Antioxidant molecular regulation of fermented wheat bran by White rot fungi in broilers

Abstract

白腐真菌是一種能夠降解木質纖維素的絲狀真菌，其具有分泌纖維酵素的能力，並含有豐富的酚類化合物以及其他次級代謝產物，這些成分可以保護細胞避免受到自由基造成的損傷，同時能提高體內抗氧化之作用。本試驗使用杏鮑菇(Pleurotus eryngii) 用來評估白腐真菌固態發酵麩皮對白肉雞生長性能、抗氧化能力及其基因表現之影響。首先接種10%杏鮑菇太空包於麩皮上，水分含量50%，進行固態發酵12天，測定其有效成分及抗氧化能力之影響，結果顯示，發酵麩皮之總酚含量4.68 mg GAE/g DW，總黃酮含量4.95 mg QE/g DW，粗多醣含量73.4 μg Glucose/g DW，三者皆相較於發酵0天時增加約兩倍 (P<0.001)，而清除DPPH自由基能力亦有隨發酵天數增加而增加 (P<0.05)，同時於雞隻PBMC細胞之抗氧化基因 (HO-1, GST) 表現程度相較於未處理之細胞增加 (P<0.05)，且能使產生ROS的NOX1與ROMO1表現降低，並於MTT lymphocyte proliferation assay分析中有較佳的細胞存活表現。第二部份使用300隻1日齡白肉雞，逢機分配至對照組及分別添加10%麩皮 (WB group) 與10%發酵麩皮 (FWB group) 之飼糧處理。結果顯示，各處理對肉雞生長性狀沒有顯著影響，FWB相較於一般飼糧處理能降低血清中丙二醛 (MDA) 含量 (P<0.05)，同時PBMC細胞之抗氧化基因亦有較高的表現程度 (P<0.05)，且NO產量顯著高於其他對照組 (P<0.05)。綜上所述，經白腐真菌發酵麩皮能調節抗氧化相關之基因，因此具有良好的抗氧化能力，同時亦可調節雞隻免疫能力之功能。

White rot fungi is a group of filamentous fungi able to degrade lignocellulosic biomass. Besides the secretion of cellulose enzyme groups, it contains rich phenolic compounds and other secondary metabolites. These ingredients can protect cells from the damage of free radicals, and improve antioxidant effects. The purpose of this study was to investigate the effects of solid fermented wheat bran by white rot fungi on growth performance, antioxidant ability and the gene expression in broilers. The white rot fungi was used in this study is Pleurotus eryngii. First, the wheat bran was used as a substrate and inoculated with Pleurotus eryngii particles at a ratio of 9:1 in order to conduct solid-state fermentation for 12 day, with 50% moisture at 30℃. Fermented wheat bran contained 4.68 mg gallic acid equivalent/g dry weight (DW), 4.95 mg quercetin equivalent/g DW of total phenolics, 73.4 μg Glucose/g DW of polysaccharide, and the fermented wheat bran was twice higher than the unfermented bran (P<0.001). In addition, the scavenging action of fermented wheat bran was 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical increased significantly by about 1.5 times (P<0.05). In vitro, and under the stimulus of fermented wheat bran, the antioxidant gene expression (HO-1, GST) of chicken peripheral blood mononuclear cells was significantly higher than PBS, ascorbic acid and unfermented wheat bran, by more than 2 times (P<0.05). For genes of NOX1 and ROMO1, the expression of fermented wheat bran was the lowest. The chicken PBMC have better cell alive rate on the MTT lymphocyte proliferation assay. In animal trial, 300 day-old broilers were allocated into three treatments including the basal diet, 10% of wheat bran replaced with corn (WB group), and 10% of fermented wheat bran replaced with corn (FWB group). The results showed that all groups had no significant effect on the growth performance of broilers. The malondialdehyde (MDA) production of the serum in the FWB group was significantly decreased than that of the control group at the age of 21 d and 35 d (P<0.05). The antioxidant gene expression of chicken peripheral blood mononuclear cells was significantly higher than control group. The NO production in FWB was higher than other treatments (P<0.05). In conclusion, fermented wheat bran by white rot fungi could regulate the expression of antioxidant molecular targets, in addition improve their immune function.