No abstract

The study investigated the impact of the fermentation process on the phenolic contents and antioxidant and anti-inflammatory activities in extracts of Miang, an ethnic fermented tea product of northern Thailand. The acetone (80%) extraction of Miang samples fermented by a non-filamentous fungi-based process (NFP) and filamentous fungi-based process (FFP) had elevated levels of total polyphenols, total tannins, and condensed tannins compared to young and mature tea leaves. The antioxidant studies also showed better the half-maximal inhibitory concentration (IC50) values for fermented leaves in both 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity assays as well as improved ferric reducing antioxidant power (FRAP) compared to young and mature tea leaves. Extracts of NFP and FFP samples at concentrations of 50 and 100 ppm showed better protective effects against hydrogen peroxide (H2O2)-induced intracellular reactive oxygen species (ROS) production in HT-29 colorectal cells without exerting cytotoxicity. Additionally, lipopolysaccharide (LPS)-induced production of nitric oxide (a proinflammatory mediator as well as a reactive nitrogen species) was also inhibited by these fermented Miang extracts with an IC50 values of 17.15 μg/mL (NFP), 20.17 μg/mL (FFP), 33.96 μg/mL (young tea leaves), and 31.33 μg/mL (mature tea leaves). Therefore, both NFP-Miang and FFP-Miang showed the potential to be targeted as natural bioactive functional ingredients with preventive properties against free radical and inflammatory-mediated diseases.

Our recent research study focused on Miang fermentation revealed that tannin-tolerant yeasts and bacteria play vital roles in the Miang production process. A high proportion of yeast species are associated with plants, insects, or both, and nectar is one of the unexplored sources of yeast biodiversity. Therefore, this study aimed to isolate and identify yeasts of tea flowers of Camellia sinensis var. assamica and to investigate their tannin tolerance, which is a property essential to Miang production processes. A total of 82 yeasts were recovered from a total of 53 flower samples in Northern Thailand. It was found that two and eight yeast strains were distinct from all other known species within the genera Metschnikowia and Wickerhamiella, respectively. These yeast strains were described as three new species, namely, Metschnikowia lannaensis, Wickerhamiella camelliae, and W. thailandensis. The identification of these species was based on phenotypic (morphological, biochemical, and physiological characteristics) and phylogenetic analyses of a combination of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) ribosomal RNA gene. The yeast diversity in tea flowers acquired from Chiang Mai, Lampang, and Nan provinces had a positive correlation with those acquired from Phayao, Chiang Rai, and Phrae, respectively. Wickerhamiella azyma, Candida leandrae, and W. thailandensis were the species uniquely found in tea flowers collected from Nan and Phrae, Chiang Mai, and Lampang provinces, respectively. Some of the tannin-tolerant and/or tannase-producing yeasts were associated with yeasts in the commercial Miang process and those found during Miang production, i.e., C. tropicalis, Hyphopichia burtonii, Meyerozyma caribbica, Pichia manshurica, C. orthopsilosis, Cyberlindnera fabianii, Hanseniaspora uvarum, and Wickerhamomyces anomalus. In conclusion, these studies suggest that floral nectar could support the formation of yeast communities that are beneficial for Miang production.

A total of 51 pentose utilizing lactic acid bacteria (LAB) were isolated from acid-forming bacteria in the midgut of healthy mature Eri silkworm using de Man, Rogosa and Sharpe (MRS) agar containing 10 g/L xylose (MRS-xylose) as the carbon source supplemented with 0.04% (w/v) bromocresol purple. Further analysis of 16S rRNA gene sequences revealed the highest prevalence of up to 35 enterococci isolates, which included 20 isolates of Enterococcus mundtii, followed by Entercoccus faecalis (eight isolates), Weissella cibaria (four isolates), Enterococcus hirae (two isolates), Enterococcus lactis (one isolate), and Enterococcus faecium (one isolate). All 51 LAB isolates showed positive growth on MRS containing a range of polysaccharides as the sole carbon source. All isolates were able to grow and form clear zones on MRS supplemented with 1 g/L xylose, while E. faecalis SC1, E. faecalis SCT2, and E. hirae SX2 showed tannin tolerance ability up to 5 g/L. Moreover, five isolates showed antimicrobial activity against Eri silkworm pathogens, including Bacillus cereus, Staphylococcus aureus, and Proteus vulgaris, with E. hirae SX2 having the highest inhibitory effect. Supplementation of live E. hirae SX2 on castor leaves significantly improved the weight and reduced the silkworm mortality when compared with the control group (p < 0.05). This cocci LAB can be considered as the new probiotic for Eri culture. Additionally, this finding presented the perspective of non-mulberry silkworm that could also be used as the model for further applying to new trends of the sericulture industry.

