An Analysis of Stenotrophomonas Chitinase Variation and Its Impact on Batrachochytrium dendrobatidis Growth Inhibition
The bacterial species Stenotrophomonas rhizophila and S. maltophilia live in the skin microbiome of the eastern redback salamander (Plethodon cinereus), and secrete metabolites that inhibit the deadly chytrid fungus’s, Batrachochytrium dendrobatidis (Bd), growth. Despite the importance of these metabolites in suppressing Bd growth, the genes encoding them have been largely unstudied, especially in S. rhizophila. Because chitinases have been shown to inhibit fungal growth, chitinase variation was analyzed in S. rhizophila and S. maltophilia isolates collected from eight P. cinereus individuals sampled in the New York City metropolitan area (NY, USA). Variation among the nucleotide and amino acid sequences, respectively, were compared to differences among isolates’ antifungal abilities. The complete chitinase gene was sequenced for four S. rhizophila and two S. maltophilia isolates, while a partial family 18 glycoside hydrolase (GH18) sequence from four additional S. rhizophila isolates was obtained. Despite this sample size, substantial variation was observed among the complete chitinases, with S. rhizophila and S. maltophilia isolates’ genes differing up to 11.4% and 24.7%, and their amino acid sequences diverging up to 8.9% and 28.2%, respectively. However, the changes did not correlate with differences in antifungal ability observed in functional assays. Evidence of a duplicated GH18 motif was found in two isolates, indicating that S. rhizophila may have a partially copied endochitinase gene. This is the first study to report the complete chitinase sequence of multiple Stenotrophomonas isolates from P. cinereus, providing insight into Stenotrophomonas antifungal ability, and in the future, may be used to improve disease resistance.
Lally, Mary Catherine, "An Analysis of Stenotrophomonas Chitinase Variation and Its Impact on Batrachochytrium dendrobatidis Growth Inhibition" (2021). ETD Collection for Fordham University. AAI28494344.