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Natural strain for producing pullulan and application of natural strain

A technology of pullulan polysaccharides and bacterial strains, applied in the field of microorganisms, can solve the problems of small cells, large glucose repression, and ineffective control of bacterial contamination.

Inactive Publication Date: 2021-03-02
OCEAN UNIV OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the pullulan polysaccharide-producing yeast strains commonly used at present are isolated from plant leaves, soil and sea mud. The cells are yeast-like cells, small cells, thin cell walls, large and few vacuoles in the cells, and most of the chromosomal genes do not appear. Doubling (Sugumaran and Ponnusami, 2017; Liu et al., 2018), which determines that these pullulan polysaccharide-producing yeast strains are not resistant to high osmotic pressure, have a large glucose repression, and cannot be effective in high glucose medium Converting Glucose to Produce High Concentration Pullulan
To reduce the glucose repression, the fed-batch fermentation method mentioned in the CN201710426406 patent has to be used, which increases the complexity of the process, is not convenient for automatic production and cannot effectively control the contamination of miscellaneous bacteria

Method used

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  • Natural strain for producing pullulan and application of natural strain
  • Natural strain for producing pullulan and application of natural strain
  • Natural strain for producing pullulan and application of natural strain

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Embodiment 1: strain screening

[0032] 1. Collection of samples and separation of yeast cells

[0033] When Sophora japonica blooms in May every year in the north, collect 100 grams of honeycombs from all over the country, and quickly put them into sterile centrifuge tubes through aseptic operation. Take it back to the microbiology laboratory quickly, inoculate 1-2 grams of honey into 50.0 mL of liquid medium containing 140.0 g / L glucose and 0.5 g / L chloramphenicol, and culture it at a constant temperature of 28 ° C for 5 days. Dilute the bacterial suspension obtained with sterile physiological saline, and carry out a series of dilutions, and the diluted solution is evenly spread on the solid medium containing 140.0g / L glucose and 0.5g / L chloramphenicol by aseptic operation, at 28 Cultivate at constant temperature for 5 days to obtain various colonies. According to the unique colony morphological characteristics of different strains of Aureobasidium spp., different c...

Embodiment 2

[0036] Example 2: Morphological observation and taxonomic identification of XCC bacterial strains

[0037] The XCC strains were cultured on the above-mentioned YPD medium plate and potato juice+10.0g / L glucose+20.0g / L agar (PDA) plate (28°C) for 4 days. Use an ordinary camera to take pictures of the colony morphology, observe the cultured yeast cells with a 100× oil lens of a fluorescent microscope, and take pictures. It is found that most of the cells of the XCC strain cultured on the YPD plate are typical yeast budding cells, that is, there are transparent arthrospores . Most of the cells cultured on the PDA plate were chryspores with and without melanin, and the chryspores without melanin could divide by forming diaphragms.

[0038] When cultured in the medium for producing pullulan, most of the cells of the XCC strain are thick-walled spores that do not contain melanin, and the production of pullulan is very high at this time, so it is the thick-walled spores that do not ...

Embodiment 3

[0039] Example 3: Preparation of XCC strain cell ultrathin sections and transmission electron microscope observation

[0040] In order to compare with the currently widely used pullulan-producing Aureobasidium melanogenum P16 strain (hereinafter referred to as P16 strain) cells, the above-mentioned pullulan-producing fermentation medium was used to cultivate XCC strain and P16 strain at the same time. The cultured cells were prefixed with 3.0% glutaraldehyde (prepared with 0.1M phosphate buffer) for 3 hours, and then fixed with 1.0% osmic acid for 2 hours. The fixed cells were dehydrated with ethanol, and the dehydrated cells were embedded in Epon-812 resin. Ultrathin sections of embedded yeast cells were prepared with an ultramicrotome (LKB-NOVA, Japan) and stained with lead acetate and uranyl acetate. The prepared ultrathin sections of yeast were observed and photographed with a transmission electron microscope (H-7000, Hitachi, Japan). It was found that most of the cells ...

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Abstract

The invention relates to the technical field of microorganisms, and discloses a natural strain for producing pullulan and application of the natural strain. The preservation number of the natural strain disclosed by the invention is CCTCC NO: M 2020207. According to the invention, the preserved Aureobasidium sp. XCC strain is separated from fresh natural honey collected in various regions of China, 140.0 g / L of glucose can be converted in the fermentation process to generate 110.2+ / -1.2 g / L of pullulan, the conversion rate of the glucose reaches 80% or above, the production intensity reaches 0.80 g / L / h, In natural saccharomycetes of the Aureobasidium spp. at present, the strain is a strain with the highest yield of pulullan biosynthesized by fermenting glucose. Meanwhile, the molecular weight of the synthesized pullulan is as high as 3 x 10<5> and is higher than the average molecular weight of commercialized pullulan sold in the market at present.

Description

technical field [0001] The invention relates to the technical field of microorganisms, in particular to a natural bacterial strain for producing pullulan and its application. Background technique [0002] The Chinese of Aureobasidium spp. is Aureobasidium spp., which belongs to the semi-ascomycete fungus, a dimorphic yeast-like fungus with yeast-like cells and filaments, which can produce pullulan and other products. Pullulan is mainly a linear extracellular glucan produced by different strains of Aureobasidium spp. It is structurally composed of repeated maltotriose units connected by α-(1→6) glycosidic bonds; this This connection makes pullulan have good structural flexibility, water solubility, adhesion, oxygen impermeability, film-forming property and easy degradation. Therefore, it has been widely used in food, cosmetics, biomedicine and other fields and has attracted much attention. my country approved pullulan as a new food additive in 2006. In Japan, pullulan is c...

Claims

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Application Information

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IPC IPC(8): C12N1/14C12P19/10C12R1/645
CPCC12P19/10
Inventor 池哲池振明刘光磊
Owner OCEAN UNIV OF CHINA
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