A proposal for three biotypes of the pathogenic alga Prototheca zopfii, and standards for their identification

Colorless algae of the genus Prototheca out of the family of Chlorellaceae have been identified to be the only known plant causative agents of infections in humans and animals.Recently, the recognition of distinct phenotypic clusters have been reported as assigned as "variants'. A representative selection of Prototheca (P.) zopfii strainsisolated from different environmental habitats or clinical cases was characterised in a polyphasic approach in order to assess their intraspecies taxonomic position.The P. zopfii- strains were compared by a number of phenotypic and genetic criteria, including growth characteristics, biochemical reactions, and serotypingresults. Based on emended standards for biotype identification P, zopfii strains showed auxanographical differences and distinct assimilation patterns withrespect to utilization of amino acids and glycerol.