Microbial ecology

This study examines prevalence of antibiotic resistant bacteria in Amazon parrots in three different groups, one wild and two captive. Commensal bacteria were isolated from 24 parrots and screened for antibiotic resistance. Culture-based and molecular methods were used and a total of 546 isolates from the genus Staphylococcus and Rothia were obtained. Antibiotic resistance was found in all parrot groups in 161 isolates with 48 having multi-drug resistance. The highest frequency of resistance was found to Enrofloxacin and Amoxicillin/Clavulnate though all antibiotics tested were resisted by some bacterial isolates. Both captive groups exhibited more resistant individuals than the wild. This study concluded that antibiotic resistant commensal bacteria in Amazons are common; however, patterns found cannot be explained by antibiotic use. A high rate of multi-drug resistance was detected in more common mannitol non-fermenting Staphylococcus spp., and drug resistant detected in Rothia spp. may indicate a future role in disease.

Atrazine is a popular herbicide used in over 80 countries to inhibit the growth of broadleaf and grassy weeds. Atrazine is a common pollutant in soil and groundwater, and high concentrations of atrazine cause developmental defects in fish, amphibians, and birds. The bacteria Pseudomonas sp. strain ADP (P.ADP) uses atrazine as a nitrogen source by transforming atrazine to ammonia through a number of enzymatic reactions. In this project I measured the growth and atrazine degradation of P.ADP in media with atrazine as the sole nitrogen source. A mutant strain isolated after mutagenesis with UV light showed faster growth and reached higher densities than the control strain. A series of mating experiments were performed to determine whether the growth mutation was on the atrazine degrading plasmid or in the chromosome. The limitations and potential of P.ADP for atrazine degradation are discussed.