Yeasts Candida tropicalis, Yarrowia lipolytica, Wickerhamomyces anomalus, Issatchenkia orientalis, Kluyveromyces marxianus, Saprochaete suaveolens and Trichosporon coremiiforme were isolated and identified by physiological, biochemical tests with API 20C AUX system and molecular methods by restriction fragment analysis of PCR-amplified 28S-rRNA from Algerian fermented raw bovine milk (Rayeb). Selected yeasts S. suaveolens, I. orientalis, K. marxianus and W. anomalus produced esters and higher esters which can exert a pertinent influence on the sensory characteristics of Rayeb. Viability of S. suaveolens and W. anomalus using three methods of drying (freeze-drying, convective drying, and spray-drying) and during 4 months of storage at 4 °C and 25 °C in the darkness was studied. Immediately after each drying method, high survival was obtained using freeze-drying followed by convective drying in rice cakes and spray-drying respectively. During storage at 4 °C, convective drying provided better survival of yeast cultures of S. suaveolens and W. anomalus than freeze-drying. At 25 °C of storage, convective and freeze-dried yeast cultures showed no significant loss of viable cells up to 2 months of storage. Spray-dried yeast cultures had the greatest loss of viable count during the 3 months of storage at 25 °C.Keywords: Rayeb; yeasts; identification; volatile compounds; preservation methods.Practical Application: Conservation of selected yeasts that produce volatile compounds by convective air drying compared to high cost freeze-drying and spray-drying methods.
The biostimulation potentials of carrot peel waste and carob kibbles for bioremediation of crude petroleum-oil polluted soil were investigated. Temperature, pH, moisture, total petroleum hydrocarbon (TPH), and changes in microbial counts during 45 days were monitored when 4 mL of carrot peel waste or carob kibbles media were added to 200 g of crude oil polluted soil samples. Gas chromatography-flame ionization detection (GC-FID) was used to compare hydrocarbon present in the crude oil polluted soil and in pure fuel, composition of crude oil polluted soil was analyzed by X-ray diffraction (XRD), and the TPH was measured by distillation using distiller mud. The results showed that, at the end of experiments, the concentration of TPH decreased in crude oil polluted soil containing carrot peel waste with a percentage of 27 ± 1.90% followed by crude oil polluted soil containing carob kibbles (34 ± 1.80%) and in the unamended control soil (36 ± 1.27%), respectively. The log [Colony Forming Unit (CFU)/g] of total heterotrophic bacteria in the crude oil polluted soil increased from 10.46 ± 0.91 to 13.26 ± 0.84 for carrot peel waste, from 11.01 ± 0.56 to 11.99 ± 0.77 for carob kibbles and from 8.18 ± 0.39 to 8.84 ± 0.84 for control, respectively. Such results demonstrated that carrot peel could be used to enhance activities of the microbial hydrocarbon-degrading bacteria during bioremediation of crude petroleum-oil polluted soil.
The removal of oil-drilling mud contaminated soil generated from oilfields in the Algerian Sahara by bioaugmentation with Yarrowia lipolytica and biostimulation with carrot peel waste amendment during 45 days was investigated. Initially, the evaluation of growth and gasoil degrading ability of Yarrowia lipolytica in carrot peel waste, and carob kibbles media were compared. Afterwards, the effect of bioaugmentation and organic amendment on oil-drilling mud contaminated soil was studied for 45 days of study period. Total petroleum hydrocarbon (TPH) was measured by distillation using distiller mud. The results indicated that, higher augmentation in growth was observed in carrot peel waste medium and when the concentration of gasoil was increased from 15% to 30%. TPH decreased to 35 ± 1.66% and 30.60 ± 1.50% the first 15 days, 33 ± 2.30% and 26.8 ± 1.66%, respectively at the end of study. TPH rate did not undergo any significant change from its initial value in the control for the entire period of incubation. This study demonstrated the effectiveness of co-application of bioaugmentation with Yarrowia lipolytica and biostimulation with carrot peel waste amendment for bioremediation of oildrilling mud contaminated sites.
This work is part of the development and enhancement of natural substances and the search for effective, non-polluting and beneficial control methods for human health against insect pests of stored cereals. For this purpose, the essential oils extracted by hydro-distillation from two aromatic plants, i.e., Mentha spicata L. and Salvia officinalis L., were tested for their bio-insecticide effect against two different insect pest species affecting stored cereals: wheat weevil Sytophilusgranarius Linnaeus, 1758 (Coleoptera; Curculionidae (https://www.google.com/search?rlz=1C1RLNS_frDZ794DZ794&sxsrf=ALeKk02kJGWNyk9IHmU4edt2WofGTjHQjQ:1599765637919&q=Curculionidae&stick=H4sIAAAAAAAAAONgVuLUz9U3MDTNNs9ZxMrrXFqUXJqTmZ-XmZKYCgAlNltqHQAAAA&sa=X&ved=2ahUKEwjSqsm0p9_rAhVGxoUKHT7qDkEQmxMoATAkegQIDhAD)) and confused flour beetle Triboliumconfusum Jacquelin du Val, 1863 (Coleoptera; Tenebrionidae (https://en.wikipedia.org/wiki/Darkling_beetle)). A batch of adult insect individuals was introduced into each petri dish and placed in their respective oven. The test results showed that the aerial part of Sage and Spearmint have a toxic effect on adults of Weevil (60% mortality for Spearmint and 90% for Sage) and Tribolium (70% mortality for spearmint and 90% for sage). In conclusion, these two aromatic and medicinal plantsare naturally occurring substances that act as insecticides to control effectively the stored cereals insect pest species.
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