Effects of Fuzhuan Brick-Tea Water Extract on Mice Infected with E. coli O157:H7.

Fuzhuan brick-tea extract (FBTE) affects the physiology of mice infected with Escherichia coli O157:H7. For 10 consecutive days, 0.05, 0.5, and 1.0 g/mL FBTE was administered intragastrically to three groups of infected Kunming mice, and changes in immunological function, hematology, and histopathology were examined. The results revealed upregulation of platelets, total protein, and albumin along with downregulation of serum triglycerides, aspartate aminotransferase, creatinine, and urea nitrogen in FBTE-treated mice. Histological sections of stomach, kidney, duodenum, ileum, and colon suggested that infected mucous membranes could be rehabilitated by low- and high-dose FBTE and that inflammation was alleviated. Similarly, increased thymic function in mice treated with middle- and high-dose FBTE led to elevated serum hemolysin antibody titer and increased CD4+ and CD8+ T cells, as indicated by CD4+ and CD8+ expression on intestinal mucosa. Monocyte and macrophage function was improved by three FBTE dosages tested. Colonic microbiota analysis by denaturing gradient gel electrophoresis (DGGE) revealed characteristic bands in infected mice treated with middle- and high-dose FBTE and increased species diversity in Lactobacillus, Bacteroides, and Clostridium cluster IV. These results suggest that FBTE may protect kidney and liver of mice infected with E. coli O157:H7, improve immune function, and regulate the colonic microbiota.

Fungal community associated with fermentation and storage of Fuzhuan brick-tea.

Chinese Fuzhuan brick-tea is a unique microbial fermented tea characterized by a period of fungal growth during its manufacturing process. The aim of the present study was to characterize, both physicochemically and microbiologically, traditional industrial production processes of Fuzhuan brick-tea. Fermenting tea samples were collected from the largest manufacturer. Physicochemical analyses showed that the low water content in the tea substrates provided optimal growth conditions for xerophilic fungi. The fungal communities existing in tea materials, fermenting tea, and stored teas were monitored by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) targeting the D1 region of the 26S rRNA genes, followed by sequencing of the amplicons. Results revealed that the microorganisms were from, or closely related to, the genera Eurotium, Debaryomyces, Aspergillus, Verticillium, Pichia, Pestalotiopsis, Rhizomucor and Beauveria. This is the first report of Debaryomyces participating in the processing of Fuzhuan brick-tea. We concluded that the dominant genera Eurotium, Debaryomyces and Aspergillus are beneficial fungi associated with the fermentation of Fuzhuan brick-tea. The genus Beauveria was present in the stored Fuzhuan brick-tea, which may help protect tea products from insect spoilage. The remaining four genera were of minor importance in the manufacturing of Fuzhuan brick-tea. The predominant Eurotium species, a strain named Eurotium sp. FZ, was phenotypically and genotypically identified as Eurotium cristatum. High performance thin layer chromatography analysis of anthraquinones showed that emodin existed in all the dark tea samples, but physcion was only detectable in the tea fermented by E. cristatum. The PCR-DGGE approach was an effective and convenient means for profiling the fungal communities in Fuzhuan brick-tea. These results may help promote the use of microbial consortia as starter cultures to stabilize and improve the quality of Fuzhuan brick-tea products.