Cheese is one of the oldest foods made using microbes. Bacteria and fungi are added to milk to give each cheese its special texture, taste and flavour. Memory hook: "Different microbe, different cheese" - the microbe you use decides the type of cheese you get.
Microbes convert milk into cheese; the specific microbe decides the variety. Swiss cheese uses the bacterium Propionibacterium (CO2 makes holes), while Roquefort uses a Penicillium fungus for flavour.
Your doubts, answered
Is cheese made by bacteria or by fungi?
Both. NCERT says bacteria AND fungi are used to give cheese its texture, taste and flavour. For example, the bacterium Propionibacterium sharmanii makes the large holes in Swiss cheese, while a fungus (Penicillium) ripens Roquefort cheese. So do not memorise cheese as only-bacteria; it depends on the cheese variety.
Which microbe gives Swiss cheese its large holes?
Propionibacterium sharmanii, a bacterium. It produces a large amount of CO2 gas during ripening, and this CO2 forms the big holes (called 'eyes') seen in Swiss cheese. This exact point was asked in NEET 2026. The next concept page covers this in detail.
Which microbe is used in Roquefort cheese?
A specific fungus is grown on Roquefort cheese to ripen it and give a particular flavour. NCERT names the fungus genus as Penicillium. Remember: Roquefort = fungus-ripened, Swiss = bacterium-CO2-holes.
What decides the type or variety of cheese?
The specific microbe used. NCERT states the specificity of texture, flavour and taste comes from the microbes used. Change the microbe and you change the cheese variety. This is a favourite one-line NEET fact.
Are the same microbes used in curd and cheese?
Not the same. Curd is made by lactic acid bacteria (LAB) like Lactobacillus. Cheese uses a wider set of microbes including Propionibacterium and fungi like Penicillium to build texture and flavour. Do not confuse curd microbes with cheese microbes in match-the-column questions.
⚠️ The NEET trap ✗ Cheese is made only by bacteria, just like curd. ✓ Cheese is made by BOTH bacteria and fungi; the specific microbe decides the variety (e.g., Propionibacterium for Swiss holes, Penicillium/fungus for Roquefort). 🧠 NTA loves the word 'fungi' in the cheese line. If you tick only-bacteria, you fall for the trap.
Real NEET questions
2019
Match the following organisms with the products they produce: (a) Lactobacillus (b) Saccharomyces cerevisiae (c) Aspergillus niger (d) Acetobacter aceti with (i) Cheese (ii) Curd (iii) Citric Acid (iv) Bread (v) Acetic acid. Choose the correct option.
A · (a)-(ii), (b)-(iv), (c)-(v), (d)-(iii)
B · (a)-(ii), (b)-(iv), (c)-(iii), (d)-(v) ✓
C · (a)-(iii), (b)-(iv), (c)-(v), (d)-(i)
D · (a)-(ii), (b)-(i), (c)-(iii), (d)-(v)
Solution: Lactobacillus makes curd, Saccharomyces cerevisiae ferments dough for bread, Aspergillus niger makes citric acid, and Acetobacter aceti makes acetic acid. Note that cheese (i) is a distractor here - no listed microbe is matched to it, which tests whether you know cheese uses different microbes like Propionibacterium and fungi.
2025
Which of the following microbes is NOT involved in the preparation of household products? A. Aspergillus niger B. Lactobacillus C. Trichoderma polysporum D. Saccharomyces cerevisiae E. Propionibacterium sharmanii. Choose the correct answer.
A · C and D only
B · C and E only
C · A and B only
D · A and C only ✓
Solution: Lactobacillus (curd), Saccharomyces cerevisiae (bread dough) and Propionibacterium sharmanii (Swiss cheese) ARE household-product microbes. Aspergillus niger (industrial citric acid) and Trichoderma polysporum (cyclosporin A / biocontrol) are NOT household-product microbes. So the answer is A and C only. This confirms Propionibacterium is a household cheese microbe.
Solved Microbes in Human Welfare NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Is cheese making part of household products in NCERT?
Yes. Cheese is listed under microbes in household products, alongside curd and bread. It is described as one of the oldest foods in which microbes were used.
What is the exact NCERT line about cheese?
NCERT says: 'Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.' Learn this line word-for-word for one-mark questions.
Does cheese making produce a gas?
Yes. In Swiss cheese, Propionibacterium sharmanii produces a large amount of CO2 gas, which creates the big holes. CO2 is the main gas produced during cheese making, just like in dough fermentation.
Is Propionibacterium sharmanii a bacterium?
Yes, it is a bacterium. It gives Swiss cheese its large holes by producing CO2. Do not mistake it for a fungus.
