Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India.
Appl Biochem Biotechnol. 2012 Jul;167(6):1818-30. doi: 10.1007/s12010-011-9531-5. Epub 2012 Jan 13.
The vast untapped potential of hairy root cultures as a stable source of biologically active chemicals has focused the attention of scientific community toward its commercial exploitation. However, the major bottleneck remains its successful scale-up. Due to branching, the roots form an interlocked matrix that exhibits resistance to oxygen transfer. Thus, present work was undertaken to develop cultivation strategies like optimization of inlet gas composition (in terms of % (v/v) O(2) in air), air-flow rate and addition of oxygen vectors in the medium, to curb the oxygen transfer limitations during hairy root cultivation of Azadirachta indica for in vitro azadirachtin (a biopesticide) production. It was found that increasing the oxygen fraction in the inlet air (in the range, 20-100% (v/v) O(2) in air) increased the azadirachtin productivity by approximately threefold, to a maximum of 4.42 mg/L per day (at 100% (v/v) O(2) in air) with respect to 1.68 mg/L per day in control (air with no oxygen supplementation). Similarly, increasing the air-flow rate (in the range, 0.3-2 vvm) also increased the azadirachtin productivity to a maximum of 1.84 mg/L per day at 0.8 vvm of air-flow rate. On the contrary, addition of oxygen vectors (in the range, 1-4% (v/v); hydrogen peroxide, toluene, Tween 80, kerosene, silicone oil, and n-hexadecane), decreased the azadirachtin productivity with respect to control (1.76 mg/L per day).
发根培养物作为生物活性化学物质的稳定来源，其巨大的未开发潜力引起了科学界的关注，使其朝着商业化开发的方向发展。然而，主要的瓶颈仍然是其成功的扩大规模。由于分枝，根系形成了一个相互交织的基质，表现出对氧传递的阻力。因此，本研究旨在开发培养策略，如优化进气成分（空气中氧气的百分比（v/v））、空气流量和在培养基中添加氧载体，以抑制在印度楝发根培养过程中的氧传递限制，用于体外印苦素（一种生物农药）的生产。研究发现，增加进气中的氧气分数（在 20-100%（v/v）空气中氧气范围内）可使印苦素的生产率提高约三倍，最高可达每天 4.42 毫克/升（在 100%（v/v）空气中氧气），而对照（不补充氧气的空气）为每天 1.68 毫克/升。类似地，增加空气流量（在 0.3-2 vvm 范围内）也可将印苦素的生产率提高到每天 1.84 毫克/升，在空气流量为 0.8 vvm 时达到最大值。相反，添加氧载体（在 1-4%（v/v）范围内；过氧化氢、甲苯、吐温 80、煤油、硅油和十六烷）会降低印苦素的生产率，相对于对照（每天 1.76 毫克/升）。
