Objective   Microorganisms that can efficiently decompose tea dregs at high temperature were screened for potential waste treatment application.

  Method   A high temperature special habitat separation method was employed to isolate cellulase and protease-producing bacteria on tea dregs. Morphological, physiochemical, and growth characteristics of selected strains were examined prior to 16S rDNA cloning for sequencing. Gene sequences of the candidates, along with gyrB, were subjected to phylogenetic analysis for species identification. Decomposing capacity of the isolated strains on tea dregs was determined for final selection.

  Results   Five thermophiles exhibiting the desired properties were isolated. Among them, Fb showed the highest enzymatic activities and was found to be a strain of Bacillus velezensis. It was further characterized with a high temperature tolerance up to 55 ℃ and the optimal culture conditions of 42-45 ℃, pH 5.0-7.0, 16 h incubation, 1.0-6.0% salinity, 30 mL 250 min⁻¹ filling volume, and 120 rpm shaker speed. After Fb inoculation and incubation for 7 d, the crude protein in the resulting tea dregs significantly increased by 14.88% (P＜0.05), the contents of 14 amino acids, except cystine, methionine, and histidine, significantly increased (P＜0.05), the total amino acids increased by 5.98%, the crude fiber decreased by 9.69%, and the neutral detergent fiber, acid detergent fiber, and lignin decreased by 10.72%, 4.47%, and 11.37%, respectively (P＜0.05).

  Conclusion  For the first time, B. velezensis Fb was identified to be capable of efficiently decomposing tea dregs with a significantly improved nutritional profile on the substrate. It could conceivably become a bioagent for treating the waste material.