You mean to make natto directly without using Bacillus natto and fresh natto as primers? If this is difficult to achieve in the city, it is that the environment is too bad. If I am in the country, I think if I put it in the air to dry, I should be able to catch bacteria. Or get some straw, blanch it in water at about 70 degrees, then mix it with steamed beans and ferment it at 40 degrees for 24 hours. See if you can arrive on time. Shenyang Shouxing Biotechnology Co., Ltd. specializes in producing Bacillus natto. Welcome to communicate.