Regional characteristics of Lactobacillus plantarum group strains isolated from two kinds of Japanese post-fermented teas, Ishizuchi-kurocha and Awa-bancha

Changes in microbial diversity and volatile metabolites during the fermentation of Bulang pickled tea

The present study aimed to determine microbial community, short-chain fatty acids (SCFAs), and volatilome of Bulang pickled tea during fermentation. Sequencing of 16S rRNA and ITS revealed that Bualng pickled tea was dominated by Lactobacillus plantarum, unclassified Enterobacteriaceae, unclassified Debaryomyces, Candida metapsilosis, Cladosporium sphaerospermum, and unclassified Aspergillus. The overall contents of SCFAs increased, with acetic acid showing the highest content. A total of 398 differential volatile metabolites were detected using differential metabolomics analysis. Out of these different volatile compounds, ten key volatile compounds including (Z)-4-heptenal, 1-(2-thienyl)-ethanone, 5-methyl-(E)-2-hepten-4-one, 2-ethoxy-3-methylpyrazine, p-cresol, 2-methoxy-phenol, ethy-4-methylvalerate, 3-ethyl-phenol, p-menthene-8-thiol, and 2-s-butyl-3-methoxypyrazinewere were screened based on odor activity value (OAV). The Spearman correlation analysis showed a high correlation of SCFAs and volatile compounds with microorganisms, especially L. plantarum and C. sphaerospermum. This study provided a theoretical basis for elucidating the flavor quality formation mechanism of Bulang pickled tea.

Analysis of lactic acid bacteria species in Miang, a post-fermented tea in Thailand, and their potential use as probiotics

Introduction

Miang is one of the post-fermented teas made in Northern Thailand. Although lactic acid bacteria are involved in fermentation of Miang, details are still not clear. This study investigated the diversity of Lactobacillaceae bacteria, related to fermentation of Miang. Probiotic potential of isolated Lactobacillaceae bacteria was examined.

Methods

Lactobacillaceae bacteria were isolated from 52 Miang samples collected from three provinces in northern Thailand and identified by MALDI-TOF MS. Hemolytic activity, antibiotic susceptibility, antimicrobial activity and tolerance to gastrointestinal juice were examined for probiotic potential of isolates.

Results

A total of 1,181 Lactobacillaceae bacteria strains were isolated from Miang. The most abundant isolates were Lactiplantibacillus pentosus. Besides Lactiplantibacillus plantarum, Levilactobacillus brevis, Paucilactobacillus suebicus, Lacticaseibacillus pantheris, and Secundilactobacillus collinoides were also found with frequency. Of these isolates, 450 with a high score for MALDI-TOF identification were then screened for probiotic ability. Most isolates were resistant to aminoglycosides and clindamycin. Then, 35 isolates were tested for their antimicrobial activity against pathogens using the well diffusion method, and 31 isolates exhibited inhibition zones against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella enterica serovar Typhimurium, S. enterica serovar Enteritidis, Listeria monocytogenes, Propionibacterium acnes, and Streptococcus mutans. All 31 isolates were non-hemolytic and readily tolerated simulated gastric juice at pH 3 and simulated intestinal juice at pH 8.

Discussion

Miang contains lactic acid bacteria that could potentially be used as probiotics.

Genome Sequencing Unveils Nomadic Traits of Lactiplantibacillus plantarum in Japanese Post-Fermented Tea

Post-fermented tea production involving microbial fermentation is limited to a few regions, such as Southeast Asia and Japan, with Japan's Shikoku island being particularly prominent. Lactiplantibacillus plantarum was the dominant species found in tea leaves after anaerobic fermentation of Awa-bancha in Miyoshi City, Tokushima, and Ishizuchi-kurocha in Ehime. Although the draft genome of L. plantarum from Japanese post-fermented tea has been previously reported, its genetic diversity requires further exploration. In this study, whole-genome sequencing was conducted on four L. plantarum strains isolated from Japanese post-fermented tea using nanopore sequencing. These isolates were then compared with other sources to examine their genetic diversity revealing that L. plantarum isolated from Japanese post-fermented tea contained several highly variable gene regions associated with sugar metabolism and transportation. However, no source-specific genes or clusters were identified within accessory or core gene regions. This study indicates that L. plantarum possesses high genetic diversity and that the unique environment of Japanese post-fermented tea does not appear to exert selective pressure on L. plantarum growth.

