Simultaneous Production of Multiple Antimicrobial Compounds by Bacillus velezensis ML122-2 Isolated From Assam Tea Leaf [Camellia sinensis var. assamica (J.W.Mast.) Kitam.]

Bacillus velezensis ML122-2 is an antimicrobial-producing strain isolated from the leaf of Assam tea or Miang [Camellia sinensis var. assamica (J.W.Mast.) Kitam.]. The cell-free supernatant (CFS) of strain ML122-2 exhibits a broad-spectrum antimicrobial activity against various Gram-positive and Gram-negative bacteria as well as the mold Penicillium expansum. The genome of B. velezensis ML122-2 was sequenced and in silico analysis identified three potential bacteriocin-associated gene clusters, that is, those involved in the production of mersacidin, amylocyclicin, and LCI. Furthermore, six gene clusters exhibiting homology (75–100% DNA sequence identity) to those associated with the secondary metabolites bacilysin, bacillibactin, surfactin, macrolactin H, bacillaene, and plipastatin were identified. Individual antimicrobial activities produced by B. velezensis ML122-2 were purified and characterized by Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry analysis, revealing three antimicrobial peptides with molecular masses corresponding to surfactin, plipastatin, and amylocyclicin. Transcriptional analysis of specific genes associated with mersacidin (mrsA), amylocyclicin (acnA), plipastatin (ppsA), and surfactin (srfAA) production by B. velezensis ML122-2 showed that the first was not transcribed under the conditions tested, while the latter three were consistent with the presence of the associated peptides as determined by mass spectrometry analysis. These findings demonstrate that B. velezensis ML122-2 has the genetic capacity to produce a wide range of antimicrobial activities that may support a specific community structure and highlight the biotechnological properties of Assam tea.

An Updated Global Species Diversity and Phylogeny in the Genus Wickerhamomyces with Addition of Two New Species from Thailand

Ascomycetous yeast species in the genus Wickerhamomyces (Saccharomycetales, Wickerhamomycetaceae) are isolated from various habitats and distributed throughout the world. Prior to this study, 35 species had been validly published and accepted into this genus. Beneficially, Wickerhamomyces species have been used in a number of biotechnologically applications of environment, food, beverage industries, biofuel, medicine and agriculture. However, in some studies, Wickerhamomyces species have been identified as an opportunistic human pathogen. Through an overview of diversity, taxonomy and recently published literature, we have updated a brief review of Wickerhamomyces. Moreover, two new Wickerhamomyces species were isolated from the soil samples of Assam tea (Camellia sinensis var. assamica) that were collected from plantations in northern Thailand. Herein, we have identified these species as W. lannaensis and W. nanensis. The identification of these species was based on phenotypic (morphological, biochemical and physiological characteristics) and molecular analyses. Phylogenetic analyses of a combination of the internal transcribed spacer (ITS) region and the D1/D2 domains of the large subunit (LSU) of ribosomal DNA genes support that W. lannaensis and W. nanensis are distinct from other species within the genus Wickerhamomyces. A full description, illustrations and a phylogenetic tree showing the position of both new species have been provided. Accordingly, a new combination species, W. myanmarensis has been proposed based on the phylogenetic results. A new key for species identification is provided.

Locating 'Coolie' Women's Health in Tea Plantation Environments in Colonial Assam

The history of Assam tea plantations in India is well-documented, yet a gender sensitive environmental history of these colonially-introduced plantation landscapes is absent. The colonial tea planters saw advantages in a growing female presence in their plantations, in terms of increased male ties to the plantation, lower wages for female workers and the added benefit of biological reproduction that would fulfil the need for manual labour in these plantations for generations. This paper attempts to understand how this plantation structure in general and the work regime in particular relied on a particular type of gender identity, which in turn had a detrimental effect on the health of the women labourers in this new landscape.

Volatile profiles and antioxidant activity of different cultivars of Camellia sinensis var. assamica grown in Thailand

Tea is considered as the most consumed drink in the world containing high antioxidant capacity. In this study, the volatile compounds, the phenolic content, catechins and caffeine including antioxidant activities of 22 Camellia sinensis var. assamica (Assam tea) cultivars were investigated. The volatile compounds were investigated by GC-MS. At least forty-five volatile compounds representing 94.99-99.65% of all cultivars were identified. Limonene, trans-linalool oxide, cis-linalool oxide, linalool, and furfural were detected as the major components among these cultivars. Varied ranges were found in all Assam tea cultivars for the contents of phenolics (113.45-245.55 mg gallic acid/g dry weight), total catechins (170.03-355.59 mg/g dry weight), caffeine (0.92-3.40 mg/g dry weight), and antioxidant activities (1418.68-2728.46 µmol Trolox/g dry weight and 1448.98-2864.17 µmol Trolox/g dry weight for DPPH and ABTS assay, respectively). The antioxidant activity was correlated with phenolic compounds such as epigallocatechin gallate, epicatechin gallate, and catechin gallate. The specific differences among Assam tea cultivars are dependent on the tea cultivar and altitude which may play a significant role in breeding Assam tea cultivars in Thailand for providing its potential health benefits.

