The fungal pathogen Candida albicans autoinduces hyphal morphogenesis by raising extracellular pH.
Level 5 - mechanism / opinion, no new human data
Bench research / in vitro laboratory and genetic study
PubMed 21586647 · doi:10.1128/mBio.00055-11
What was done
Method and design, investigated extracellular pH modulation by the fungal pathogen *Candida albicans* under carbon-deprived (glucose-poor) conditions with exogenous amino acids. Using physiological assays, genomic analyses, and targeted gene mutations (*STP2*, *ACH1*, *DUR1,2*, and *ATO5*), the authors analyzed amino acid catabolism, ammonia extrusion, and subsequent yeast-to-hyphal morphological switching.
What was found
Under acidic conditions with low glucose and available amino acids, *C. albicans* raised extracellular pH from 4 to >7 in less than 12 hours. This alkalinization was driven by amino acid uptake and catabolism as a cellular carbon source, resulting in ammonia extrusion that autoinduced hyphal morphogenesis. Mutations in *STP2*, *ACH1*, *DUR1,2*, and *ATO5* abolished or delayed environmental neutralization. The abstract reports no other numerical values or error estimates.
Why it matters
This study defines a mechanism by which *C. albicans* actively remodels acidic microenvironments via amino acid catabolism and ammonia extrusion, directly triggering the switch to invasive hyphae.
Limits
The study is entirely in vitro bench and genetic research with no direct in vivo host infection data presented in the abstract. Quantitative variance, sample sizes, and replicate numbers are omitted from the abstract.
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