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    Biosurfactant production from newly isolated Rhodotorula sp.YBR and its great potential in enhanced removal of hydrocarbons from contaminated soils
    (Springer, 2021) Derguine-Mecheri, Louiza; Kebbouche-Gana, Salima; Djenane, Djamel
    One of the very promising methods in the field of bioremediation of hydrocarbons is the application of biosurfactant- producing microorganisms based on the use of wastewater as renewable substrates of culture media, contributing to the reduction of costs. With this aim, the production, characterization and properties of the yeast strain YBR producing a biosurfactant newly isolated from an oilfield in Algeria, using wastewater from olive oil mills (OOMW) as a substrate for a low-cost and effective production, have been investigated. Screening of biosurfactant production was carried out with different tests, including emulsification index test (E24), drop collapse test, oil spreading technique and measurement of surface tension (ST). The isolated yeast strain was found to be a potent biosurfactant producer with E24 = 69% and a significant reduction in ST from 72 to 35 mN m-1. The study of the cultural, biochemical, physiological and genetic characteristics of the isolate allowed us to identify it as Rhodotorula sp. strain YBR. Fermentation was carried out in a 2.5 L Minifors Bioreactor using crude OOMW as culture medium, the E24 value reached 90% and a reduction of 72 to 35 mN m-1 in ST. A biosurfactant yield = 10.08 ± 0.38 g L-1 was recorded. The characterization by semi-purification and thin layer chromatography (TLC) of the crude extract of biosurfactant showed the presence of peptides, carbohydrates and lipids in its structure. The crude biosurfactant exhibited interesting properties such as: low critical micellar concentration (CMC), significant reduction in ST and strong emulsifying activity. In addition, it has shown stability over a wide range of pH (2-12), temperature (4-100 °C) and salinity (1-10%). More interestingly, the produced biosurfactant has proven to be of great potential application in the remobilization of hydrocarbons from polluted soil with a removal rate of greater than 95%
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    Microbacterium algeriense sp. nov., a novel actinobacterium isolated from Algerian oil production waters
    (Microbiology Society, 2020) Lenchi, Nesrine; Anzil, Adriana; Servais, Pierre; Kebbouche-Gana, Salima; Gana, Mohamed Lamine
    A non-motile, straight-rod-shaped, Gram-stain-positive and facultative anaerobic bacterium (i.e., strain G1T) was isolated from production waters from an Algerian oilfield. Growth was observed in the presence of 0.3-3.5 % (w/v) NaCl, at 20-50 °C and at pH 6.0-9.0. Results of phylogenetic analyses based on 16S rRNA gene sequences showed that strain G1T belonged to the genus Microbacterium. Strain G1 T was closely related to Microbacterium oxydans (DSM 20578T) and Microbacterium maritypicum (DSM 12512T) with 99.8 % sequence similarity and to Microbacterium saperdae (DSM 20169T) with 99.6 % sequence similarity. Strain G1 T contained MK9, MK10, MK11, MK12 and MK13 as respiratory quinones, and phosphatidylglycerol, diphosphatidylglycerol and glycolipid as the major polar lipids. The major cellular fatty acids were anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The estimated DNA G+C content was 69.57 mol% based on its draft genome sequence. Genome annotation of strain G1T predicted the presence of 3511 genes, of which 3483 were protein-coding and 47 were tRNA genes. The DNA-DNA hybridization (DDH) and average nucleotide identity (ANI) values between strain G1T and M. oxydans (DSM 20578T) and M. maritypicum (DSM 12512T) were in both cases far below the respective species boundary thresholds (27.5 and 28.0 % for DDH; and 84.40 and 84.82% for ANI, respectively). Based on the data presented above, strain G1T was considered to represent a novel species for which the name Microbacterium algeriense is proposed with the type strain G1T (=DSM 109018T=LMG 31276T)