Department of Chemical Engineerig, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran.
Fisheries Department, Faculty of Marine Sciences, Chabahar Maritime University, Chabahar, Iran.
BMC Biotechnol. 2023 Jan 24;23(1):2. doi: 10.1186/s12896-022-00772-4.
Rhamnolipids are a group of the extracellular microbial surface-active molecules produced by certain Pseudomonas species with various environmental and industrial applications. The goal of the present research was to identify and optimize key process parameters for Pseudomonas aeruginosa PTCC 1074s synthesis of rhamnolipids utilizing soybean meal in solid state fermentation. A fractional factorial design was used to screen the key nutritional and environmental parameters to achieve the high rhamnolipid production. Response surface methodology was used to optimize the levels of four significant factors.
The characterization of biosurfactant by TLC, FT-IR and H-NMR showed the rhamnolipids presence. In the optimum conditions (temperature 34.5 °C, humidity 80%, inoculum size 1.4 mL, and glycerol 5%), the experimental value of rhamnolipid production was 19.68 g/kg dry substrate. The obtained rhamnolipid biosurfactant decreased water's surface tension from 71.8 ± 0.4 to 32.2 ± 0.2 mN/m with a critical micelle concentration of nearly 70 mg/L. Additionally, analysis of the emulsification activity revealed that the generated biosurfactant was stable throughout a broad pH, temperature, and NaCl concentration range.
The current study confirmed the considerable potential of agro-industrial residues in the production of rhamnolipid and enhanced the production yield by screening and optimizing the significant process parameters.
鼠李糖脂是一类由某些假单胞菌属产生的胞外微生物表面活性分子，具有多种环境和工业应用。本研究的目的是利用固态发酵法从大豆粉中筛选出关键的过程参数，以鉴定和优化铜绿假单胞菌 PTCC 10744 合成鼠李糖脂的方法。采用部分因子设计筛选关键营养和环境参数，以实现高鼠李糖脂产量。利用响应面法优化四个显著因素的水平。
通过 TLC、FT-IR 和 H-NMR 对生物表面活性剂进行了特征描述，表明存在鼠李糖脂。在最佳条件（温度 34.5°C、湿度 80%、接种量 1.4 mL 和甘油 5%）下，鼠李糖脂产量的实验值为 19.68 g/kg 干基质。所获得的鼠李糖脂生物表面活性剂可将水的表面张力从 71.8±0.4 mN/m 降低至 32.2±0.2 mN/m，临界胶束浓度接近 70 mg/L。此外，对乳化活性的分析表明，生成的生物表面活性剂在较宽的 pH、温度和 NaCl 浓度范围内均稳定。
本研究证实了农业工业废料在生产鼠李糖脂方面具有巨大的潜力，并通过筛选和优化重要的工艺参数提高了产量。
