(2) Vitamins are necessary for the growth and reproduction of lactic acid bacteria and cannot be synthesized in vivo, so vitamins should be added to the culture medium for cultivating lactic acid bacteria. Lactic acid bacteria are anaerobic microorganisms, and their anaerobic respiration is inhibited when they are aerobic, so it is necessary to provide anaerobic conditions when cultivating anaerobic microorganisms.
(3) (1) In order to obtain uniform single colony, it is necessary to dilute the suspension in gradient and inoculate it on solid medium by dilution coating method. Invert the inoculated culture medium in an incubator to prevent water droplets condensed on the Petri dish cover from falling into the culture medium and causing pollution.
(2) Select a culture medium with proper number of single colonies, add Congo red solution with a certain concentration (Congo red solution turns red after pectin is combined with Congo red), wash off Congo red solution on the surface of the culture medium after a period of time, observe and compare the ratio of colony to hydrolysis (transparent circle) diameter, and screen out strains with high pectinase production.
③ After the obtained strain is cultured in liquid, crude pectinase is obtained from the supernatant of the culture solution. A certain amount of crude pectinase is mixed with a proper amount of pectin solution, and after a certain period of time, the absorbance value is determined to determine the activity of the enzyme. When determining the absorbance value, it is necessary to mix the same amount of inactivated crude pectinase with the same amount of pectin solution as the control of the experiment.
So the answer is:
(1) Application of Plant Tissue Culture Technology
(2) Vitamins are anaerobic
(3)① gradient dilution dilution dilution coating plate inversion ② colony ③ supernatant equal inactivated crude pectinase.