India-based startup String Bio is in the process of raising an additional $10 million (€10.2 million) to develop its methane-based protein replacement, just months after raising $20 million (€20.4 million), co-founder and CEO Ezhil Subbian told IntraFish.

The startup uses a fermentation process that uses microbes to convert methane, a greenhouse gas, into proteins for animal feed sector, including aquaculture. The protein can act as a replacement for fishmeal or soy.

The company, which has had its product tested and approved by aquaculture feed giants BioMar and Skretting, raised $20 million in August in a first close.