Anabaena flos-aquae NRC 525-17 produces a very potent neurotoxin, anatoxin-a(s). During isolation of the neurotoxin, we found that the strain contains four other toxic compounds which show strong hepatotoxicity. The four toxins, toxins 1, 1', 2, and 3, were successfully purified. Toxin 2, one of major toxins, was identified as 3-desmethylmicrocystin LR (1) by comparison of spectral data of the known compound. Since the three other toxins contain an unknown amino acid, GC/MS was applied and it revealed the presence of homotyrosine in toxins 1 (2) and 1' (3). Only a partial structure was obtained for toxin 3 due to the small amount present in the cells.

Microbial growth rates in subsurface sediment from three sites were measured using incorporation of tritiated thymidine into DNA. Sampling sites included Lula, Oklahoma, Traverse City, Michigan, and Summit Lake, Wisconsin. Application of the thymidine method to subsurface sediments required (1) thymidine concentrations greater than 125 nM, (2) incubation periods of less than 4 hours, (3) addition of SDS and EDTA for optimum macromolecular extraction, and (4) DNA purification, in order to accurately measure the rate of thymidine incorporation into DNA. Macromolecule extraction recoveries, as well as the percentage of tritium label incorporated into the DNA fraction, were variable and largely dependent upon sediment composition. In general, sandy sediments yielded higher extraction recoveries and demonstrated a larger percentage of label incorporated into DNA than sediments that contained a high silt-clay component. Reported results also indicate that the acid-base hydrolysis procedure routinely used for macromolecular fractionation in water samples may not be routinely applicable to the modified sediment procedure where addition of SDS and EDTA are required for macromolecule extraction. Growth rates exhibited by subsurface communities are relatively slow, ranging from 5.1 to 10.2×10(5) cells g(-1) day(-1). These rates are 2-1,000-fold lower than growth rates measured in surface sediments. These data lend support to the supposition that subsurface microbial communities are nutritionally stressed.