Cell separation of Haemophilus influenzae type b through tangential microfiltration

Abstract

Centrifugation techniques are frequently used to separate bacteria from the culture broth in pharmaceutical industries. Alternatively, cell separation can be performed through tangential microfiltration systems; an arguably cost-effective alternative to centrifugation. Therefore, replacement of centrifugation steps with microfiltration represents an attractive option in order to decrease production costs. An example of such use can be found in the production of the vaccine against Haemophilus influenzae type b (Hib), which relies on a centrifugation step to separate the pathogenic bacteria from the antigen-rich (exopolysaccharide) released into culture broth. The substitution of the centrifugation operation with tangential microfiltration may decrease production costs and increase vaccine availability in low-income regions. Hence, we studied the impact of diverse microfiltration systems at different production scales in the separation of Hib from its culture broth. The recovery of the exopolysaccharide - polyribosylribitol phosphate (PRP), the antigen employed in the vaccine, produced by Hib and present in the culture broth was used as a read-out for process efficiency. In sum, the use of Hydrophilic Polyvinylidene Fluoride (PVDF) membranes resulted in the highest recovery value among the tested materials; moreover, the transmembrane pressure was a paramount factor determining the recovery level. We concluded that Hib cell separation through tangential microfiltration systems represents a feasible alternative to centrifugation.