LAUSR

Abstract Pine (Pinus ssp.) needle biomass (PNB) was pyrolyzed at 400 °C for 3 h and then subjected to hydrothermal treatment at the same temperature for 10 min, with and without the addition of potassium chloride (KCl). The suspensions of the materials treated hydrothermally were submitted to ultrasound for 5, 10, 20, 30 and 60 min. Diffuse reflectance UV–Vis (DRUV) spectroscopy results for the materials with variations in sonication times were obtained and the band gap energy (E) was calculated. A culture medium containing Saccharomyces cerevisiae was monitored during 30 min of exposure to different materials for the calculation of the 10% (IC10), 30% (IC30) and 50% (IC50) inhibitory concentrations. Of the samples that underwent ultrasonic treatment, the material pyrolyzed at 400 °C without the addition of potassium ions (PNB4003H60) presented the greatest inhibition of 10% of the Saccharomyces cerevisiae cultures. Of the materials without the addition of potassium, the material pyrolyzed and sonicated for 10 min (PNB4003H10) showed the best characteristics for use as a support for Saccharomyces cerevisiae organisms.