Influence Of Different Combination Of Lignocellulose Decomposing Strains On Oil Palm Fiber Degradation

In recent years,oil palm has been planted more widely in the coastal provinces in south China,which significantly increased the palm oil production and the farmers' income.However,management of the resulting by-products,such as the empty palm shells and the fiber residues,has become an important problem to be solved.At present,most of the palm fiber is piled up in the plantations and allowed for rot naturally,which lead to serious waste of nutrient resources,environment pollution,and stimulation of plant pathogens and pests reproduction,and finally disturb palm fruit production and sustainable development.Biodegradation is an important strategy for resource of waste lignocellulose material,but single strain could hardly meet requirement.In this study,several lignocellulose decomposing strains were isolated from oil palm fiber;different combinations of newly isolated strain and several other outstanding decomposing strains collected in this laboratory were constructed,and their degradation effects of oil palm fiber were evaluated.The main results obtained were listed as below:1.Composition and physicochemical indexes assessment of oil palm fiber indicated that the concentration of cellulose,hemicellulose,and lignin were 21.55%,26.66%,and 44.29%,respectively,suggesting that degradation by single strain is quite difficult.2.Six bacterial strains and two fungal strains were isolated from the rotted oil palm fiber.Growth tests using oil palm fiber as the sole carbon source and degradation experiments revealed that Aspergillus fumigatus L-1 was the most ideal strain for fiber decomposing,and it was selected out for further combination assays.Other three lignocellulose decomposing strains,including A.fumigatus Z-5,Phanerochaete chrysosporium ACCC30530 and ACCC30553,were also chosen.Liquid fermentation of the four stains using oil palm fiber as the sole carbon source was performed;the activity of cellulase,hemicellulase,ligninase,as well as the degradation rate,were all investigated.Results indicated that two A.fumigatus strains secreted higher activity of xylanase,as the maximum activity of strain Z-5 was 340.23 U/L;while the two P.chrysosporium strains were more dominant in ligninase.At the end of liquid fermentation,the degradation rate of oil palm fiber by strains L-1,Z-5,ACCC30530,and ACCC30553 was 18.04%,21.69%,26.21%,and 25.80%,respectively.3.Different combinations of one A,fumigatus strain(L-1 or Z-5)and one P.chrysosporium strain with different ratios were constructed,and the influence on oil palm fiber degradation was investigated.Results indicated that the optimal combination was A.fumigatus Z-5 mixed with P.chrysosporium ACCC30530 with a ratio of 2:1.The best liquid fermentation condition was temperature of 28?,rotate speed of 170 r/min,inoculation volume of 2-5%,and using powder of oil palm fiber as the material.After fermentation for 13-16 days under this condition,the highest activity of cellulase,hemicellulase,and ligninase could be recovered;also the highest degradation rate of 29.30%could be obtained,which was higher than that of each single strain.4.The strain combination and the fermentation conditions were further verified through the solid fermentation experiment.After fermentation of 25 days,the degradation rate of 11.56%was observed.In conclusion,one outstanding lignocellulose decomposing strain,A.fumigatus L-1,was isolated from oil palm fiber;the combination of A.fumigatus Z-5 mixed with P.chrysosporium ACCC30530 exhibited the highest enzyme activity and degradation rate under liquid fermentation conditions,which was better than that of each single strain;the degradation effects was also investigated under solid fermentation conditions.The results in this study could provide both academic and practical guidelines for resource utilization of oil palm fiber.