Methods and characteristics of obtaining pure culture of microorganisms

1. Dilution of inverted plate

Features: colony separation is more uniform, microbial counting results are relatively accurate. However, the operation is relatively troublesome, heat-sensitive bacteria are sometimes easy to be scalded to death, and strictly aerobic bacteria may also be fixed in the medium growth is affected.

2, coated plate method

Features: the operation is relatively simple, is the more commonly used routine method. However, sometimes due to uneven coating so that some parts of the colonies can not be separated, microbial counting need to pay special attention to the operation of the dilution and coating process, otherwise it is not easy to get accurate results.

3, plate delineation method

Features: simple operation, mostly used for the existing pure culture of the confirmation and separation again.

Application: These three methods can be used for the pure culture of all microorganisms that can form colonies on the surface of solid medium. Moreover, by choosing appropriate selection plates and culture conditions, various microorganisms with specific physiological characteristics can be isolated directly. In combination with anaerobic tank or anaerobic glove box techniques, these three methods can also be used to obtain pure cultures of various anaerobic bacteria.

4, dilution shaking tube method

Features: dilution of the inverted plate method of a variant form, but due to the formation of colonies in the middle of the agar column, observation and picking are relatively difficult.

Application: isolation and observation of strictly anaerobic bacteria in the absence of specialized anaerobic operating equipment.

Two, liquid medium separation

1, dilution method

Features: workload, whether to obtain a pure culture need to rely on statistical speculation.

Application: can not or is not easy to grow on solid media microorganisms for pure culture separation or quantity statistics.

2, enrichment culture

Characteristics: generally can not directly obtain the pure culture of microorganisms, through the enrichment culture to make the original microorganisms that account for a small number of the natural environment greatly increased in the number of microorganisms, and then through the plate method for the isolation of microorganisms and detection of the pure culture of the corresponding microorganisms.

Applications:

(1) Targeted and effective isolation of microorganisms from nature according to their specific growth requirements, as desired;

(2) Isolation and culture of microorganisms designed by scientists to grow in specific environments, even though we don't know what microorganisms can grow in such specific environments.

Three, microscopic operations

Single-cell (spore) picking

Features: the separation process is intuitive, reliable, but the instrumentation and operation technology requirements are high, mostly limited to highly specialized scientific research. The picked microbial single cells or spores need to be cultured in solid or liquid medium to obtain their pure cultures.

Application: to isolate the required microbial cells or spores directly from the sample to obtain its pure culture.