Effects of air flow on production of vaccine protein against swine edema disease in transgenic lettuce

Abstract

The transgenic lettuce expressing double repeated Stx2eB (2 × Stx2eB) is considered to be an edible vaccine candidate against swine edema disease. For the efficient vaccine protein production in transgenic lettuce grown in a plant factory, the effects of air flow on vaccine protein production in transgenic lettuce were investigated. Plants were grown hydroponically in a closed-type plant factory for 21 days with four airflow patterns: 1) air flow from the side to leaves at 2.0 m s -1; 2) air flow from the top to the inner developing leaves with flexible transparent tubing at 1.0 m s -1; 3) air flow from the bottom to leaves with transparent tubing at 1.0 m s -1; and 4) no air flow. Our results showed that the total leaf number in air flow from the top and the bottom to leaves was significantly increased compared with that in no air flow. While lettuce growth with inner air flow and bottom air flow was enhanced, tipburn at the developing leaves were eliminated by air flow. 2 × Stx2eB per plant in bottom air flow to leaves was the highest of the four air flow patterns. These results suggest that bottom air flow to the leaves can enhance vaccine protein productivity in transgenic lettuce.