Abstract Avocado represents one of the most nutritious and consumed foods in Mexico, and its export generates significant profits; because of its fatty acids content, the avocado oil was used as an inducer for the synthesis of extracellular lipases from the non-conventional yeast Kluyveromyces marxianus L-2029. Lipases are able to catalyze acyl glycerides, hydrolyzing them into fatty acids and glycerol; they have several applications in various industries. In order to determine the ideal initial avocado oil concentration in the culture medium for the yeast, the induction was carried out at different concentrations in incubation for 24 h. The yeast presented the greater extracellular lipase productivity at a 3.5% v/v avocado oil concentration, with a 3.47 μmol PNF/mg prot * min (U/mL) maximum activity. The enzymatic extract obtained at this condition had an optimum lipase activity temperature of 36 °C and pH 6. The pYJR10W lipase was detected in the enzymatic extract from avocado oil induction, and is therefore responsible for the extracellular lipase activity of K. marxianus.

Molecular events associated with photoconidiation of Trichoderma are regulated by the BLR-1 and BLR-2 protein complex, where the first plays an essential role as sensor, and both function as a transcriptional factor. Null mutant strains of blr genes in T. atroviride are unable to respond to light stimulation and are then considered blind mutants. Limited concentration of essential nutrients in the media is a condition that triggers conidiation in T. atroviride. In the present study we show the influence of limited concentration of inorganic phosphate (Pi) in the media on photoconidiation in T. atroviride and two blr null mutants. All strains tested showed the development of conidial structures when low levels of Pi (0.1 mM) were present in the absence of light. The data showed that sensing environmental cues such as phosphate limitation is independent of BLR proteins pathway.

Los eventos moleculares asociados a la conidiación inducida por luz en Trichoderma están regulados por el complejo formado por las proteínas BLR-1 y BLR-2, donde la primera actúa como fotorreceptor y ambas tienen actividad como factor de transcripción. Las cepas mutantes nulas en los genes blr de T. atroviride pierden la capacidad de responder al estímulo luminoso y son consideradas "mutantes ciegas". La limitación de algunos nutrientes esenciales también desencadenan la conidiación en T. atroviride. La influencia de bajas concentraciones de fosfato inorgánico (Pi) en el medio de cultivo sobre la fotoconidiación de la cepa silvestre y las mutantes blr de T. atroviride fue probada. Todas las cepas utilizadas mostraron el desarrollo de conidias bajo concentraciones limitantes de Pi (hasta 0.1 mM) en ausencia de la luz. Los resultados indican que la limitación de Pi es un factor desencadenante del proceso de conidiación a través de una vía independiente a la mediada por las proteínas BLR.