Bacteria are prokaryotic organisms and fungi are eukaryotic organisms.  Although both have similar cell plasma membranes, differences exist in the types and location of DNA; ribosomes and ribosomal RNA and cell wall structure.  Bacteria are unicellular whereas fungi are unicellular or multicellular.  

The species concept is problematic for bacteria.  As well as using 16S ribosomal RNA gene sequences, bacteria are often grouped according to their morphological, biochemical, antigenic, and growth characteristics.   

Bacteria and fungi have biotechnological uses.  Biotechnology is the industrial use of living organisms to produce food, medicinal drugs or other products, aims to improve agriculture, food production, food science, medicine and industry by improving the production of primary and secondary metabolites.   

The production of primary and secondary metabolites requires understanding of the microbial growth curve and selection of the appropriate means (batch culture, fed batch culture or continuous culture) of culturing organisms. 

Cells are cultured within media which provide nitrogen, carbon, energy and specific growth factors.   The practice of avoiding contamination of cultures is known as aseptic technique. 

Pathogenic micro-organisms, including bacteria, viruses and fungi, cause infectious diseases. Pathogenic bacteria are invasive and / or produce toxins (endotoxins and exotoxins).  Viruses are obligate intracellular parasites which divert the cell’s normal activity.  Fungi cause disease through mycotoxicosis and mycoses.    

Disease prevention can be achieved through interventions at primary, secondary and tertiary levels.  Primary prevention aims to prevent disease before it ever occurs.  Secondary prevention aims to reduce the impact of a disease that has already occurred.  Tertiary prevention aims to soften the impact of an ongoing illness or injury that has lasting effects. 

The human body has physical defences against disease; these include physical barriers, mechanical actions and the microbiome. There are also cellular defences against disease; these are carried out by leucocytes and may be non-specific or specific. 

Non-specific responses, which are also known as innate responses, rely on the detection of conserved features of pathogens. Specific responses, which are also called adaptive immunity, rely on the detection of specific antigens. 

Macrophages, neutrophils and Natural Killer (NK) cells are all involved in non-specific responses. Dendritic cells, B cells and T cells are involved in specific responses.

The detection of a specific antigen triggers a cascade of responses (antigen presentation, activation by interleukins, clonal selection, clonal expansion) that result in antibody production.  Antibodies are globular glycoproteins with a complex 3D structure.  They bind to antigens and inactivate them through neutralisation, agglutination, precipitation and activation of the complement system.   

Immunity to disease may be active or passive, natural or artificial.  Active immunity takes time to develop but provides long term immunity whereas passive immunity provides immediate protection against disease but is relatively short term.