The most abundant prokaryotes helpu l to humans in making curd from milk and in production of antibiotics are the ones categorised as:

Explanation

1. **Cyanobacteria:** Cyanobacteria, also known as blue-green algae, are photosynthetic prokaryotes that can be found in various environments, including freshwater and marine ecosystems. While they are not directly involved in making curd from milk, they can be important in the production of oxygen and fixing nitrogen in certain ecosystems. They are not typically used in antibiotic production.2. **Archaebacteria:** Archaebacteria, a type of prokaryotic microorganism, are known for their ability to thrive in extreme environments, such as hot springs and deep-sea hydrothermal vents. While they have unique metabolic pathways and are used in biotechnology research, they are not commonly associated with curd production or antibiotic production.3. **Chemosynthetic autotrophs:** Chemosynthetic autotrophs are organisms that use inorganic compounds as an energy source to produce organic compounds. They are not typically involved in making curd from milk. These organisms are more commonly found in extreme environments like hydrothermal vents and are not typically used in antibiotic production.4. **Heterotrophic bacteria:** Heterotrophic bacteria are prokaryotes that obtain energy by consuming organic compounds. In the context of curd production, certain species of heterotrophic bacteria play a crucial role in fermentation, converting lactose in milk to lactic acid, which is essential in curd formation. Additionally, many antibiotics, such as penicillin, are produced by various heterotrophic bacteria.Therefore, the prokaryotes most relevant to curd production and antibiotic production are typically **heterotrophic bacteria**. They are responsible for the fermentation process in curd production and are used in the production of antibiotics.