Pu-erh tea is a popular beverage in Southeast Asia, especially in many areas of China. Natural fungal inoculation and fermentation form its special quality and function in health care. At the same time, a common assumption is that unknown fungi from natural inoculation may pose a risk for safety of drinking the beverage, leading to an urgent need for a thorough fungal survey of Pu-erh tea. The present paper reports the natural fungal colonizations isolated from 60 representative samples. The results of the survey showed that the fungal colonizations were isolated from all the samples studied, ranging from 1.6 ¥ 10 3 to 1.16 ¥ 10 5 cfu/g, and 62 isolates were identified to belong to 41 species of 19 genera, including 13 species of Aspergillus and seven species of Penicillium, and 21 species of other genera. The predominant fungi were yeasts and different species of the genus Aspergillus. The concrete species of the dominant fungi varied with environment conditions of various production places. Sample parameters such as water content, A W , pH, polyphenol content were recorded, though they appeared to have no obvious effects on the total number of fungi, whereas processing and storage methods evidently affected total number of fungi. Some species of fungi such as Aspergillus fumigatus, Penicillium spp., Trichoderma spp. and Fusarium culmorum, etc., which maybe excrete toxic metabolites, were isolated in the survey. Further evaluation on the safety of these fungi isolated from Pu-erh tea products is needed. PRACTICAL APPLICATIONSThis study investigated the fungal colonizatins exisiting in Pu-erh tea and some parameters concerning the storage of Pu-erh tea. These findings will help 3 Corresponding

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Ultra-high performance liquid chromatography-quadrupole-time of flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to study the diversity of tea polysaccharides and the dynamic changes in the physicochemical indexes of tea samples. FT-IR spectra and the free radical scavenging ability of tea polysaccharides, during pile-fermentation of post-fermented tea, were analyzed. The results showed that 23 saccharide components in tea polysaccharides were identified: these belonged to 11 monosaccharides, 5 oligosaccharides, and 6 derivatives of monosaccharides and oligosaccharides. The abundance of oligosaccharides decreased gradually, while monosaccharides, and derivatives of monosaccharides and oligosaccharides increased gradually with the development of pile-fermentation. According to the differences in polysaccharide composition and their abundance, the tea polysaccharide samples extracted from different pile-fermentation stages could be clearly classed into three groups, W-0, W-1~W-4 and W-5~C-1. The pile-fermentation process affected the yield, the content of each component, FT-IR spectra, and the DPPH free radical scavenging ability of tea polysaccharides. Correlation analysis showed that microorganisms were directly related to the changes in composition and the abundance of polysaccharides extracted from different pile-fermentation stages. The study will further help to reveal the function of tea polysaccharides and promote their practical application as a functional food.

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Contamination by ochratoxigenic fungi and its prevention during the pile-fermentation of post-fermented tea have always been a concern. The present study aimed to elucidate the anti-fungal effect and mechanism of polypeptides produced by B. brevis DTM05 (isolated from post-fermented tea) on ochratoxigenic fungi, and to to evaluate their use in the pile-fermentation process of post-fermented tea. The results showed that polypeptides (produced by B. brevis DTM05) with a strong antifungal effect against A. carbonarius H9 mainly had a molecular weight between 3 and 5 kDa. The Fourier-transform infrared spectra of this polypeptide extract showed that it was a mixture consisting mainly of polypeptides and small amounts of lipids and other carbohydrates. The polypeptide extracts significantly inhibited the growth of A. carbonarius H9, and its minimum inhibitory concentration (MIC) was 1.6 mg/L, which significantly reduced the survival rate of spores. The polypeptides also effectively controlled the occurrence and ochratoxin A (OTA) production of A. carbonarius H9 on the tea matrix. The lowest concentration of polypeptides that significantly inhibited the growth of A. carbonarius H9 on the tea matrix was 3.2 mg/L. The enhancement of the fluorescence staining signal in the mycelium and conidiospore showed that the polypeptides with a concentration of more than 1.6 mg/L increased the permeability of the mycelium membrane and conidial membrane of A. carbonarius H9. The significant increase in the extracellular conductivity of mycelia suggested the outward leakage of intracellular active substances, and also further indicated an increase in cell membrane permeability. Polypeptides with a concentration of 6.4 mg/L significantly down-regulated the expression level of the polyketide synthase gene related to OTA production (acpks) in A. carbonarius H9, which may be the fundamental reason why polypeptides affect OTA production. In conclusion, reasonable use of the polypeptides produced by B. brevis can destroy the structural integrity of the cell membrane, make the intracellular active substances leak outward, accelerate the death of fungal cells and down-regulate the expression level of the polyketide synthase gene in A. carbonarius; thus, they can effectively control the contamination of ochratoxigenic fungi and OTA production during the pile-fermentation of the post-fermented tea.