A Modification of Brilliant Green Agar for Improved Isolation of Salmonella

Five organisms commonly found to be capable of growth on commercial Brilliant Green Agar (BGA) after enrichment in Muller-Kauffman Tetrathionate broth (MKT) were tested for sensitivity to 18 antimicrobial agents. The sensitivities of two Salmonella serotypes to these agents were also tested. A combination of sulphacetamide (at 1.0 mg/ml) and mandelic acid (at 0.25 mg/ml) incorporated into BGA was found to give maximum recovery of salmonellas from MKT broth enrichment whilst giving maximum suppression of contaminating organisms. More importantly, this Antibiotic-enriched Brilliant Green Agar (ABG) gave a lower incidence of false positive results when compared with commercial BGA. Increasing the incubation temperature from 35 to 43°C was found to accentuate the selectivity of ABG without inhibiting the growth of salmonellas. A total of 31 Salmonella serotypes were tested for their ability to grow on ABG at 43°C; all produced typical colonies.     

Remarkable leaf anatomical variations in Neurachne and its allies (Poaceae) in relation to G3 and G4 photosynthesis

The leaf blade anatomy of all species of Neurachne, Paraneurachne and Thyridolepis has been examined, with special reference to features reliably indicative of photosynthetic pathway. Neurachne alopecuroidea, N. queenslandica and N. tenuifolia exhibit C₃ anatomy, as do all three Thyridolepis species. Paraneurachne muelleri, N. munroi and N. minor all have C₄ anatomy, of the rare ' Alloteropsis-type'. However, all the species exhibit unusual anatomical features, and N. lanigera cannot be confidently assigned as C₃ or C, on anatomical grounds alone. Taxonomic considerations confirm that the three genera are closely related to one another in the context of the eu-panicoid assemblage as a whole, and that the genus Neurachne itself, although it exhibits variation in photosynthetic pathway, is not amenable to further taxonomic subdivision.