Four tropical lucinids, Codakia orbiculata, C. pectinella, Linga pensylvanica, which inhabit sea‐grass beds, and Lucina pectinata, which inhabits mangrove swamps, harbor sulfur‐oxidizing endosymbiotic bacteria within bacteriocytes of their gill filaments. To elucidate the symbiont transmission mode in these bivalves, symbiont‐specific oligonucleotides were designed and used in polymerase chain reaction amplifications (PCR). For all species investigated, each primer set was unsuccessful in amplifying symbiont DNA targets from ovaries and testis, whereas successful amplifications were obtained from symbiont‐containing gill tissue. These data suggest that the transmission mode is environmental, independently of the lucinid habitat, as it is in the other tropical lucinid Codakia orbicularis.

The detection of acidophilic microorganisms from mining environments by culture methods is time consuming and unreliable. Several PCR approaches were developed to amplify small-subunit rRNA sequences from the DNA of six bacterial phylotypes associated with acidic mining environments, permitting the detection of the target DNA at concentrations as low as 10 fg.