Introduction:
Antibiotics are substances that are used to treat bacterial infections. They work by either killing the bacteria or inhibiting their growth. Antibiotics are widely used in medicine to treat a variety of infections and have greatly contributed to improving human health and increasing life expectancy. They are obtained from various sources, but the majority of antibiotics are derived from bacteria themselves.

Explanation:
Bacteria as the source of antibiotics:
1. Bacteria produce antibiotics as a defense mechanism against other bacteria in their environment. These antibiotics help them compete for resources and survival.
2. Scientists have identified and isolated many different types of bacteria that produce antibiotics. These bacteria are then cultured and the antibiotics are extracted from them.
3. Examples of antibiotics obtained from bacteria include penicillin, streptomycin, tetracycline, and erythromycin.

Other sources of antibiotics:
1. Fungi: Some antibiotics are obtained from fungi. For example, the antibiotic griseofulvin is derived from the fungus Penicillium griseofulvum. Fungi have also provided the source for antibiotics such as amphotericin B and ketoconazole.
2. Angiosperms: Some plants have been found to produce antibiotics. For example, the antibiotic berberine is obtained from the plant Berberis aristata. However, the number of antibiotics derived from angiosperms is relatively small compared to those obtained from bacteria.
3. Viruses: Viruses are not a significant source of antibiotics. Antibiotics are typically used to treat bacterial infections, and viruses require a different type of treatment, such as antiviral medications.

Conclusion:
In conclusion, the majority of antibiotics are obtained from bacteria. Bacteria themselves produce antibiotics as a defense mechanism, and these antibiotics are then isolated and used for medical purposes. While some antibiotics can be derived from other sources such as fungi and angiosperms, their contribution to the overall antibiotic supply is relatively small. Understanding the sources of antibiotics is important for the development of new antibiotics and the effective treatment of bacterial infections.

Types of antibiotics are eubacterial, actinomycetales and fungal and hence the sources are fungi and bacteria....