Substrate type and microbial interactions as factors affecting ascocarp formation by mangrove fungi

The growth and ascocarp formation of Aigialus parvus, Lignincola laevis and Verruculina enalia in single and mixed cultures on wood of Avicennia alba, Bruguiera cylindrica and Rhizophora apiculata was studied. In pure cultures, these fungi grew well on all three species of wood. Except for Aigialus parvus on B. cylindrica, all three fungi also formed abundant ascocarps. The time needed for ascocarp formation after inoculation ranged from six to eight weeks for L. laevis on all wood species, and for V. enalia on Avicennia alba; to ten weeks for V. enalia on B. cylindrica and R. apiculata; and 12 weeks for Aigialus parvus on Avicennia alba and R. apiculata. Mixed cultures involving two or three of the test fungi delayed the onset of sporulation and affected the abundance of ascocarps formed. Sporulation by Aigialus parvus on Avicennia alba and R. apiculata was markedly reduced by L. laevis alone or in combination with V. enalia. Likewise, sporulation by L. laevis was suppressed by Aigialus parvus and/or V. enalia. In contrast, the presence of L. laevis enhanced ascocarp formation by V. enalia on all types of wood. These observations suggest the presence of interference competition among the test fungi.