利用PCS生物反應器最適化生產紫芝胞外多醣與其抗發炎能力之探討

Abstract

Ganoderma formosanum又名紫芝，屬於臺灣特有的靈芝品種，近年來已有研究證實其深層培養液所分離出的胞外多醣體具有免疫調節與抗腫瘤的功效；為提高紫芝胞外多醣體的產量，本篇研究以固定化培養的方式- plastic composite support (PCS) 生物反應器作為量產工具，並以抗發炎能力來評估多醣經量產後的活性影響。經最適化結果發現，SF+在四種 (SF+, SY+, SB+ and SR+) PCS中能最有效促進紫芝生長與胞外多醣體的生產；結合培養基碳源的調整和SF+固定化系統的生產，在兩階段醱酵時紫芝胞外多醣的產量已顯著得到提升 ( p < 0.05 )，且連續式生產的實驗中也觀察到重複利用菌體醱酵的情形可達五次之多，如此也反應了PCS生物反應器比起傳統的懸浮培養具有生產週期短、操作便利以及成本低的優勢。在評估多醣體生物活性的實驗中，我們發現經固定化生產的胞外多醣體清除自由基的半抑制濃度較懸浮培養低，且兩者在相同處理濃度下 (125 μg/mL) 抑制RAW 264.7產生發炎因子nitric oxide ( NO ) 的能力亦沒有顯著差異。從單糖組成和β-1,3-glucan的分析結果我們推測其活性來源可能為靈芝活性研究中報導較多的β-glucan和fucose-enriched polysaccharides。

Ganoderma formosanum also named tzu-chih, is an endemic species of lingzhi in Taiwan. Recently, researchers had proved that an extracellular polysaccharides (EPS) purified from submerged culture of G. formosanum could exert immune-modulating and anti-tumor effects. For the purpose of improving G. formosanum EPS, plastic composite support (PCS) immobilization system was developed, also, anti-inflammatory effect was evaluated after the prodution. Among four PCS (SF+, SY+, SB+ and SR+) in selection stage, SF+ immobilized system showed the highest stimulation of EPS and biofilm formation; further in optimization process, SF+ combined with different carbon sources in immobilization system demonstrated a significant improvement of EPS production ( p < 0.05 ) in bi-stage fermentation. During continuous fermentation, 5 repeated-times as many as that of conventional suspended-cell bioreactors was contributed to a shorter producing time, easy manufacturing process and lower cost in PCS bioreactors. Bioactivity evaluation demonstrated that a lower radical scavenging concentration of immobilized group EPS than that of the L/G group, while the anti-inflammatory assay showed no significant difference on inhibiting nitric oxide ( NO ) production with 125 μg/mL EPS treatment in RAW 264.7 cells. Analysis of monosaccharide composition and β-1,3-glucan content depicted that β-glucan and fucose-enriched polysaccharides may contribute to the bioactivity on radical scavenging and anti-inflammation of EPS fermented in suspension and SF+ immobilized system respectively.