Analysis of D-amino acid in Japanese post-fermented tea, Ishizuchi-kurocha

The D-amino acid content of Ishizuchi-kurocha, a post-fermented tea produced in Ehime, Japan, was measured. Ishizuchi-kurocha mainly contains D-glutamic acid and D-alanine, but it also contains a small amount of D-aspartic acid. Two types of lactic acid bacteria, Lactiplantibacillus plantarum and Levilactobacillus brevis, are the main species involved in lactic acid fermentation during the tea fermentation process. Therefore, the D-amino acid-producing abilities of strains of these two species isolated from Ishizuchi-kurocha were examined. Specifically, the production of D-aspartic acid, D-alanine, and D-glutamic acid by L. brevis and L. plantarum strains was observed. The amount of D-aspartic acid produced by L. plantarum was low. D-glutamine was detected in culture supernatant but not in bacterial cells. D-arginine was detected in bacterial cells of the L. plantarum strains but not in the culture supernatant. Both the L. brevis and L. plantarum strains possessed at least three kinds of putative racemase genes: alanine racemase, glutamate racemase, and aspartate racemase. However, their expression and enzyme activity remain unknown. L. plantarum and L. brevis could play an important role in the production of D-amino acids in Ishizuchi-kurocha. In fact, Ishizuchi-kurocha is expected to possess the effective physiological activities of D-amino acids.

Dynamic Analysis of the Bacterial Community and Determination of Antioxidant Capacity during the Fermentation of Sour Tea

The imbalance of the redox state caused by extra reactive oxygen species is closely related to many diseases. Therefore, it is necessary for people to ingest antioxidants through food. The safety of some synthetic antioxidants has been questioned. In this context, it is worth exploring natural and safe antioxidants from biological sources. Tea has good antioxidant activity, and the antioxidant activity of fermented sour tea is better than that of other types. It is necessary to clarify the antioxidant capacity of sour tea during fermentation, as well as the microbial community and its sources. Nonculture and culture-dependent methods were adopted to track the changes in the microbial population and community structure during the fermentation of sour tea. Sequence analysis of 16S rRNA gene amplification revealed significant differences in community complexity and structure at different fermentation times. The highest proportion of operational taxonomic units (OTU s) in all samples was Latilactobacillus, which was determined to be Lactiplantibacillus plantarum by further analysis. The second highest proportion of OTUs was Enterobacter. With the fermentation of sour tea, the antioxidant capacity increased, and all isolated Lb. plantarum had good DPPH clearance rates. Our findings suggest that Lb. plantarum plays a crucial role in the fermentation process of sour tea. The possibility of discovering new antioxidants was provided by the determination of the antioxidant capacity and bacterial community during the fermentation of sour tea.

Lactiplantibacillus plantarum LOC1 Isolated from Fresh Tea Leaves Modulates Macrophage Response to TLR4 Activation

