Abstract:
Sunflower seed hulls (SSH) are agricultural waste from sunflower seed processing. Biodegradation of lignocellulosic waste using white rot fungi has been known as more harmless method than the chemical treatment, besides solving the environmental problems. The objective of this research was to investigate the effect of temperature, pH, nitrogen source and inducer on lignin degradation and ligninolytic enzyme production by Lentinus polychrous Lev. LP-SW-3 under solid-state fermentation of SSH for 30 days. Temperature at 35-40OC and pH at 5.0-5.5 was the optimum condition for delignification and Iaccase production. The fungus potentially secreted manganese peroxidase (MnP) at 30-4i0°C and pH 4.0-5.5, whereas low production of lignin peroxidase (LiP) was detected in all treatments. ln addition, the high fungal growth was found at 30-40°C and pH 5.0. A study on the addition of two nitrogen sources, including organic nitrogen (peptone and yeast extract) and inorganic nitrogen (KNO3 and (NH,,)2SO,,) during the ferm entation at 35OC was conducted. Adding 3 mM - N KNO3 resulted in the highest lignin loss and Iaccase production, whereas the highest MnP production was found by adding 2% peptone. However, low LiP production was detected in all treatments. The highest fungal growth was detected in the presence of 30 ml\/I-N KNOB. A study on the addition of four inducers, including 1mm MnSO,,, 1 mM CuSOA, 2 mM veratryl alcohol and 2 mM-hydroxybenzaldehyde during the fermentation at 35°C was carried out. The highest lignin loss and Iaccase production were found in the presence of CuSOQ,, while MSO,, and veratryl alcohol enhanced the highest MP and Li production, respectively. Furthermore, the highest fungal growth was detected in the presence of yeratryl alcohol. A study on the addition of 3 mM--NNO3 in combination with 1 ml\/I CuSO4 during the fermentation at 35°C was conducted. This condition resulted in the highest Iaccase production and the fungal growth, compared with other treatments in the research. Consequently, the highest lignin loss was 57.44% after 30 days of fermentation.
WALAILAK UNIVERSITY. CENTER FOR LIBRARY RESOURCES AND EDUCATIONAL MEDIA