Microbiology

Microbiology (Hindi: सूक्ष्मजैविकी or सूक्ष्मजीवविज्ञान) is the scientific exploration of microorganisms. These microorganisms can be unicellular (single-celled), multicellular (composed of complex cells), or acellular (lacking any cellular structure). The field of microbiology includes various sub-disciplines such as virology, bacteriology, protistology, mycology, immunology, and parasitology.

The microbial world is made up of organisms that are categorized as either prokaryotes or eukaryotes. Eukaryotic microorganisms have membrane-bound organelles and include groups like fungi and protists, while prokaryotic organisms are typically defined by the absence of these organelles, encompassing Bacteria and Archaea. Traditionally, microbiologists used methods such as culturing, staining, and microscopy to isolate and identify microorganisms. However, it has been found that less than 1% of microorganisms in typical environments can be cultured in isolation with existing techniques. With the rise of biotechnology, microbiologists now utilize molecular biology tools for identification, such as DNA sequencing methods—one notable example being the 16S rRNA gene sequence, which is commonly employed for identifying bacteria.

Viruses have been classified in various ways, with some viewing them as very simple microorganisms and others as highly complex molecules. Prions, which are not regarded as microorganisms, have also been studied by virologists, particularly because the clinical effects associated with them were initially thought to result from chronic viral infections. This led virologists on a quest that ultimately revealed the existence of "infectious proteins".

The concept of microorganisms was anticipated centuries before they were actually observed, as noted by the Jains in India and Marcus Terentius Varro in ancient Rome. The first documented observation of microorganisms through a microscope was made by Robert Hooke in 1666 when he examined the fruiting bodies of moulds. However, Jesuit priest Athanasius Kircher is believed to be the first to have seen microbes, having reported his observations in milk and decaying matter in 1658. Antonie van Leeuwenhoek is often referred to as the father of microbiology due to his work in the 1670s, during which he observed and experimented with microscopic life using simple microscopes he designed himself. The field of scientific microbiology advanced significantly in the 19th century, largely thanks to the contributions of Louis Pasteur, while medical microbiology was notably shaped by Robert Koch.