Engineered Probiotic for Lycopene Production against ROS Stress in Intestinal Epithelial Cells.

is a food-grade chassis for delivery of bioactive molecules to the intestinal mucosa , while its ability to produce lycopene for detoxification of reactive oxidative species (ROS) is not realized yet. Here, NZ9000 was engineered to synthesize lycopene by heterologous expression of a gene cluster in plasmids or chromosomes, yielding the recombinant strains NZ4 and NZ5 with 0.59 and 0.54 mg/L lycopene production, respectively. To reroute the pyruvate flux to lycopene, the main lactate dehydrogenase and α-acetolactate synthase pathways were sequentially disrupted. The resultant strains NZΔldh-1 and NZΔldhΔals-1 increased lycopene accumulation to 0.70 and 0.73 mg/L, respectively, while their biomasses were reduced by 12.42% and the intracellular NADH/NAD ratios increased by 3.05- and 2.10-fold. To increase the biomasses of these engineered strains, aerobic respiration was activated and tuned by the addition of exogenous heme and oxygen. As a result, the engineered strains partly recovered the growth and redox balance, yielding the lycopene levels of 0.91-1.09 mg/L. The engineered strain protected the intestinal epithelial cells NCM460 against HO challenge, with a 30.09% increase of cell survival and a 29.2% decrease of the intracellular ROS level compared with strain NZ9000 treatment. In summary, this work established the use of the engineered probiotic for lycopene production and prospected its potential in the prevention of intestinal oxidative damage.