This research demonstrated an excellent potential approach for utilizing Miang fermentation broth (MF-broth), a liquid residual byproduct from the Miang fermentation process as a health-targeted beverage. One hundred and twenty yeast strains isolated from Miang samples were screened for their potential to ferment MF-broth and four isolates, P2, P3, P7 and P9 were selected, based on the characteristics of low alcoholic production, probiotic properties, and tannin tolerance. Based on a D1/D2 rDNA sequence analysis, P2 and P7 were identified to be Wikerhamomyces anomalus, while P3 and P9 were Cyberlindnera rhodanensis. Based on the production of unique volatile organic compounds (VOCs), W. anomalus P2 and C. rhodanensis P3 were selected for evaluation of MF-broth fermentation via the single culture fermentation (SF) and co-fermentation (CF) in combination with Saccharomyces cerevisiae TISTR 5088. All selected yeasts showed a capability for growth with 6 to 7 log CFU/mL and the average pH value range of 3.91–4.09. The ethanol content of the fermented MF-broth ranged between 11.56 ± 0.00 and 24.91 ± 0.01 g/L after 120 h fermentation, which is categorized as a low alcoholic beverage. Acetic, citric, glucuronic, lactic, succinic, oxalic and gallic acids slightly increased from initial levels in MF-broth, whereas the bioactive compounds and antioxidant activity were retained. The fermented MF-broth showed distinct VOCs profiles between the yeast groups. High titer of isoamyl alcohol was found in all treatments fermented with S. cerevisiae TISTR 5088 and W. anomalus P2. Meanwhile, C. rhodanensis P3 fermented products showed a higher quantity of ester groups, ethyl acetate and isoamyl acetate in both SF and CF. The results of this study confirmed the high possibilities of utilizing MF-broth residual byproduct in for development of health-targeted beverages using the selected non-Saccharomyces yeast.

Tea (Camellia sinensis var. assamica) is a traditional and economically important non-alcoholic beverage-producing plant grown in large plantations in the northern region of Thailand and has a diverse community of endophytic bacteria. In this study, a total of 70 bacterial isolates were isolated from healthy asymptomatic samples of tea leaves from five different tea gardens in Chiang Mai, Thailand. Based on 16S rDNA sequence analysis, these bacterial isolates were taxonomically grouped into 11 different genera, namely Bacillus, Curtobacterium, Enterobacter Microbacterium, Moraxella, Neobacillus, Priestia, Pseudarthrobacter, Pseudomonas, Sporosarcina, and Staphylococcus. All these isolates were evaluated for their potential to produce indole-3-acetic acid (IAA), siderophores, and cellulolytic enzymes while having phosphate-solubilizing and tannin tolerance capacity. Most isolated bacterial endophytes belonged to the Bacillus genus and exhibited multiple plant-growth-promoting abilities. All bacterial endophytes could produce varied concentrations of the indole-related compounds, and the strain Curtobacterium citreum P-5.19 had the highest production of IAA at 367.59 µg/mL, followed by Pseudarthrobacter enclensis P-3.12 at 266.97 µg/mL. Seventy-eight percent (78%) of the total isolates solubilized inorganic phosphate, while 77%, 65%, and 52% were positive for extracellular proteases, cellulases, and pectinases, respectively. Remarkably, 80% of the isolates were capable of growth on nutrient agar supplemented with 1% (w/v) tannic acid. C. citreum P-5.19 and P. enclensis P-3.12 were selected for evaluation of plant growth promotion, and it was found that both bacterial endophytes enhanced seed germination rate and improved seedling growth parameters such as fresh and/or dry weight, root length, and shoot lengths of sunflower and tomato seeds. The selected bacterial endophytes isolated from tea leaves in this study could be used in bioformulation for plant growth promotion and advancing sustainable agricultural practices contributing to the decreased use of chemical inputs. This is the first report of an endophytic bacterium, Pseudarthrobacter enclensis, being isolated from C. sinensis.

.) in Thailand Bussaban, B.; Kodchasee, P.; Apinyanuwat, S.; Kosawang, C.; Jonglaekha, N.