Sensible Functional Linear Discriminant Analysis Effectively Discriminates Enhanced Raman Spectra of Mycobacterium Species.

Tuberculosis caused by Mycobacterium tuberculosis complex (MTBC) is one of the major infectious diseases in the world. Identification of MTBC and differential diagnosis of nontuberculous mycobacteria (NTM) species impose challenges because of their taxonomic similarity. This study describes a differential diagnosis method using the surface-enhanced Raman scattering (SERS) measurement of molecules released by Mycobacterium species. Conventional principal component analysis and linear discriminant analysis methods successfully separated the acquired spectrum of MTBC from those of NTM species but failed to distinguish between the spectra of different NTM species. A novel sensible functional linear discriminant analysis (SLDA), projecting the averaged spectrum of a bacterial specie to the subspace orthogonal to the within-species random variation, thereby eliminating its influence in applying linear discriminant analysis, was employed to effectively discriminate not only MTBC but also species of NTM. The successful demonstration of this SERS-SLDA method opens up new opportunities for the rapid differentiation of Mycobacterium species.

Investigation of hygienic quality and freshness of marketed fresh seafood in Northern Taiwan.

To survey the hygienic quality and freshness of fresh fish and shellfish, 533 specimens of fish and shellfish were collected from fishing piers, traditional markets and supermarkets (including warehouses) in northern Taiwan during the winter (January-February) and summer (July-August) seasons for hygienic quality and freshness examinations. The indicators included total bacterial count, fecal coliform, Escherichia coli, volatile basic nitrogen (VBN) and K value judged from ATP-related compounds. It was found that the hygienic quality and freshness of fish and shellfish decreased in summer, especially for clam and mussel. The ratio of unacceptable hygienic quality or freshness of fish and shellfish was the highest in fecal coliform, followed by E. coli and others. The fecal coliform count in products from the traditional markets was the highest, followed by those from supermarkets and fishing piers. Secondary contamination seems to be the most important problem for hygienic quality and freshness of fish and shellfish.