Exploring the Potential of Beneficial Paecilomyces to Improve Plant Growth ^†

Introduction: For sustainable agriculture, an attempt has been made to reduce the use of fertilizers and agrochemicals, replacing them instead with biostimulants as viable alternatives. Biostimulant compounds can be obtained by hydrolysis of proteins derived from plant or animal material. In addition, some microorganisms are used to obtain biostimulants, which can increase crop yields and quality by assisting in the assimilation of nutrients [1,2]. Protein hydrolysates (PH) from microbial cultures represent a particular category of biostimulants, being an abundant protein and amino acid source for new upcycling processes with potential uses in agriculture. In the present paper, we have attempted to highlight the ability of Paecilomyces lilacinus isolate to convert keratin waste into a mixture of sulfur and nitrogen, which can be used to stimulate plant growth and increase crop output [3]. Materials and Methods: Several experiments were carried out; namely, strain characterisation (siderophores production, phosphorus and zinc solubilisation, secreting of hydrolytic enzymes) and the biocontrol capacity of fungal strains against phytopathogens [4]. Qualitative tests were carried out in Petri dishes using solid media with specific compositions. Results: The solubilization capacity of phosphorus and zinc, expressed by our Paecilomyces, refers to the property of transforming insoluble forms of phosphorus and zinc into forms that are accessible to plants. These properties could improve the absorption of phosphate and zinc by plants, helping their growth and development. In addition, Paecilomyces lilacinus had the ability to produce hydrolytic enzymes (cellulase, keratinase, chitinase) responsible for the degradation of pathogen cell walls. Paecilomyces lilacinus exhibited the highest antifungal activity against the Cladosporium sp. isolate (inhibition of 66.31%), followed by Sclerotinia sclerotiorum (inhibition of 50.23%) and Rhizoctonia solani (52.53%). The lowest inhibitory activity was found against Alternaria alternata and Botrytis allii. Conclusions: The present study showed the capacity of Paecilomyces lilacinus to solubilize essential micronutrients to produce hydrolytic enzymes that are involved in the inhibition of pathogens. These characteristics suggest that the strain is a good biostimulating agent and that further investigations in greenhouses and under field conditions are required.