The most abundant prokaryotes helpful to humans in making curd from milk and in production of antibiotics are the ones categorised as (a) cyanobacteria (b) archaebacteria (c) chemosynthetic autotrophs (d) heterotrophic bacteria
Option D Maximum number of antibiotics are produced by mycelial bacteria known as actinomycetes and most of the actinomycetes are saprotrophic (heterotrophic). Lactic acid bacteria that are used in preparation of curd are also heterotrophic ones.
