Differentiation of the genus Listeria is significant for food industry, but only few reliable methods are available so far. In the present study, 56 strains isolated from 345 samples of cow raw milk were used. The isolated pure cultures were defined by PCR-based method using specific primers of 16S-23S IGS region of DNA. Bacterial strain samples were submitted to spectroscopic measurements by the trans-mission method at a wavelength of 3000–700 cm–1 using Fourier-transform infrared (FTIR) spectro-photometry. Hierarchical cluster analysis (HCA) was performed based on the identification of the 56 isolated strains. The utilisation of HCA in univariate-FTIR spectral analyses as the most progressive chemometric method was supported by the correct identification of 86.9% bacteria of the genus Listeria at the species level. These results explained the ability of univariate-FTIR spectrum analysis for determination of suspected Listeria species.

Listeriosis is a serious, but preventable disease, and the virulence factor of this disease is produced only by the two pathogenic species L. monocytogenes and L. ivanovii in humans and/or animals. In this study, we used both denaturing gradient gel electrophoresis (DGGE) and constant denaturing gel electrophoresis (CDGE) as molecular methods combined with Polymerase Chain Reaction (PCR) for the detection and identification of Listeria pathogens on 543 samples of raw milk collected from all Syrian provinces. The two methods are based on the PCR amplification of a fragment of the InlC gene (virulence gene) from the studied Listeria species and on the analysis of the PCR products obtained by DGGE/CDGE. Based on the differences present in the sequences amplified, it was possible to obtain species-specific DGGE/CDGE migration that allowed fast and easy identification of the virulence and pathogenicity of L. monocytogenes and L. ivanovii in humans and/or animals, in order to reduce the incidence of Listeria bacteria in the environment and foods and to prevent the occurrence of listeriosis in animal and human hosts.

R E S U M O -C el ul a s e s s ã o e n z i m a s q u e c o n s t i t u e m um c om p l ex o c a p a z d e hidrolisar materiais celulósicos, liberando açúcares possíveis de serem convertidos em etanol durante a fermentação alcoólica. Neste trabalho, investigou-se a purificação e a utilização de complexo de celulase purificado pelo sistema de duas fases com polietilenoglicol (PEG) e citrato de sódio. O complexo enzimático bruto foi gerado por fermentação em estado sólido por Aspergillus niger e meio composto por farelo de arroz (60%) e bagaço de cana tratado com explosão a vapor (40%). Posteriormente, foi purificado com PEG de massa molar 2000-6000 g/mol. Os melhores resultados foram obtidos com o uso de PEG 2000 em concentração de 22% e pH 7,0, observando-se que a purificação não ocorre de forma homogênea para todas enzimas do complexo e revelando que, entre as enzimas -glicosidase, endoglucanase e exoglucanase, a endoglucanase apresentou maior fator de purificação (FP=2).