The soil bacteria, CWBI-B1567 and CWBI-B1568, isolated from arid regions and identified as Bacillus subtilis (accession number KC341751) and Bacillus mojavensis (accession number KC341749) respectively, were screened and evaluated for their antifungal activity against Candida albicans, one of the most important human fungal pathogens. In vitro assay with the antagonists and their cell-free culture supernatants on agar plates showed that the two Bacillus strains effectively inhibited growth of the yeast. The capacity of these Bacillus strains to produce the cell-wall degrading enzymes was further studied. B. subtilis and B. mojavensis are able to produce cellulase and protease, but not chitinase. Bioactive molecules were produced by B. subtilis CWBI-B1567 and B. mojavensis CWBI-B1568 in a liquid culture medium optimised for lipopeptide production. The antifungal activity was equally demonstrated by testing the resulting supernatants and lipopeptide-enriched extracts. The electro-spray mass spectrometry coupled to liquid chromatography (ESI-LC-MS) analysis showed that both the B. subtilis and the B. mojavensis produced surfactin and iturin. However the fengycin group was produced only by B. mojavensis. Through this study, we have demonstrated that B. subtilis and B. mojavensis have a strong antifungal activity especially against C. albicans. This growth inhibition is probably due to the production of cell-wall degrading enzymes and different families of lipopeptide including iturins, fengycins and surfactins.

A total of 24 lipolytic yeasts were isolated from the spent olive derived from olive fruits of the Algerian variety Chemlal. One strain, G5, had the highest lipolytic activity (20 mm) on the tributyrin agar plate. The morphological, biochemical characterization and 18S rDNA gene analysis of the selected strain, confirms that it is Candida boidinii KF156789. The production of lipase and biomass were carried out in liquid and solid (spent olive) media. In submerged fermentation, it seemed that the production of enzyme reached its maximum 7.3 U/ml, whereas; the growth cells reached its maximum at 1.9 × 10 8 cell/ml. That can be explained by the assimilation of free fatty acids by this strain after degradation of olive oil by the enzyme. The production of lipase and biomass, in solid state fermentation, gave the maximum yield for cell growth (1.3 × 10 9 cell/ml), while lipolytic activity reached 4.8 U/g. The highest activity of the studied enzyme was at pH 7.0 and 37°C. The enzyme maintained more than 90% of its activity at pH 8.0-9.0 and 70% at temperature range of 4-40°C; it was concluded that the lipase from C. boidinii KF156789 has the potential to be an alkaline cold-adapted enzyme.