Kombucha bacterial cellulose (KBC), a by-product of kombucha fermentation, can be used as a biomaterial for microbial immobilization. In this study, we investigated the properties of KBC produced from green tea kombucha fermentation on days 7, 14, and 30 and its potential as a protective carrier of Lactobacillus plantarum, a representative beneficial bacteria. The highest KBC yield (6.5%) was obtained on day 30. Scanning electron microscopy showed the development and changes in the fibrous structure of the KBC over time. They had crystallinity indices of 90–95%, crystallite sizes of 5.36–5.98 nm, and are identified as type I cellulose according to X-ray diffraction analysis. The 30-day KBC had the highest surface area of 19.91 m²/g, which was measured using the Brunauer–Emmett–Teller method. This was used to immobilize L. plantarum TISTR 541 cells using the adsorption–incubation method, by which 16.20 log CFU/g of immobilized cells was achieved. The amount of immobilized L. plantarum decreased to 7.98 log CFU/g after freeze-drying and to 2.94 log CFU/g after being exposed to simulated gastrointestinal tract conditions (HCl pH 2.0 and 0.3% bile salt), whereas the non-immobilized culture was not detected. This indicated its potential as a protective carrier to deliver beneficial bacteria to the gastrointestinal tract.

Hydrogen sulfide (H₂S) is a toxic and corrosive component that commonly occurs in biogas. In this study, H₂S removal from swine-waste biogas using sulfur-oxidizing Paracoccus versutus CM1 immobilized in porous glass (PG) and polyurethane foam (PUF) biofilters was investigated. Bacterial compositions in the biofilters were also determined using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The biofilters were first tested on a laboratory scale under three space velocities (SV): 20, 30, and 40 h⁻¹. Within 24 h, at an SV of 20 h⁻¹, PG and PUF biofilters immobilized with P. versutus CM1 removed 99.5% and 99.7% of H₂S, respectively, corresponding to the elimination capacities (EC) of 83.5 and 86.2 gm⁻³ h⁻¹. On a pilot scale, with the horizontal PG-P. versutus CM1 biofilter operated at an SV of 30 h⁻¹, a removal efficiency of 99.7% and a maximum EC of 113.7 gm⁻³ h⁻¹ were achieved. No reduction in methane content in the outlet biogas was observed under these conditions. The PCR-DGGE analysis revealed that Paracoccus, Acidithiobacillus, and Thiomonas were the predominant bacterial genera in the biofilters, which might play important roles in H₂S removal. This PG–P. versutus CM1 biofiltration system is highly efficient for H2S removal from swine-waste biogas.