Changes in secoiridoids content and chemical characteristics of cultivated and wild Algerian olive oil, in term of fruit maturation

Wild varieties in nature are known to be better adapted to climate change and more resistant to arid conditions common in some regions of the world. Oil samples of two cultivated varieties, Chemlal and Lemli, and one sylvestris variety were collected at four different harvesting periods in the semi-arid region of Bouira, Algeria. The aim of this study was to determine the influence of the genetic and maturity factors on the quality indices (acidity, peroxides value, and the parameters K232, K270), fatty acids profile, phenolic composition, and antioxidant activity of monovarietal olive oils. The study showed that early harvest dates of the fruits produced oils richer in pigments and phenolic compounds, with high antioxidant activity registered in both wild and cultivated varieties. Moreover, all oil samples showed high values of secoiridoids exceeding 60–90% of total biophenols, with higher values found in oleaster oils, which are correlated with high resistance to oxidation attacks. UHPLC-DAD and UHPLC-HRMS analyses showed that the secoiridoids composition is dominated by a profile rich in several isomers of oleuropein and ligstroside aglycons, which in turn represent more than 60% of the total secoiridoids in olive and Oleaster oils. Furthermore, chemometric analysis on the data allowed a better appreciation of the sensitivity of the virgin olive oil composition to the changes in genetic and ripening factors. According to the principal component analysis, phenolic and fatty acid profiles were the most important components contributing to the discrimination between olive oil samples.

Insights into the draft genome sequence of bioactives-producing Bacillus thuringiensis DNG9 isolated from Algerian soil-oil slough

Bacillus thuringiensis is widely used as a bioinsecticide due to its ability to form parasporal crystals containing proteinaceous toxins. It is a member of the Bacillus cereus sensu lato, a group with low genetic diversity but produces several promising antimicrobial compounds. B. thuringiensis DNG9, isolated from an oil-contaminated slough in Algeria, has strong antibacterial, antifungal and biosurfactant properties. Here, we report the 6.06 Mbp draft genome sequence of B. thuringiensis DNG9. The genome encodes several gene inventories for the biosynthesis of bioactive compounds such as zwittermycin A, petrobactin, insecticidal toxins, polyhydroxyalkanoates and multiple bacteriocins. We expect the genome information of strain DNG9 will provide another model system to study pathogenicity against insect pests, plant diseases, and antimicrobial compound mining and comparative phylogenesis among the Bacillus cereus sensu lato group.