【PEP】High School Biology · Selective Compulsory Vol. 3: Kitchen Biology — Exploring the World of Fermentation Engineering

Welcome to the fascinating world ofKitchen BiologyWhen you lift the lid of a kimchi jar or catch the subtle fragrance of fermented rice wine, you are witnessing a millennia-spanning feast of microscopic metabolism.Biotechnologyis not exclusive to the laboratory — it is an integrated discipline that applies life science discoveries to engineer and transform biological components.

Core Concepts & Biochemical Principles

Fermentation: A metabolic process in which microorganisms convert raw materials into desired products under suitable conditions. For example, lactic acid bacteria convert glucose into lactic acid in an anaerobic environment.
Aseptic Technique: This is the "lifeline" of fermentation engineering. The key to obtaining a pure culture lies in preventing contamination, and the core logic revolves arounddisinfection(killing pathogens) andsterilization(killing all microorganisms, including spores).
Basic Stages of Fermentation Engineering: Strain selection,培养基 preparation,moist heat sterilization, inoculation, process control, and product separation & purification.

From "Art" to "Engineering"

Traditional fermentation relied on "experience and feel," whereas modern fermentation engineering achieves precise monitoring. Take the production ofglutamic acid(the main component of MSG), where we must monitor pH and dissolved oxygen in real time inside the fermenter. This is not just a biochemical reaction — it embodies the harmony of "Life, Ecology, and Living," much like how variousfood additiveshave improved our modern lives.

QUESTION 1

Do different fermented foods require the same microorganisms? How do we isolate and culture them?

Yes, they arise naturally through high-temperature induction

No, each requires a selective medium and must be purified under aseptic conditions

No, you can simply expose raw materials to air to isolate them

QUESTION 2

Which of the following statements about the spread plate method is INCORRECT?

A. The number of bacteria in a colony is fixed

B. A single colony on a plate typically originates from one viable cell in the sample

C. The colony count is often lower than the actual number of viable cells

D. Proper dilution is the key to accurate counting

QUESTION 3

In fermentation engineering, what is the fundamental principle behind controlling contamination?

Raising the fermentation temperature

Using antibiotics

Strict disinfection and sterilization

QUESTION 4

Three students used three different setups to make fruit vinegar. Setup C has an air inlet, an exhaust port, and a discharge port. Why is C the most suitable?

Acetic acid bacteria are anaerobic, and Setup C is completely sealed

Acetic acid bacteria are aerobic, and Setup C provides sufficient oxygen

Setup C looks nice and is easy to observe

QUESTION 5

In the fermentation engineering workflow, which step is the key to ensuring product purity?

Medium preparation

moist heat sterilization

Product separation