Isolation and Molecular Identification of Bacteria Associated with Commercial Tea Brands in Al-Bayda, Libya

Abstract

Dried tea is a low-moisture plant product in which microbial growth is limited, but viable bacteria may persist through cultivation, harvesting, processing, transport and storage. This study isolated and identified culturable bacteria from five commercial tea products sold in Al-Bayda, Libya: two green teas (Nabet and Al-Jawhara) and three red/black teas (Al-Ghazaleen, Al-Baraka and Zahra red/black tea). One gram of each product was suspended in 9 mL of sterile 0.85% saline, serially diluted and spread on nutrient agar, and plates were incubated at 30°C for 24 h. Seven morphologically distinct colonies (T1–T7) were purified and characterised by colony morphology and Gram staining, and the 16S rRNA gene was amplified by PCR, sequenced by the Sanger method and compared with NCBI records using BLAST. All isolates were rods; T1, T4 and T6 were Gram-positive and T2, T3, T5 and T7 were Gram-negative. The isolates were assigned to Psychrobacillus psychrodurans (T1; PV000778), Pseudomonas palmensis (T2; PV000779), P. kilonensis (T3; PV000780), Priestia megaterium (T4; PV000781), P. fragi (T5; PV000782), Bacillus cereus (T6; PV000783) and Sphingobacterium anhuiense (T7; PV000784), with accession numbers reported as PV000778–PV000784; their live records and correspondence with the isolates should be verified before submission. The assemblage combines endospore-forming bacteria, pseudomonads and a genus typical of soil and water, which is consistent with several possible routes of contamination along the supply chain. Because selected isolates were examined without viable counts or toxin tests, the study documents the presence of culturable bacteria but not their abundance, prevalence or risk to consumers. The deposited sequences provide a reference for quantitative studies of tea microbiology in Libya.