Jain perspective in brief:

• Core principle: Ahimsa (non-violence) extends to all living beings, including micro-organisms. Therefore, Jains are mindful of foods that involve harming tiny life forms during their preparation.

• Curd and micro-organisms: Making curd uses bacteria to ferment milk. Some Jains view this as violence to microbes, while others accept curd as a natural, minimally-violent product because it’s a common, everyday dairy item and the process is not done with deliberate harm.

• Practical stance (variant among Digambar and Shwetambar):

- Digambar and Shwetambar traditions often differ in details of purity and what is considered strictly non-violent. Generally, many Jains tolerate or consume dairy products like curd, especially if they are prepared without purposeful killing of microbes beyond what occurs in ordinary fermentation. Some stricter adherents may avoid curd or insist on sources they believe minimize harm (e.g., curd from milk processed in a way they consider less harmful), or avoid fermented foods altogether during strict vows.

• Overall guidance: If you are following a Jain path and are concerned about ahimsa toward micro-life, you can choose curd from a source you trust and that aligns with your practice, or opt for non-fermented dairy or plant-based alternatives during periods of stricter vows.

If you’d like, I can point to specific Jain texts or traditions that discuss ahimsa and food, or explain how different Jain sects view dairy and fermentation in more detail.