Which organisms are responsible for the conversion of milk into curd?

During the production of bread,it becomes porous due to the release of $CO_2$ by the action of:

Assertion: Yeasts such as $Saccharomyces \text{ } cerevisiae$ are used in the baking industry.
Reason: Carbon dioxide produced during fermentation causes bread dough to rise by thermal expansion.

Which of the following bacteria causes the fermentation of milk and other plant products?

Indian curd is prepared by inoculating milk with:

During the production of bread,the release of $CO_2$ by the action of which organism makes it porous?