The growth of bacteria, the period when the number of live bacteria grows extremely fast is .

Myth 1: Put down the toilet lid when flushing the toilet. （√

According to a study by the University of Arizona in the United States, flushing the toilet without lowering the lid creates a spray effect that spreads germs throughout the room — sometimes to a square meter — and can hang in the air for up to two hours.

Claim 2: Public toilet doorknobs are full of bacteria. （×

When people touch the doorknobs of public toilets, they usually feel nauseous and rush to wash their hands clean. But Powell, a microbiologist at the University of Melbourne in Australia, said: "Bacteria need a relatively humid environment to grow, and doorknobs are relatively dry, so most bacteria struggle to survive for a long time."

Claim 3: Toilet cushions have a lot of bacteria. （×

Generally speaking, toilet cushions are indeed a breeding ground for some bacteria, but research from the University of Arizona shows that toilet cushions are the least bacterially contaminated part of the home environment, behind bathroom floors and cutting boards.

Claim 4: Because there is often running water and detergent, the kitchen sink is very clean. （×

If you think that the water in the dishwashing dish keeps the kitchen sink free of bacteria, you're wrong. "Pools have all the facilities for bacteria to grow," Mr. Powell said, "and they're generally damp and used to clean leftovers." ”

After each dishwashing, wash the kitchen sink with clean hot water. Powell cautioned that it is especially important to rinse with clean hot water when washing pet plates and other utensils in the kitchen sink, "There have been people who have washed glass fish tanks in the kitchen sink, and as a result, a family has been infected with Salmonella. ”

Claim 5: There are many bacteria on the rag. （√

Researchers at the University of Arizona have found that kitchen rags are one of the most bacteria-contaminated areas in the home. "The rag is damp and somewhat warm, which is good for bacterial growth. "While many bacteria usually don't cause much of a problem, pathogens like staphylococcus that can cause food poisoning are likely to survive on the rag."

Therefore, the rag can be disinfected with a microwave or completely sun-dried, but the best way is to change the rag every week.

Claim 6: Your desk is a sterile place for dining. （×

Researchers from the University of Arizona examined the bacterial distribution of office supplies and found that handsets, computers, keyboards and mice were the top four office supplies with the highest number of bacteria.

But Barton also points out that because the surface of these office supplies is dry, they are mostly filled with germs that don't make people sick.

Myth 7: Antimicrobial agents are good for dealing with bacteria**. （×

Antimicrobials are effective to some extent, but the bacteria need to come into contact with the disinfectant for a period of time before they die. Barton said. In addition, Powell also said that excessive use of antimicrobials may also lead to the emergence of bacteria that can resist antibiotics. Satisfied.

This is a biology problem, take a bacterium to you as an example, one becomes two, and then two becomes six, and so on.

Answer]: The growth curve of B bacteria is divided into 4 periods: Retardation period:

It is the adaptation stage after the early ascending bacteria enter the new environment; Logarithmic phase: the logarithm of the number of viable bacteria increased in a straight line, and the morphology, staining and physiological activity of bacteria in this stage were more typical, and they were more sensitive to the effects of external environmental factors. Stable period: the number of bacterial deaths gradually increases, and the number of bacterial reproduction and death is roughly balanced. Decay Period:

The number of dead bacteria exceeds the number of viable bacteria.

Answer]: B test point: the way and speed of bacterial growth and reproduction.

Analysis: The growth curve of bacteria is divided into four phases: retardation phase, logarithmic phase, stable phase, and decay phase.

The sluggish phase is the adaptation stage of bacteria after entering a new environment; In the logarithmic phase, the bacteria in the logarithmic phase increased geometrically, and the number of viable bacteria increased in a straight line on the growth curve, and the growth was extremely fast. The number of bacterial reproduction and death in the stable period was roughly balanced. In the decay period, the reproduction of bacteria gradually slows down, and the death gradually increases, and the number of dead bacteria exceeds the number of viable bacteria.

It is the "logarithmic growth period".

Generally, the typical curves of microbial growth are roughly divided into four periods: lag period, logarithmic phase, stable phase and decay period.

The logarithmic growth phase, also known as the exponential growth phase, refers to the increase in the number of cells in a geometric progression after the adjustment of the delay period, that is, by 20 21 22 · 2n growth for a period of time.

When microorganisms enter a new growth environment, it takes a period of time to adapt, during which the number of microorganisms increases less, but there are not many deaths. This period is called the deferment period or adjustment period.

When the microorganisms adapt to the environment, the temperature and moisture are suitable, the nutrients in the environment are sufficient, and there are no harmful substances, the microorganisms enter a period of rapid growth and reproduction, and their number increases almost exponentially, and the intergenerational time is also very short. This is known as the logarithmic growth phase.

After that, with the extension of the culture time, the consumption of nutrients, the increase of microbial metabolites, the gradual restriction of microbial growth and reproduction, the increase of aging cells, and the increase in the number of deaths, the growth of microorganisms entered a stable period, and finally entered the decline period.

Cloudy growth: Most bacteria.

Precipitate growth: a small number of bacteria arranged in a chain such as streptococcus, Bacillus anthracis.

Bacterial film growth (surface growth): obligate aerobic bacteria such as Bacillus subtilis, Mycobacterium tuberculosis.

and Pseudomonas aeruginosa.

Cloudy growth: Most bacteria bucket several rounds.

Precipitate growth: a small number of bacteria arranged in a chain such as streptococcus and Bacillus anthracis.

Membrane growth (surface growth): obligate aerobes such as Bacillus subtilis, Mycobacterium tuberculosis, and Pseudomonas aeruginosa.