Chen S, Wei D, Hu Z
State Key Laboratory of Bioreactor Engineering, Institute of Biochemistry, East China University of Science and Technology, Shanghai 200237, China.
Wei Sheng Wu Xue Bao. 2001 Jun;41(3):357-62.
Bacillus stearothermophilus was embedded in sodium alginate, chitosan, gelatin respectively and utilized for galacto-oligosaccharides (GOS) production. By comparing with each other in the enzyme recovery, optimal reaction conditions, yields of GOS and mechanical strength of the carriers, the gelatin was selected as better carrier for immobilization. pH, temperature, lactose concentration, lactose conversion and mass transfer resistance of carrier significantly influenced the Yield of GOS. The maximum yield of GOS was 31.2% in a stirred reactor with lactose concentration at 60%. It remained about 88% after 96 h (8 batches) reaction. A packed bed was employed for a continuous reaction at space velocity 0.09 h-1, where GOS yield and reactor productivity was 31.5% and 17.4% respectively. It lost about 20% of its original yield of GOS after 140 h reaction. Products were separated by active charcoal columm. The chemical structure of tetrasaccharide identified by 13C-NMR was beta-D-Gal-(1-->3)-D-Gal-(1-->6)-Dal-(1-->4)-D-Glu.
嗜热栖热放线菌分别包埋于海藻酸钠、壳聚糖、明胶中，用于生产低聚半乳糖（GOS）。通过比较酶回收率、最佳反应条件、GOS产量和载体机械强度，选择明胶作为更好的固定化载体。pH、温度、乳糖浓度、乳糖转化率和载体传质阻力对GOS产量有显著影响。在搅拌反应器中，乳糖浓度为60%时，GOS的最大产量为31.2%。反应96小时（8批次）后，产量仍约为88%。采用填充床在空速0.09 h-1下进行连续反应，此时GOS产量和反应器生产率分别为31.5%和17.4%。反应140小时后，其GOS原始产量损失约20%。产物通过活性炭柱分离。通过13C-NMR鉴定的四糖化学结构为β-D-半乳糖-（1→3）-D-半乳糖-（1→6）-Dal-（1→4）-D-葡萄糖。
