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Notch signaling is a highly conserved pathway existed in multicellular organisms. It plays roles in normal human body development, human cancer initiation, progression and metastasis. The Notch negative regulatory region (NRR) is critical for Notch signaling, and cleavage at the S2 site in the NRR ultimately leads to the activation of Notch signaling. To study the function of human NRR1, we expressed the recombinant human NRR1 (rhNRR1) domain in Escherichia coli. After purification, rhNRR1 was obtained with approximately 94% purity according to SDS-PAGE analysis. Furthermore, the polyclonal anti-rhNRR1 serum raised by immunizing mouse with the purified rhNRR1 was able to reduce the generation of active form of Notch1 intracellular domain in HeLa cells, which implied the raised antibody could recognize and bind the natural conformation of Notch1 NRR. Preparation of rhNRR1 by this way is convenient, time-consuming, and could be used to the preparation of anti-NRR1 therapeutic antibody.

BACKGROUND Moringa leaf is licensed as a new food ingredient and is rich in nutrients. However, due to its high cellulose content, the nutrients are difficult to digest and absorb, which limits the product development and application of Moringa leaf. RESULTS We chose four bacterial strains—Trichoderma reesei CICC 2626, Bacillus pumilus CICC 10440, Bacillus subtilis subsp. CICC 21934, and Bacillus sp. CICC 21942—to ferment with Moringa leaf powder. The results of solid fermentation and liquid fermentation show that the solid-state fermentation using Bacillus pumilus CICC 10440 in a 1:60 ratio with Moringa leaf powder produced the greatest amount of soluble protein (285 mg/g, 2.42 times higher than the control) in 24 h. Using a cellulase activity assay and western blotting, we found that Bacillus pumilus CICC 10440 uses endoglucanase to dissolve the cellulose to release nutrients from the Moringa oleifera leaf. We expanded the fermentation scale of the Moringa oleifera leaf in a 200 l fermenter and produced a 50-kg batch of Moringa oleifera product. CONCLUSION The results showing improvement in the nutrient release of Moringa leaf via microbial fermentation are a promising start and provide a basis for the further product development of Moringa leaf.