Previously, we demonstrated that Lactiplantibacillus plantarum LOC1, originally isolated from fresh tea leaves, was able to improve epithelial barrier integrity in in vitro models, suggesting that this strain is an interesting probiotic candidate. In this work, we aimed to continue characterizing the potential probiotic properties of the LOC1 strain, focusing on its immunomodulatory properties in the context of innate immunity triggered by Toll-like receptor 4 (TLR4) activation. These studies were complemented by comparative and functional genomics analysis to characterize the bacterial genes involved in the immunomodulatory capacity. We carried out a transcriptomic study to evaluate the effect of L. plantarum LOC1 on the response of murine macrophages (RAW264.7 cells) to the activation of TLR4. We demonstrated that L. plantarum LOC1 exerts a modulatory effect on lipopolysaccharide (LPS)-induced inflammation, resulting in a differential regulation of immune factor expression in macrophages. The LOC1 strain markedly reduced the LPS-induced expression of some inflammatory cytokines (IL-1β, IL-12, and CSF2) and chemokines (CCL17, CCL28, CXCL3, CXCL13, CXCL1, and CX3CL1), while it significantly increased the expression of other cytokines (TNF-α, IL-6, IL-18, IFN-β, IFN-γ, and CSF3), chemokines (IL-15 and CXCL9), and activation markers (H2-k1, H2-M3, CD80, and CD86) in RAW macrophages. Our results show that L. plantarum LOC1 would enhance the intrinsic functions of macrophages, promoting their protective effects mediated by the stimulation of the Th1 response without affecting the regulatory mechanisms that help control inflammation. In addition, we sequenced the LOC1 genome and performed a genomic characterization. Genomic comparative analysis with the well-known immunomodulatory strains WCSF1 and CRL1506 demonstrated that L. plantarum LOC1 possess a set of adhesion factors and genes involved in the biosynthesis of teichoic acids and lipoproteins that could be involved in its immunomodulatory capacity. The results of this work can contribute to the development of immune-related functional foods containing L. plantarum LOC1.

Controlling the microbial composition during the fermentation of Ishizuchi-kurocha

Ishizuchi-kurocha is a popular postfermented tea in Japan. It is performed by domestic and natural fermentation relied on microorganisms derived from tea leaves or the environment of the manufacturing. Ishizuchi-kurocha undergoes aerobic fermentation of fungi first, then second fermented by anaerobic fermentation of lactic acid bacteria during natural fermentation processing. Aspergillus niger that produces mycotoxin is included in natural fermentation. This research aimed to build a novel fermentation method of Ishizuchi-kurocha by adding industrial koji fungi products and laboratory-cultivated Lactobacillus plantarum (Lactiplantibacillus plantarum) artificially. Thus, safety and quality of tea products could be controlled simply. We found artificial fermentation of Ishizuchi-kurocha could get high lactic acid production within 8 days. Final products only consisted of genus Aspergillus and genus Lactobacillus, while harmful Aspergillus niger was not found. However, artificial fermentation methods also decreased the content of polyphenols when compared with commercial tea.

Isolation, identification, and impact on intestinal barrier integrity of Lactiplantibacillus plantarum from fresh tea leaves (Camellia sinensis)

Lactic acid bacteria (LAB) are safe microorganisms that have been used in the processing of fermented food for centuries. The aim of this study was to isolate Lactobacillus from fresh tea leaves and examine the impact of an isolated strain on intestinal barrier integrity. First, the presence of Lactobacillus strains was investigated in fresh tea leaves from Kagoshima, Japan. Strains were isolated by growing on De Man, Rogosa and Sharpe (MRS) agar medium containing sodium carbonate, followed by the identification of one strain by polymerase chain reaction (PCR) and pheS sequence analysis, with the strain identified as Lactiplantibacillus plantarum and named L. plantarum LOC1. Second, the impact of strain LOC1 in its heat-inactivated form on intestinal barrier integrity was investigated. Strain LOC1, but not L. plantarum ATCC 14917^T or L. plantarum ATCC 8014, significantly suppressed dextran sulfate sodium (DSS)-induced decreases in transepithelial electrical resistance values of Caco-2:HT29-MTX 100:0 and 90:10 co-cultures. Moreover, in Caco-2:HT29-MTX co-cultures (90:10 and 75:25), levels of occludin mRNA were significantly increased by strain LOC1 compared with untreated co-cultures, and strain LOC1 had higher mRNA levels of MUC2 and MUC4 mucins than L. plantarum ATCC 14917^T and L. plantarum YT9. These results indicate that L. plantarum LOC1 may be used as a safe probiotic with beneficial effects on the intestinal barrier, suggesting that fresh tea leaves could be utilized as a safe source for isolating probiotics.

