Some KTs, such as K1 and K28 from Saccharomyces cerevisiae, have a narrow spectrum of activity, limited to susceptible strains of the same species, while other KTs show a wide killing spectrum . In particular, some Wickerhamomyces anomalus (formerly Pichia anomala) KTs proved to be active against a wide range of microorganisms, including other yeast species, filamentous fungi, bacteria, and protozoan parasites .