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Microbiological staining analysis: Do you know the color of these bacteria?
Nov 21, 2018

As early as ancient times, humans began to dye fabrics with natural dyes. Since the beginning of the 19th century, synthetic dyes that were cheap and easy to prepare and have a wide chromatographic spectrum have gradually occupied the market. However, some synthetic dyes are banned due to the carcinogenic and sensitizing effects of synthetic precursors or products on the human body.

With the improvement of people's living standards, the concept of healthy and environmentally friendly life has become highly respected. Microorganisms such as bacteria and fungi can stably produce natural pigments by fermentation culture, and the pigment yield is high, which is considered to be one of the main natural dye sources that may replace synthetic dyes at present. In recent years, its application in textile dyeing has gradually gained attention.

In addition, the chromophores of natural dyes produced by microorganisms can be further chemically modified to obtain a broader spectrum; some steroidal microbial dyes have a certain antibacterial effect in addition to bright colors, in fabric functionality. Collation also has potential application value.

The color of bacteria dyed by microorganisms

 

 

 

Purple bacillus: blue and purple

 

There are few microorganisms that produce blue-violet pigments in nature, so natural blue pigments are rare. In 1997, Japan reported a bacterium that produces blue bacillus and purple bacillus, which is derived from contaminated silk: silk is placed in a wet state for several months, and some of it is discolored to blue-violet, from silk. The strain was isolated, and then the pigment was extracted from the cells using an organic solvent tetrahydrofuran. Using this pigment to dye different fabrics, it was found that the pigment has stable performance and good color, and is suitable for dyeing natural fibers such as silk, wool and cotton.

Vibrio: red

 

Some researchers have isolated a strain that produces a bright red dye from the marine sediment, Vibrio, and used it to produce dyeing of wool, nylon, silk and other fabrics. Bacterial culture process: First, a single colony on a basic seawater culture medium (SBRM) agar plate was inoculated into an Erlenmeyer flask containing SBRM liquid medium, and cultured at 30 ° C for 12 h on a shaker at 200 r/min. Subsequently, the culture is expanded, and purification is carried out by filtration, concentration, elution, and the like to obtain lycopene.

The color of the fungus dyed by microorganisms

 

 

 

Aspergillus niger spore powder: color can be adjusted

 

Aspergillus niger is an Aspergillus fungus widely distributed in grains, air and soil, and can be applied as a food coloring agent to soy sauces such as soy sauce and vinegar. Some researchers have creatively used potato dextrose as a liquid medium, and added a certain amount of mixed rare earth to the expanded culture solution of Aspergillus niger spore powder as a dyeing liquid, and then added a sterilized silk fabric for dyeing. Not only the fabric with good leveling property is obtained, the soaping fastness and rubbing fastness of the dyed fabric can reach 4 or 4 to 5, the light fastness reaches 3, and the quality of the spore powder can be controlled by control. Change the color of the fabric.

Monascus: red, purple, orange, yellow

 

Monascus can produce a large amount of natural monascus pigment. The monascus pigment mainly contains six kinds of alcohol-soluble pigments and four water-soluble pigments, mainly red pigment, purple pigment, orange pigment, yellow pigment and the like. Some researchers directly used silkworm to stain silk fabrics. The specific method is: inoculate the cultured Monascus into the culture solution, culture at 28 ~ 30 °C as an expanded culture solution, and then add rare earth as a mordant, The sterilized silk fabric is dyed at a low temperature, and the fastness of the dyed fabric can reach the basic taking requirement.

Fusarium oxysporum: pink purple

 

Some researchers isolated five species of Fusarium oxysporum from the roots of citrus roots infected with root rot, and screened a strain capable of producing pink purple anthraquinone dye and applied it to the dyeing of wool fabrics. It was found that the fabric not only can obtain bright color, but also has high color fastness, and the washing fastness, rubbing fastness, perspiration fastness and light fastness can all meet the performance requirements of textiles.

Cordyceps sinensis: 6 red

 

Cordyceps sinensis BCC1869 is an entomopathogenic fungus that produces six red naphthoquinones. The chemical structure of these naphthoquinones is similar to the commercial red pigments shikonin and levulinin. Studies have shown that naphthoquinones cultured by Cordyceps sinensis have extremely high thermal stability and strong acid and alkali resistance and antibacterial properties. Therefore, Cordyceps BCC1869 as a red dye has a great commercial application for dyeing and finishing textiles. Value, but related reports using it for dyeing have not yet appeared.


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