Which of the following is harmful microorganisms?

Bacteria are classified as harmful microorganisms because some strains can cause diseases and infections in humans, animals, and plants. They can produce toxins and invade host tissues, leading to various health issues ranging from mild infections to severe conditions. For example, pathogenic bacteria such as Streptococcus, Escherichia coli, and Salmonella are known to cause illnesses.

Antibodies are proteins produced by the immune system to identify and neutralize harmful pathogens, including bacteria and viruses, so they do not contribute to harm. Probiotics are beneficial bacteria that help maintain a healthy balance of gut microbiota, supporting digestive health and potentially preventing infections. Antiseptics are substances used to inhibit the growth of microbes on living tissue, preventing infections rather than causing harm. Understanding the role of different microorganisms is crucial for maintaining health and treating diseases effectively.