147 research outputs found
Ruling Out Bacillus anthracis
Optimization of methods for ruling out Bacillus anthracis leads to increased yields, faster turnaround times, and a lighter workload. We used 72 environmental nonâB. anthracis bacilli to validate methods for ruling out B. anthracis. Most effective were horse blood agar, motility testing after a 2-h incubation in trypticase soy broth, and screening with a B. anthracisâselective agar
Lipase induction in Yarrowia lipolytica for castor oil hydrolysis and its effect on Îł-decalactone production
Îł-Decalactone is an aromatic compound of industrial interest, resulting from the biotransformation of ricinoleic acid, the major constituent of castor oil. In order to increase the availability of the substrate to the cells for the aroma production, castor oil previously hydrolyzed can be used. This hydrolysis may be promoted by enzymatic action, more specifically by lipases. In this work, the influence upon the aroma production of the lipase produced by Yarrowia lipolytica, a microorganism able to carry out the biotransformation, was studied. In a first approach, lipase induction conditions were analyzed using different Y. lipolytica strains and culture conditions, such as the inoculation mode of the lipase production medium. Lipase production was not affected by the cells centrifugation, so this step was eliminated, reducing the time and phases of the process. Moreover, Y. lipolytica W29 was shown to be the most adequate strain for lipase production. To investigate the importance of castor oil hydrolysis, the pre-addition of an inducer of lipase production (olive oil) to the biotransformation medium was tested. Results showed that the highest aroma production (1,600 mg Lâ1) was obtained without a lipase inducer. However, the pre-induction of lipase decreased the lag phase for Îł-decalactone secretion.The authors acknowledge Fundacao para a Ciencia e Tecnologia (FCT) for the financial support provided (SFRH/BD/28039/2006 and SFRH/BD/63701/2009). They also acknowledge the kind supply of Yarrowia lipolytica IMUFRJ 50862 by Professor Alice Coelho from UFRJ, Brazil, and the supply of Y. lipolytica W29 by Prof. Yves Wache, ENSBANA, Dijon, France
Adaptation of Brucella melitensis Antimicrobial Susceptibility Testing to the ISO 20776 Standard and Validation of the Method
This article belongs to the Special Issue Emerging Themes in Brucella and Brucellosis.Brucellosis, mainly caused by Brucella (B.) melitensis, is associated with a risk of chronification
and relapses. Antimicrobial susceptibility testing (AST) standards for B. melitensis are not
available, and the agent is not yet listed in the EUCAST breakpoint tables. CLSI recommendations
for B. melitensis exist, but they do not fulfill the requirements of the ISO 20776 standard regarding
the culture medium and the incubation conditions. Under the third EU Health Programme, laboratories
specializing in the diagnostics of highly pathogenic bacteria in their respective countries
formed a working group within a Joint Action aiming to develop a suitable method for the AST of B. melitensis. Under the supervision of EUCAST representatives, this working group adapted the
CLSI M45 document to the ISO 20776 standard after testing and validation. These adaptations included
the comparison of various culture media, culture conditions and AST methods. A Standard
Operation Procedure was derived and an interlaboratory validation was performed in order to evaluate
the method. The results showed pros and cons for both of the two methods but also indicate
that it is not necessary to abandon MuellerâHinton without additives for the AST of B. melitensis.This research was funded by the EU Health Programme 2014â2020, through the Consumers, Health, Agriculture and Food Executive Agency (CHAFEA, European Commission), the Joint
Action EMERGE (CHAFEA n° 677 066) and the Joint Action SHARP (848096-SHARP JA).info:eu-repo/semantics/publishedVersio
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