A Wickerhamomyces anomalus killer strain in the malaria vector Anopheles stephensi.
The yeast Wickerhamomyces anomalus has been investigated for several years for its wide biotechnological potential, especially for applications in the food industry. Specifically, the antimicrobial activity of this yeast, associated with the production of Killer Toxins (KTs), has attracted a great deal of attention. The strains of W. anomalus able to produce KTs, called "killer" yeasts, have been shown to be highly competitive in the environment. Different W. anomalus strains have been isolated from diverse habitats and recently even from insects. In the malaria mosquito vector Anopheles stephensi these yeasts have been detected in the midgut and gonads. Here we show that the strain of W. anomalus isolated from An. stephensi, namely WaF17.12, is a killer yeast able to produce a KT in a cell-free medium (in vitro) as well as in the mosquito body (in vivo). We showed a constant production of WaF17.12-KT over time, after stimulation of toxin secretion in yeast cultures and reintroduction of the activated cells into the mosquito through the diet. Furthermore, the antimicrobial activity of WaF17.12-KT has been demonstrated in vitro against sensitive microbes, showing that strain WaF17.12 releases a functional toxin. The mosquito-associated yeast WaF17.12 thus possesses an antimicrobial activity, which makes this yeast worthy of further investigations, in view of its potential as an agent for the symbiotic control of malaria.
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Alessia
A
Cappelli
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Ulisse
U
Ulissi
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Matteo
M
Valzano
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Claudia
C
Damiani
Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Università degli Studi di Milano, Milan, Italy.
Sara
S
Epis
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Maria Gabriella
MG
Gabrielli
Dipartimento di Scienze Biomediche, Biotecnologiche e Traslazionali, Università degli Studi di Parma, Parma, Italy.
Stefania
S
Conti
Dipartimento di Scienze Biomediche, Biotecnologiche e Traslazionali, Università degli Studi di Parma, Parma, Italy.
Luciano
L
Polonelli
Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Università degli Studi di Milano, Milan, Italy.
Claudio
C
Bandi
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Guido
G
Favia
Scuola di Bioscienze e Medicina Veterinaria, Università degli Studi di Camerino, Camerino, Italy.
Irene
I
Ricci
D000818:Animals; D000852:Anopheles / Q000382:microbiology*; D005260:Female; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D007303:Insect Vectors / Q000382:microbiology*; D008288:Malaria / Q000635:transmission; D009183:Mycotoxins / Q000378:metabolism; D004718:Saccharomycetales / Q000302:isolation & purification* / Q000378:metabolism
D005656:Fungal Proteins; D009183:Mycotoxins