Vegetarian designer Stella McCartney is eliminating animal products from her line thanks to a new partnership with Silicon Valley biotech company Bolt Threads—which creates yeast-based vegan silk. McCartney will debut a gold shift dress made entirely of the cruelty-free material at the upcoming design exhibition “Items: Is Fashion Modern?” at the Museum of Modern Arts in New York this October. “When I first started in fashion design, I never thought there would be a day like this, where we would arrive with such an important moment when technology is fused with fashion, one of the most harmful industries to the environment,” the designer said. “For me, I’ve always struggled with the use of silk, and finding Bolt has been a life-changing and career-changing moment for me.” McCartney’s brand is not vegan—she still uses wool—but eliminating silk from her line is a major step in the right direction. Bolt Threads hopes to work with the designer for future collections and develop new, more eco-friendly materials for her designs. Last month, McCartney announced a partnership with materials-recycling organization Parlay for the Oceans and committed to using fibers made from recycled ocean trash to create upcoming shoe and accessories collections.