A method for growth and immobilisation of Streptococcus faecalis var. zymogenes in bioreactors containing hollow-fibre, ceramic, metallic or glass-fibre membranes

Details are given for the design, construction, operation, analysis, monitoring and control of microbial bioreactors fabricated from a variety of artificial membranes. The types of membranes used were polysulphone or glass hollow fibres and ceramic or metallic tubular constructs. Growth of Streptococcus faecalis var. zymogenes and the level of formation of the major metabolic end products (lactate and acetate) are reported for each bioreactor type. Satisfactory growth was obtained in each system. There was less end-product formation and growth in the bioreactor constructed from glass-fibres than in the other systems. The ratio of lactate:acetate produced suggested that the bacteria were growing largely in an oxygen limited environment in the matrices of all the membrane systems. Variation in the level of aeration in the feed to the polysulphone hollow-fibre and tubular ceramic bioreactors confirmed that there was poor mass transfer of gas to the dense cultures of bacteria in all the membrane matrices.