The ΔdagB mutant had little effect on growth relative to wild type in minimal media containing either KC or IC; however, the ΔdagA3 mutant showed a significant growth delay and the double ΔdagA3/ΔdagB mutant abolished growth altogether, confirming the importance of these α-1,3-(3,6-anhydro)-d-galactosidases in carrageenan degradation (Fig. 6a, b). This evidence concerns the gene IGKV2D-18 and keratoconus.