Natural rubber biodegradation by Alternaria alternata and Penicillium chrysogenum isolates
2020
Mollea, Chiara | Bosco, Francesca
In the present work, the biodegradation of natural rubber by means of three filamentous fungi, two Alternaria alternata strains (ANR and BNR) and Penicillium chrysogenum, is reported. The biodegradation process has been optimized in Erlenmeyer flasks and then scaled-up in Fernbach flasks. The biodegradation was performed in stationary liquid cultures with biomass immobilized on ceramic Berl saddles. In the presence of NR as the only carbon source, the maximum value of enzyme activity (0.242 IU/L) was reached at 41 days of incubation and at the end of incubation time, 65 days, a 2% weight loss of NR was detected. In Fernbach flasks, the maximum peroxidase activity value was doubled (0.500 IU/L) and reached earlier, after 6 days. In the same incubation time, a better biodegradation performance (4.3%) was obtained. Moreover, the application of a double biodegradation step allowed to obtain higher biodegradation percentage, 6.8%. Among the different tested microorganisms, A. alternata BNR showed the best biodegradation potentiality in terms of enzyme production and NR degradation. On the basis of the results obtained in liquid cultures, A. alternata BNR is currently applied in a lab-scale microcosm study which has to be considered the preliminary step of an in-field biodegradation process.
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