熱凝膠多糖產生菌株的復合誘變選育

付雅欣 雷高 方青 高紅亮 楊雪霞

摘要[目的]提高熱凝膠多糖產量和凝膠特性。[方法]采用紫外線和亞硝基胍對土壤桿菌714進行誘變；通過平板-搖瓶篩選方法，得到2株高產菌。[結果]突變菌株0.6-45和0.5-50的熱凝膠多糖粗提得率分別為26.5和26.4 g/L，分別是出發菌株粗提得率（3.8 g/L）的7.0和6.9倍，熱凝膠多糖精提得率分別為19.4和18.0 g/L。凝膠特性分析表明，突變菌株熱凝膠多糖凝膠的破裂強度、破裂位移、彈性、內聚性、恢復性較好，均高于市售樣品，而凝膠強度、硬度、膠著性和咀嚼性低于市售樣品。GPC測定菌株0.6-45和菌株0.5-50產熱凝膠多糖的MW分別為1.57×106和1.27×106 Da。[結論]復合誘變提高了熱凝膠多糖的產量并改善了多糖的凝膠特性。

關鍵詞熱凝膠多糖；紫外誘變；亞硝基胍誘變；高產菌株；凝膠特性

中圖分類號Q93文獻標識碼A文章編號0517-6611（2017）11-0007-04

Abstract[Objective] In order to improve the yield and quality of curdlan.[Method] Agrobacterium sp.714 was mutated by UV and NTG.Two highyield strains were selected by plate spreading and shakingflask fermentation.[Result] The crude yield of curdlan from the strain 0.6-45 and strain 0.5-50 were 26.4 and 26.5 g/L，and were 6.9 and 7.0 times higher than the crude yield of parent strain （3.8 g/L）.The refined yield of curdlan from the strain 0.6-45 and strain 0.5-50 were 19.4 and 18.0 g/L.The characteristics of gel showed that the fracture strength，fracture distance，springiness，cohesiveness and resilience were higher than the sample from market，and the gel strength，hardness，gumminess and chewiness were lower than sample from market.GPC results showed the molecular weights were respectively 1.57×106 and 1.27×106 Da for curdlan from the strain 0.6-45 and 0.5-50.[Conclusion] Combined mutation improves the yield of curdlan and changes the characteristics of gel.

Key wordsCurdlan；UV mutation；NTG mutation；Highyield strain；Gel characteristics

熱凝膠多糖又稱可得然膠，是一種主要由土壤桿菌類微生物產生的胞外β-1，3-葡聚糖[1-3]，因其在加熱條件下可以形成凝膠的獨特性質而得名[4]。熱凝膠多糖最早是在1966年被Harada等[5]發現并開始研究，1996年被美國FDA（Food and Drug Administration）認證安全，可用作食品添加劑[6]。熱凝膠多糖具有獨特的加熱成膠性[7]、良好的持水性[8]、凍融穩定性[9]和安全性[6]等優良特性，近年來研究還發現其具有增強免疫和抗腫瘤的特性[10]，在食品[11-12]、生物醫藥[13-15]等領域具有廣闊的應用前景。

為提高熱凝膠多糖的產量，降低生產成本，國內外研究人員多采用優化發酵工藝提高熱凝膠多糖的產量。West[16]對菌株進行了誘變并結合培養基優化提高多糖的產量；Lee等[17]通過熱凝膠多糖發酵中pH控制策略提高多糖產量；……