Culturable Bacterial Community on Leaves of Assam Tea (Camellia sinensis var. assamica) in Thailand and Human Probiotic Potential of Isolated Bacillus spp.

Assam tea plants (Camellia sinensis var. assamica) or Miang are found in plantations and forests of Northern Thailand. Leaf fermentation has been performed for centuries, but little information is available about their associated microbial community. One hundred and fifty-seven bacterial isolates were isolated from 62 Assam tea leaf samples collected from 6 provinces of Northern Thailand and classified within the phyla of Firmicutes, Actinobacteria, and Proteobacteria. Phayao and Phrae provinces exhibited the highest and the lowest bacterial diversities, respectively. The bacterial community structural pattern demonstrated significant differences between the west and the east sides. Since some Bacillus spp. have been reported to be involved in fermented Miang, Bacillus spp. isolated in this study were chosen for further elucidation. Bacillus siamensis ML122-2 exhibited a growth inhibitory effect against Staphylococcus aureus ATCC 25923 and MRSA DMST 20625, and the highest survival ability in simulated gastric and intestinal fluids (32.3 and 99.7%, respectively), autoaggregation (93.2%), cell surface hydrophobicity (50.0%), and bacterial adherence with Vero cells (75.8% of the control Lactiplantibacillusplantarum FM03-1). This B. siamensis ML122-2 is a promising probiotic to be used in the food industry and seems to have potential antibacterial properties relevant for the treatment of antibiotic-resistant infections.

Corporate Responsibility for Human Rights in Assam Tea Plantations: A Business and Human Rights Approach

This paper explores how UK-based companies deal with their responsibility to respect the human rights of Assam (India) tea plantation workers. Through qualitative content analysis of publicly available corporate reports and other documents, it investigates how companies approach and communicate their potential human rights impacts. It highlights the gap between well-documented human rights issues on the ground and corporate reports on these issues. It aims to answer the following research question: in a context where the existence of human rights violations at the end of the supply chain is well-documented, how do companies reconcile their possible connection with those violations and the corporate responsibility to respect human rights under the United Nations Guiding Principles on Business and Human Rights? This paper reveals the weakness of the current corporate social responsibility (CSR) approach from the perspective of rights-holders. It supports a business and human rights approach, one that places the protection of human rights at its core.

Evaluation of Multifarious Plant Growth Promoting Trials of Yeast Isolated from the Soil of Assam Tea (Camellia sinensis var. assamica) Plantations in Northern Thailand

Some soil microorganisms, especially bacteria and mycorrhizal fungi, play a role in the promotion of plant growth. However, plant growth promotion involving yeasts in soil has not yet been extensively investigated. This study aimed to isolate and identify yeast strains obtained from soils of the Assam tea plant (Camellia sinensis var. assamica) in northern Thailand and to investigate their plant growth promoting capabilities. A total of 42 yeast strains were obtained and identified by analysis of the D1/D2 domain of the large subunit ribosomal RNA gene. We identified 35 strains of six species belonging to the phylum Ascomycota, namely Aureobasidium melanogenum, Kazachstania aquatica, Saturnispora diversa, Saturnispora sekii, Schwanniomyces pseudopolymorphus and Wickerhamomyces anomalus, and six species were determined to belong to the phylum Basidiomycota, namely Apiotrichum scarabaeorum, Curvibasidium pallidicorallinum, Papiliotrema laurentii, Rhodosporidiobolus ruineniae, Trichosporon asahii and Trichosporon coremiiforme. Seven strains were representative of potential new species and belonged to the genera Galactomyces and Wickerhamomyces. A total of 28 strains were found to produce indole-3-acetic acid (IAA) in a range of 2.12 to 37.32 mg/L, with the highest amount of IAA produced by R. ruineniae SDBR-CMU-S1-03. All yeast strains were positive in terms of ammonia production, and only eight strains were positive for siderophore production. Two yeast species, P. laurentii and W. anomalus, were able to solubilize the insoluble form of calcium and zinc. The ability to produce amylase, endogulcanase, lipase, pectinase, protease and xylanase was dependent upon the yeast species and strain involved.