Immobilization of morchella esculenta exract with hydrochar obtained from solid wastes in subcritical water, application to air filter and investigation of antimicrobial propeerties

Filtration technology is one of the most widely used methods to control aerosols and hydrosols. However, microorganisms collected on a filter surface can survive and grow. Microorganisms on the filter surface threaten human health. Antimicrobial agents can be used to prevent this threat. Nowadays, resistance to antibiotics has led to the search for natural antimicrobial sources. In this study, 3 different extracts (acetone, ethanol:water soxhlet, ethanol:water ultrasonic) of M. esculenta mushroom were obtained by 2 different methods (soxhlet and ultrasonic assisted) to obtain a natural antimicrobial agent. The obtained M. esculenta extract (MeE) was combined with almond shell hydrochar (ASH) to be more stable and to increase its antimicrobial activity with a synergistic effect. Almond shell wastes, which cause environmental pollution and are used as solid fuel, were obtained by using the subcritical water (SCS) method and the obtained hydrochar and the extract were immobilized using an ultrasonicator. In the study, the antimicrobial properties of the extracts and hydrochar were investigated. The most effective extract of M. esculenta was acetone extract. M. esculenta acetone extract MIC values 22,6 mg/mL for E. coli, 69,2 mg/mL for E. faecalis, 28,7 mg/mL for S. aureus, 15,8 mg/mL for C. albicans, 13,6 mg for C. parapsilosis /mL, and 41,7 mg/mL for C. tropicalis. The zones of inhibition of the respective extract were 16,74 mm for E. coli, 12,87 mm for E. faecalis, 26,2 mm for S. aureus, 22,22 mm for C. albicans, 12,7 mm for C. parapsilosis and 30,0 mm for C. tropicalis (p < 0,05). The characterization of ASH *MeAE was performed and the antimicrobial activity of ASH*MeAE fixed to the filter was measured using the time-dependent death dynamics method. According to the result of time-dependent inactivation of pathogens exposed to filter-fixed ASH *MeE, the highest logarithmic and percent in 5 minutes was 2,24 KOB/cm2 and 99,33% in Candida parapsilosis, while the highest decrease was observed in C. parapsilosis at the end of the 15th min (1,85 KOB/cm2 , 98,7%). Based on these results, it can be said that the antimicrobial activity of M. esculenta extract is higher against bacteria than fungi. All these results showed that ASH*MeAE fixed on the filter showed antimicrobial properties and could inhibit microorganisms that can survive and even reproduce on filters in daily life.