Gametophytes of the fern Ceratopteris richardii may be either hermaphrodites or males.  Hermaphrodites contain both archegonia and antheridia as well as rhizoids, while the male contains antheridia and rhizoids.  The presence of a hermaphrodite-secreted hormone called antheridiogen (ACE) influences individuals to develop as males (male induction), while its absence leads to hermaphrodite development.  The continued presence of ACE is required to maintain the male program.  Removal of the male from ACE leads to conversion of the male to a hermaphrodite.  A soil bacterium, Pseudomonas nitroreducens, has been shown to increase the proportion of gametophytes that are hermaphroditic in culture and to increase the length of rhizoids in both hermaphrodites and males.  Here we investigate the effects of other soil bacteria on rhizoid development, male induction, and conversion.  Thirteen soil bacteria (8 gram negative and 5 gram positive), isolated from fern roots, were tested for their effect on rhizoid growth.  Preliminary experiments for six of these soil bacteria (4 gram negative and 2 gram positive) were also performed to determine potential effects on fern sex determination.  One gram-negative soil bacterium, P. nitroreducens, was tested for its effect on time to conversion.  In general, gram-negative bacteria were more likely to increase rhizoid length and increase the proportion of hermaphrodites in culture.  P. nitroreducens shortened the time to conversion.  Overall, bacteria that resulted in longer rhizoids also concurrently increased the percentage of hermaphrodites in culture.