Eurotium Cristatum Postfermentation of Fireweed and Apple Tree Leaf Herbal Teas

Fungi Eurotium spp. are the main biological agents that ferment the leaves of the Camellia sinensis tea bush to form a popular food product, postfermented tea. The fungus E. cristatum, stored in the collection of the Gause Institute of New Antibiotics under the number INA 01267, was isolated and identified from a briquette of Fujian Chinese tea. The species identification was carried out based on morphocultural characteristics and DNA sequencing. This study is aimed at determining the feasibility of making postfermented herbal teas using E. cristatum and to evaluate their quality. Autofermented herbal teas from Chamaenerion angustifolium (fireweed) and Malus domestica (apple tree) served as the starting material for this study. The change in the concentration of phenolic compounds, organic acids, sugars, and free amino acids was observed for herbal teas subjected to postfermentation with E. cristatum INA 01267. It was found that the E. cristatum INA 01267 strain does not have antimicrobial activity and does not form mycotoxins, which is an indicator of food safety.

Draft Genome Sequence of Lactiplantibacillus pentosus AWA1501, Isolated from Awa-bancha

Lactiplantibacillus pentosus AWA1501 was isolated from the traditional Japanese tea Awa-bancha. Previous studies have reported that this species becomes predominant after the anaerobic fermentation process. In this study, we report the whole-genome sequence of this strain. The draft genome sequence comprises 3,714,221 nucleotides and 3,374 coding DNA sequences, with an average G+C content of 46.02%.

Draft Genome Sequence of Lactobacillus plantarum IYO1511, Isolated from Ishizuchi-Kurocha

Lactobacillus plantarum IYO1511, isolated from a traditional postfermented tea, is a predominant species associated with Ishizuchi-kurocha. Here, we report the whole-genome sequence of this bacterium. The draft genome comprises 3,229,083 nucleotides and 3,044 coding DNA sequences (CDSs), with an average G+C content of 44.5%.

Lactobacillus plantarum IYO1511, isolated from a traditional postfermented tea, is a predominant species associated with Ishizuchi-kurocha. Here, we report the whole-genome sequence of this bacterium. The draft genome comprises 3,229,083 nucleotides and 3,044 coding DNA sequences (CDSs), with an average G+C content of 44.5%.

Culture-based analysis of fungi in leaves after the primary and secondary fermentation processes during Ishizuchi-kurocha production and lactate assimilation of P. kudriavzevii

Ishizuchi-kurocha is a Japanese traditional fermented tea that is produced by primary aerobic and secondary fermentation steps. The secondary fermentation step of Ishizuchi-kurocha is mainly mediated through lactic acid bacteria. Here, we performed quantitative analyses of the culturable fungal communities at each step and identified several morphologically representative fungal isolates. While filamentous fungi (median, 3.2 × 10⁷ CFU/g sample) and yeasts (median, 3.7 × 10⁷ CFU/g) were both detected after the primary fermentation step, only yeasts (median, 1.6 × 10⁷ CFU/g) were detected in the end of the secondary fermentation step, suggesting that the fungal community in tea leaves are dramatically changed between the two steps. Pichia kudriavzevii and Pichia manshurica, the prevalent fungal species at the end of the secondary fermentation step, grew well in exudate from the secondary fermentation step. P. kudriavzevii also grew well in media containing d- or l-lactate as the sole carbon source. The growth of the disruptant of cyb2A encoding a cytochrome b₂ lactate dehydrogenase in P. kudriavzevii was severely impaired on medium supplemented with l-lactate, but not d-lactate, suggesting that Cyb2Ap plays a crucial role in the use of l-lactate, and P. kudriavzevii efficiently uses both l- and d-lactate as carbon sources. Thus, lactate assimilation seems to be a key phenotype to become a prevalent species in the secondary fermentation step, and Cyb2Ap has a pivotal role in l-lactate metabolism in P. kudriavzevii. Further understanding and engineering of P. kudriavzevii and P. manshurica will contribute to the control of lactic acid bacteria fermentation during the fermented tea production and also to other industrial uses.