Microbiologique Microfilm™ EBEc - a Rapid Method for the Simultaneous Enumeration of Enterobacteriaceae and Escherichia coli.

BACKGROUND: The Enterobacteriaceae and generic Escherichia coli are routinely enumerated in foods as part of product release criteria, or in the case of swabs, for environmental monitoring. OBJECTIVE: Microbiologique Microfilm™ EBEc is intended to provide a rapid and easy-to-use method for simultaneous enumeration of Enterobacteriaceae and E. coli on foods and environmental surfaces. Methods: This study evaluated the performance of Microfilm™ EBEc against ISO methods (ISO 21528-2:2017 for Enterobacteriaceae and ISO 16649-2: 2001 for E. coli) in 20 food matrixes and two environmental surfaces. Inclusivity, exclusivity, lot-to-lot reproducibility, ruggedness and stability studies were also performed on Microfilm™ EBEc. RESULTS: No significant differences and high correlation coefficients (R2) were observed between the Microfilm™ EBEc and the corresponding ISO methods in spiked food matrixes and environmental samples. Inclusivity studies showed expected results for all the E. coli and Enterobacteriaceae strains tested. In terms of exclusivity testing, all the strains tested failed to grow on Microfilm™ EBEc. A lot-to-lot study showed no significant differences in mean difference (log10) counts among the three lots of the Microfilm™ EBEc. Ruggedness studies showed no significant differences in mean difference (log10) counts at varying incubation temperatures and times. Stability studies on the Microfilm™ EBEc showed that it is stable at 2-25°C for 12 months, and at 45°C for 6 weeks. CONCLUSIONS: The results of this study indicate that the Microfilm™ EBEc is equivalent to the corresponding ISO methods for enumeration of Enterobacteriaceae and E. coli. Highlights: Microfilm™ EBEc offers a convenient and relatively fast test method for simultaneous enumeration of Enterobacteriaceae and E. coli in 24 h and has an advantage over the corresponding ISO methods that require two assays on the same sample for enumeration of Enterobacteriaceae and E. coli Gram-negative indicator groups.

Performance Validation of the Microbiologique MicrofilmTM Test System for AOAC Research Institute Performance Tested MethodSMCertification.

The Microfilm™ Test System is intended for quantitative microbiology and consists of three types of Microfilms for aerobic plate count (Microfilm APC), total coliform and Escherichia coli count (Microfilm TCEc), and yeast and mold count (Microfilm YMC). This study evaluated the performance of the Microfilm Test System against International Organization for Standardization (ISO) methods on 20 food matrixes and 2 environmental surfaces. Ruggedness, robustness, and stability were also determined, while inclusivity and exclusivity studies were performed on Microfilm TCEc and YMC. An independent laboratory evaluated the performance on four food matrixes and one environmental surface. No significant differences and high correlation coefficients were observed between the Microfilm Test System and the corresponding ISO methods (ISO 4833-1:2013 for APC, ISO 4832:2006 for total coliform count, ISO 16649-2: 2001 for E. coli, and ISO 21527 Part 1 and Part 2 for YMC) in spiked food matrixes and environmental samples. These results were corroborated by the independent laboratory. Inclusivity and exclusivity studies for Microfilm TCEc showed expected results for all the E. coli strains tested (blue-violet or violet color), while the related coliforms showed the expected blue-green colonies on the Microfilm. Similarly, all 100 fungal strains tested showed typical growth on Microfilm YMC. Exclusivity testing on Microfilm TCEc and YMC showed no growth of nontarget organisms. Robustness and ruggedness studies showed no significant differences in mean difference counts at varying incubation temperatures and times. Stability studies on three lots of the Microfilm Test System showed that it is stable at 2-25°C for 12 months and at 45°C for 6 weeks.

Draft Genome Sequence of "Halomonas chromatireducens" Strain AGD 8-3, a Haloalkaliphilic Chromate- and Selenite-Reducing Gammaproteobacterium.

Here, we report the complete genome sequence (3.97 Mb) of "Halomonas chromatireducens" AGD 8-3, a denitrifying bacterium capable of chromate and selenite reduction under extreme haloalkaline conditions. This strain was isolated from soda solonchak soils of the Kulunda steppe, Russian Federation.

Methods coagulation/flocculation and flocculation with ballast agent for effective harvesting of microalgae.

The effects of coagulant (FeCl3·6H2O), various flocculants based on polyacrylamide (PAA), polyethylenoxide (PEO) and flocculated biomass as ballast agent, dosage and sedimental time on flocculation efficiency of harvesting Chlorella vulgaris GKV1 cultivated in a laboratory were investigated. The results of this work indicated that the flocculation efficiency achieved about 90% after 5 min of sedimentation when adding of coagulant and flocculant mixture (FeCl3 50 mg/l+PEO based Sibfloc-718 7.5 mg/l) or flocculant with ballast agent (Sibfloc-718 7.5 mg/l+10% flocculated biomass). PAA and PEO showed good flocculation efficiency at dosage of 0.025 and 0.015 g/l, respectively without pH adjustment. Finally, the most suitable flocculation method was discussed in this paper.