(9) Nutrients mainly permeate the cell membrane in four ways: simple diffusion, auxiliary diffusion, active transport and population translocation.
(1 1) Growth factors can be divided into vitamins, amino acids, purines or pyrimidine bases according to their chemical structures and physiological functions in vivo.
(13) The life activities of microorganisms can also change the pH of the external environment and decompose sugars, fats, etc. And reduce the pH value; Protein, urea and so on. It is decomposed and the pH value increases.
(14) Thermophilic microorganisms can be divided into mesophilic microorganisms and mesophilic microorganisms.
(16) The lower the temperature, the slower the food spoilage. Only when the food temperature is below-10 degrees Celsius will the growth of microorganisms stop.
(17) Different physiological and biochemical processes of microorganisms have different optimum temperatures.
In (18) hypertonic solution, cells lose water easily, while in hypotonic solution, cells absorb water easily.
(19) generation time should be calculated in the logarithmic phase of bacterial growth.
Two. Definition of terms:
(1) Microbial nutrition: The process of obtaining and utilizing nutrients by microorganisms is called nutrition.
(2) Mono-salt toxicity: Many trace elements are heavy metals, and excessive amounts of trace elements will have toxic effects on the normal metabolism of the body, while excessive amounts of single trace elements will have greater toxic effects, which is called mono-salt toxicity.
(3) Photoautotrophic microorganisms: light is used as energy and can grow normally without any organic matter.
(4) Photoenergy heterotrophic microorganisms: light is used as energy, but growth requires certain organic nutrition.
(5) Chemotactic autotrophic microorganism: It obtains energy by oxidizing organic matter, and its growth does not depend on organic nutrients.
(6) Chemotactic heterotrophic microorganisms: they obtain energy by oxidizing organic matter, and their growth depends on organic nutrients.
(7) Culture medium: it is an artificially prepared nutrient matrix suitable for the growth and reproduction of microorganisms or the production of metabolites.
(8) C/N ratio: refers to the ratio of carbon to nitrogen in the culture medium, and sometimes refers to the ratio of reducing sugar to crude protein in the culture medium.
(9) Selection of culture medium: The culture medium prepared according to the special nutritional requirements of a certain microorganism or a certain type of microorganism or different sensitivities to a certain chemical substance can inhibit the growth of unwanted microorganisms and select the required microorganisms.
(10) Identification medium: A special chemical substance is added to the medium, so that it can have a specific chemical reaction with a metabolite produced after the growth of microorganisms, thus causing obvious characteristic changes.
(1 1) Microorganisms grow under suitable environmental conditions. Microorganisms constantly absorb nutrients and metabolize according to their own metabolic patterns. If assimilation is greater than alienation, the total amount of cell protoplasm increases and the cell volume increases, which is called microbial growth.
(12) bacterial growth curve: Inoculate bacteria in quantitative liquid culture medium, periodically sample and measure the cell number under the condition of stable culture conditions, and plot with culture time as abscissa and logarithm of bacterial number as ordinate to obtain a curve reflecting the change law of bacterial number during the whole culture period.
(13) Generation time: the time required for a single cell to complete a division, that is, the time required to increase a generation.
(14) Batch culture: Microorganisms are cultured in a certain volume of culture medium for a period of time, and finally harvested at one time, which is called batch culture.
(15) Constant turbidity continuous culture: A continuous culture mode that continuously adjusts the inflow and outflow speed of fresh culture medium through the control of photoelectric system in the continuous culture device, so as to keep the turbidity of cell culture constant and continuously grow cells.
(16) Constant continuous culture: A continuous culture mode in which the flow rate of the culture medium is controlled to be constant, so that the nutrients consumed by cell growth can be replenished in time, and the concentration of some nutrients is basically constant, thus keeping the cell growth rate constant and making the growth "continuous".
(17) Synchronous growth: A growth mode in which cell growth is controlled by laboratory technology, so that the population cells are in the same growth stage and all cells divide at the same time.
(18) inhibition: A biological phenomenon in which the growth of microorganisms stops under the action of a sublethal dose factor, but can be resumed after the factor is removed.
(19) Preservation: Measures to prevent or inhibit the growth and reproduction of microorganisms under the action of certain chemical substances or physical factors, so as to prevent food spoilage or mildew of other substances.
(20) Disinfection: measures to kill or inactivate all pathogenic microorganisms through certain methods, so as to achieve the purpose of preventing the spread of infectious diseases.
(2 1) Sterilization: A measure to make all microorganisms inside and outside an object permanently lose their ability to grow and reproduce (including the most heat-resistant spores) by using strong physical and chemical factors.
(22) Synchronous culture: A culture method in which cultured microorganisms are in a relatively consistent state (growing and dividing at the same time) and grow and develop at the same stage.
Three. Short answer questions:
(1) What are the similarities and differences between the four modes of transporting nutrients: simple diffusion, auxiliary diffusion, active transportation and group translocation?
Simple diffusion: diffusion from high concentration to low concentration,
Facilitated diffusion: it needs a carrier, has high specificity, does not consume energy, cannot be transported against concentration, and the rate concentration difference is in direct proportion.
Active transportation: carrier is needed, with high specificity, energy consumption, reversible concentration transportation, and speed has nothing to do with concentration difference.
Group transformation: carrier, specificity, energy consumption and reversible concentration transport are needed, but the solute changes before and after transport.
(2) What nutrients do microorganisms need? What are their main physiological functions?
Carbon source: constitutes the cytoplasm and provides energy for the body to complete the whole physiological activities.
Nitrogen source: available nitrogen source: beneficial to biological growth; Slow-acting nitrogen source: beneficial to the formation of metabolites
Energy: It can provide energy source for microbial life activities.
Inorganic salts: participate in the synthesis of enzymes in microorganisms; As an activator of enzymes; Control the redox potential of cells and maintain the osmotic pressure balance of cells; As an energy source for the growth of some microorganisms.
Growth factor: an organic compound that cannot be synthesized by itself or is not fully synthesized, but is necessary for growth.
Water: 1. Water is an important part of microbial cells, accounting for about 90% of the total living cells; It is an important factor to maintain the normal morphology of cells.
2. A series of physiological and biochemical reactions in the body are inseparable from water;
3. Both the absorption of nutrients and the secretion of metabolites are completed by water;
4. Because of its high specific heat, water is a good conductor of heat, which can effectively control the change of intracellular temperature.
(4) Try to describe the basis for dividing the nutritional types of microorganisms.
An autotrophic organism that can grow on simple inorganic substances.
One is that complex organic matter needs to be used as nutrition when growing: alien organisms.
(5) The growth curve of bacterial pure culture is divided into several periods, and what are the characteristics of each period?
Stagnation: slow division and active metabolism.
Logarithmic phase: vigorous metabolism, rapid growth and stable generation.
Stable phase: the number of newly propagated cells is equal to the number of dead cells, and metabolites begin to accumulate.
Decline: The number of dying cells exceeds the number of newborn cells.
(6) 6) What is the mechanism of pH affecting microbial growth?
PH affects the absorption of nutrients by affecting the permeability of plasma membrane, the stability of membrane structure and the solubility or ionization of substances, thus affecting the growth rate of microorganisms.