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

Vipanee Chumsai-Na-Ayudhya,Chaowarin Yodsombat,Patthanasak Rungsirivanich,Witsanu Supandee,Narumol Thongwai,Wirapong Futui

doi:10.3390/microorganisms8101585

Vipanee Chumsai-Na-Ayudhya, Chaowarin Yodsombat + Show 4 more

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https://doi.org/10.3390/microorganisms8101585

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Abstract

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 Lactiplantibacillus plantarum 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.

Highlights

Assam tea (Camellia sinensis var. assamica) or “Miang”, as called by Northern Thai people, is a perennial native plant from the highlands of Northern Thailand, i.e., Chiang Mai, Chiang Rai, Lampang, Nan, Phayao, and Phrae provinces, and neighbor countries [1,2]
Assam tea plants or Camellia sinensis var. assamica are widely found in the highlands of Northern Thailand at altitudes over 200 m above sea level
The microbial composition of Assam tea leaves in Thailand first described by Rungsirivanich et al [11] revealed the presence of culturable bacteria from the genera Bacillus, Floricoccus, Kocuria, Lysinibacillus, Micrococcus, and Staphylococcus

Summary

Introduction

Assam tea (Camellia sinensis var. assamica) or “Miang”, as called by Northern Thai people, is a perennial native plant from the highlands of Northern Thailand, i.e., Chiang Mai, Chiang Rai, Lampang, Nan, Phayao, and Phrae provinces, and neighbor countries [1,2]. The bacterial community on Assam tea leaves from the tea gardens in Nan province of Thailand revealed by Rungsirivanich et al [11] consisted of the genera Bacillus, Floricoccus, Kocuria, Lysinibacillus, Micrococcus, and Staphylococcus. Bacillus licheniformis, Bacillus siamensis, and Bacillus tequilensis were pointed as important elements for biological control during leaf fermentation by inhibiting the growth of food spoilage and pathogenic microbes [12]. In this gut microbiome era, sources of probiotics are intensely studied, and the Assam tea plant and its products have proved to be notable

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