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  • Author: Tatiana Vassu x
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Fatty Acids Effect on Lipase and Biosurfactant Induction in Rhodotorula Glutinis CMGB-RG5

Abstract

Fatty acids represent important substrates for obtaining microbial lipases and biosurfactants. The yeast strain CMGBRG5 was identified as Rhodotorula glutinis using the BIOLOG MicroLog System. The opacity screening tests showed that R. glutinis CMGB-RG5 was able to produce lipases in presence of 1% Tween 80 after three days of incubation. Lipase induction was estimated as cell growth in presence of Tween 80, Tween 20, olive oil and tributyrin. After 48 hours, best results were obtained in presence of butyric acid, respectively, oleic acid: 2.2 × 107 cells/ml on tributyrin and 1.0 × 107 cells/ml on olive oil. Biosurfactant production was evaluated as emulsification index (E24%). After one week, high E24 values were obtained on fried sunflower oil (53%) and olive oil (35%). Crude and concentrated biosurfactants were tested against nine Candida strains. Best antimicrobial activity was observed for [20X] biosurfactants against C. tropicalis, C. guilliermondii and C. krusei. In conclusion, R. glutinis CGB-RG5 shows high potential for using fatty acids from various sources as unique carbon substrates for synthesis of biocompounds with high economic and biotechnological value.

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Antibiotic Susceptibility Profiles of Listeria monocytogenes Strains Isolated from Food Products and Clinical Samples

Abstract

Listeria monocytogenes has a ubiquitous distribution in nature and could contaminate food of animal origin, causing severe infections in humans. Till present, little is known about the antibiotic resistance profiles of these strains in Romania. The aim of this study was to determine the antibiotic susceptibility patterns of 37 L. monocytogenes strains isolated from animal derived foods and from clinical samples. Food samples were collected from meat and dairy products, between 2009 and 2013. Clinical samples were collected from patients with septicemia, meningitis/meningo-encephalitis, abortion cases and newborns, hospitalized during April 2010 - April 2013 in three medical institutions from Bucharest: Babes Hospital, Elias Hospital, National Institute of Infectious Diseases (INBI) Matei Bals. All tested isolates exhibited resistance to cephalosporins and nalidixic acid; one strain isolated from boiled shell snails was resistant to trimethoprim/sulfamethoxazole. The resistance to the first choice antibiotic ampicillin in L. monocytogenes strains isolated from severe infections is underlining the need of in vitro antibiotic susceptibility testing of each clinical isolate to establish the efficacy of different antibiotics, as well as of extended epidemiological studies to highlight the resistance profiles of L. monocytogenes strains circulating in our country.

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