In this case study, we compare the performance of an enzyme immobilised using two different methods: i) as carrier-free catalytically active inclusion bodies or ii) as carrier-attached immobilised enzyme. To make this comparison we used a trehalose transferase from Thermoproteus uzoniensis fused to the fluorescent thermostable protein mCherry. The fusion of mCherry to trehalose transferase allowed direct spectrophotometric quantification and visualisation of the enzyme in both native and denatured states. The catalytically active inclusion bodies outperformed the immobilised enzyme in their simplicity of biocatalyst production resulting in high enzyme productivity. Enzyme immobilised on carrier materials showed a higher catalytic activity and a more robust performance under batch process conditions.@en