parmi les AG à chaine longue, seuls les acides stéarique (10,88 % ± 2,83 vs 12,34 % ± 2,75 ; p < 0,01) et arachidique (0,26 % ± 0,18 vs 0,35 % ± 0,09 ; p < 0,05) sont influencés par la race. Conclusions. Les résultats obtenus montrent une richesse plus élevée en AG du lait de la race Rumbi, comparativement à celui de la race Ouled-Djellal. Ce lait peut être valorisé en technologie pour fabriquer le beurre traditionnel et aussi générer une économie locale intéressante.

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