Question

what are harmful and useful bacteria

Answer 1

»» Following are the useful bacteria :
1. Lactobacillus/Döderlein's bacillus
2. Bifidobacterium
3. Escherichia coli (E. coli)
4. Streptomyces
5. Rhizobium
6.Cyanobacteria/Cyanophyta
»» Following are the harmful bacteria :
1. Mycobacteria
2. Clostridium tetani
3. Yersinia pestis
4. Helicobacter pylori
5. Bacillus anthracis

Answer 2

they are grouped into various groups like bacteria fungi ,algae, Protozoa and Virus. many of these organisms are useful to human and nature while some are harmful and even cause diseases . Harmful effects of microorganisms: Bacteria:causes various disease such as typhoid, diarrhea and cholera.