Quantitation of Purines from Pigeon Guano and Implications for Cryptococcus neoformans Survival During Infection
The fertilizing properties of bird manure, or guano, have played an important role in plant cultivation for thousands of years. Research into its chemical composition by Unger in 1846 identified a novel compound, now known as guanine, a purine base that is essential for DNA and RNA biosynthesis and cell signalling. Nitrogen-rich guano can also harbour human pathogens, one significant example being the fungal pathogen Cryptococcus neoformans. Historically associated with pigeon droppings, C. neoformans is able to infect immunocompromised individuals with the aid of a number of adaptive virulence traits. To gain insight into this niche, a quantitative analysis of pigeon guano was performed by LC/MS to determine the concentrations of purines present. Guanine was found in abundance, in particular, in aged guano samples that contained 156–296 μg/g [w/w] compared to 75 μg/g in fresh guano. Adenine concentrations were more consistent between fresh and aged samples, 13 μg/g compared to 10–15 μg/g, respectively. C. neoformans strains that lack key enzymes of the de novo purine synthesis pathway and are guanine or adenine auxotrophs displayed differences in their ability to exploit this substrate: growth of a guanine auxotrophic mutant (gua1Δ) was partially restored on 30% pigeon guano media, but an adenine auxotrophic mutant (ade13Δ) was unable to grow. We conclude that while purine salvage is likely a useful resource-saving mechanism, alone it is not sufficient to fully provide the purines required by wild-type C. neoformans growing in its guano niche.
KeywordsCryptococcus neoformans Purines Pigeon guano Adenine Guanine
We thank Gary Newell of the Queensland Racing Pigeon Federation, Inc., for the provision of pigeon guano.
This study was funded by National Health and Medical Research Council, Project Grant APP1049716.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 1.The Guano Isles. Perrysburg J. 1855.Google Scholar
- 2.Republics BotIUotA. Bulletin of the International Union of the American Republics. H doc 163. Washington; 1909.Google Scholar
- 4.Sanfelice F. Sull’azione patogena dei bastomiceti. Ann Isto Igiene R Univ Roma. 1895;5:239–62.Google Scholar
- 5.Busse O. Uber parasitäre Zelleinschlüsse und ihre Zeichnung. Zentralbl Bakt Parasit 1894:16.Google Scholar
- 6.Vuillemin P. Les blastomycetes pathogenes. Revue Generale des Sciences Pures et Appliquees. 1901;12:732–51.Google Scholar
- 8.Staib F. Vogelkot, Ein Nahrsubstrat Fur Die Gattung Cryptococcus. Zbl Bakt Parasit. 1962;186(2):233–47.Google Scholar
- 9.Rosario Medina I, Roman Fuentes L, Batista Arteaga M, Real Valcarcel F, Acosta Arbelo F, Padilla Del Castillo D, et al. Pigeons and their droppings as reservoirs of Candida and other zoonotic yeasts. Revista Iberoamericana de Micologia. 2017. https://doi.org/10.1016/j.riam.2017.03.001.CrossRefPubMedGoogle Scholar
- 10.Costa AK, Sidrim JJ, Cordeiro RA, Brilhante RS, Monteiro AJ, Rocha MF. Urban pigeons (Columba livia) as a potential source of pathogenic yeasts: a focus on antifungal susceptibility of Cryptococcus strains in Northeast Brazil. Mycopathologia. 2010;169(3):207–13. https://doi.org/10.1007/s11046-009-9245-1.CrossRefPubMedGoogle Scholar
- 13.Ellabib MS, Aboshkiwa MA, Husien WM, D’Amicis R, Cogliati M. Isolation, identification and molecular typing of Cryptococcus neoformans from pigeon droppings and other environmental sources in Tripoli, Libya. Mycopathologia. 2016;181(7–8):603–8. https://doi.org/10.1007/s11046-016-9996-4.CrossRefPubMedGoogle Scholar
- 16.Staib F, Seeliger HP. A new selective medium for the isolation of C. neoformans from fecal material and from soil. Ann Inst Pasteur (Paris). 1966;110(5):792–3.Google Scholar
- 26.Chitta R, Pendela M, Yekkala R, Herijgers P, Hoogmartens J, Adams E. Determination of adenosine and inosine in sheep plasma using solid phase extraction followed by liquid chromatography with UV detection. Anal Lett. 2010;43(14):2267–74. https://doi.org/10.1080/00032711003717323.CrossRefGoogle Scholar
- 27.Shi J, Liu HF, Wong JM, Huang RN, Jones E, Carlson TJ. Development of a robust and sensitive LC-MS/MS method for the determination of adenine in plasma of different species and its application to in vivo studies. J Pharm Biomed Anal. 2011;56(4):778–84. https://doi.org/10.1016/j.jpba.2011.07.023.CrossRefPubMedGoogle Scholar
- 28.Simmonds HA, Duely JA, Davies PM. Analysis of purines and pyrimidines in blood, urine, and other physiological fluids. Techniques in diagnostic human biochmeical genetics. New York: Wiley; 1990. p. 397–424.Google Scholar
- 30.Chitty JL, Blake KL, Blundell RD, Koh Y, Thompson M, Robertson AAB, et al. Cryptococcus neoformans ADS lyase is an enzyme essential for virulence whose crystal structure reveals features exploitable in antifungal drug design. J Biol Chem. 2017;292(28):11829–39. https://doi.org/10.1074/jbc.M117.787994.CrossRefPubMedPubMedCentralGoogle Scholar
- 31.Vega GIdl. Primera parte de los com entarios reales de los Incas. 1609.Google Scholar
- 32.Boston Society of Natural History. In: Proceedings of the Boston Society of Natural History, vol 1. Boston: Dutton and Wentworth; 1841.Google Scholar