Traditional Chinese medicinal plants are sources of biologically active compounds, providing raw material for pharmaceutical, cosmetic and fragrance industries. The endophytes of medicinal plants participate in biochemical pathways and produce analogous or novel bioactive compounds. Panxi plateau in South-west Sichuan in China with its unique geographical and climatological characteristics is a habitat of a great variety of medicinal plants. In this study, 560 endophytic actinomycetes were isolated from 26 medicinal plant species in Panxi plateau. 60 isolates were selected for 16S rDNA-RFLP analysis and 14 representative strains were chosen for 16S rDNA sequencing. According to the phylogenetic analysis, seven isolates were Streptomyces sp., while the remainder belonged to genera Micromonospora, Oerskovia, Nonomuraea, Promicromonospora and Rhodococcus. Antimicrobial activity analysis combined with the results of amplifying genes coding for polyketide synthetase (PKS-I, PKS-II) and nonribosomal peptide synthetase (NRPS) showed that endophytic actinomycetes isolated from medicinal plants in Panxi plateau had broad-spectrum antimicrobial activity and potential natural product diversity, which further proved that endophytic actinomycetes are valuable reservoirs of novel bioactive compounds.

In this investigation, the effect of chitosan coating containing anti-browning agents and cinnamon oil fumigation on the microbiological and quality safety of fresh-cut pears was evaluated during 15 days of storage at 4C. The results showed that the combined application of chitosan coating and oil fumigation could retard the microbiological deterioration of fresh-cut pears. The L* value of samples treated by chitosan coating + oil fumigation was 61.15 at the end of storage. This combined treatment prevented product weight loss at the largest extent. Titratable acidity, vitamin C content and total phenolic content in treated slices presented the smallest changes throughout the storage time. Polyphenol oxidase activity of the sample treated by chitosan coating + oil fumigation was 26.90 U/g at the end of storage. These treated slices showed the lowest increase in malondialdehyde (MDA) content (2.9 mmol/g) and the highest overall visual quality values (5.6 scores) after 15 days of storage. These results indicated that the combined treatment of coating + oil fumigation could effectively maintain the microbiological and quality safety of fresh-cut pears. PRACTICAL APPLICATIONSThe growth of food-spoilage microorganisms and surface browning are the major causes of quality loss of fresh-cut pear during the storage time. Chitosan coating with anti-browning agents is useful for inhibiting the browning of tissue surface and keeping the nutrients in fresh-cut fruits. On the other hand, cinnamon oil inhibits the growth of bacteria and molds on sample slices. In this study, the combined application of chitosan coating and cinnamon oil fumigation could significantly control the browning and rot of fresh-cut pear. It could potentially be useful as a technology in maintaining the microbiological and quality safety of fresh-cut fruits. bs_bs_banner Journal of Food Safety

A novel halophilic actinomycete, designated strain YIM 93223 T , was isolated from a salt lake in Xinjiang Province, north-west China, and was subjected to a polyphasic taxonomic study. The isolate grew at 25-45 6C, at pH 6-8 and in the presence of 1-15 % (w/v) NaCl; no growth was observed in the absence of NaCl. Strain YIM 93223T contained meso-diaminopimelic acid, glutamic acid and alanine as cell-wall amino acids, and glucose and galactose as major whole-cell-wall sugars. Major fatty acids were iso-C 16 : 0 , C 16 : 0 and