Biochemical, nutrient and inhibitory characteristics of Streptomyces cultured from a hypersaline estuary, the laguna Madre (Texas)

Streptomyces are common soil bacteria that produce secondary metabolites, including several antibiotics; however, the characteristics of marine Streptomyces are largely unknown. Sediment samples were taken from 3 sites in the Laguna Madre to isolate marine Streptomyces. Sediment was diluted, spread onto synthetic seawater media to estimate the total bacterial density of the samples and spread onto starch casein agar to isolate Streptomyces. Isolated Streptomyces were tested for salinity tolerance and optimal growth pH. Isolates were assayed using API 20E® test strips and BIOLOG™ plates to construct biochemical profiles and assess nutrient utilization abilities of the bacteria, respectively. Individual Streptomyces were tested for the ability to inhibit the growth of other isolated Streptomyces (i.e., interference competition) and putatively identified by DNA sequencing. Results showed that there was no significant difference in microbial density in sediments from the 3 sampling sites. Eleven (11) Streptomyces pure cultures were obtained in total; most tolerated salinity up to 60 ppt and grew optimally at pH 7.5. Biochemical profile comparisons showed that the Streptomyces were only at least 74% similar; most (8/11) were \u3e90% similar. Isolates could use between 87-95 carbon sources. Three (3) isolates displayed interference toward other isolates. Ten (10) isolates were identified as Streptomyces griseus by DNA sequencing. Laguna Madre Streptomyces organisms display some diverse characteristics with regards to their halotolerance, biochemical profiles, carbon source utilization and inhibition toward other organisms. Further investigations may yield greater understanding of these organisms in this and other marine environments and may be a reservoir of novel microorganisms and secondary metabolites

Evaluating the long-term storage of Cryphonectria parasitica

Isolates of the Chestnut blight pathogen, Cryphonectria parasitica, from six populations in Michigan, were stored in the late 1990s as agar plugs of mycelium in vials of sterile water held at room temperature. Approximately 29% of the fungal isolates were infected with mycoviruses at the time of storage. Each isolate was tested for revivification effectiveness by taking aliquots from vials filled with agar plugs of C. parasitica and sterile water and plating onto potato dextrose agar. Average revivification success was 70.5% across populations with a range of 33—84% within populations. In situations where vials had dried out during storage, success was low (4%), while success for vials that retained sterile water averaged 90%. Most importantly however, is the loss of mycoviruses from stored isolates; only 2 of 119 stored mycovirus infected isolates still contained mycoviruses after storage, suggesting that the double-stranded RNA mycoviruses are degraded during storage