The morphology of the two varieties of BC membrane surfaces
were characterised by SEM (ISM-6390LV, JEOL, Japan).
The 60 ◦C-dried samples were coated with approximately 20 nm
gold–palladium before observation. The samples were measured
using the SEM with a sputtered time of 30 s and an accelerating
voltage of 15 kV. Images with 5000× and 10,000× magnification
were recorded.