Search

CN-121991824-A - Method for preparing lactic acid by pretreatment of lignin-containing biomass through mixed bacteria fermentation broth and collaborative mechanical thread rolling coupled steam explosion

CN121991824ACN 121991824 ACN121991824 ACN 121991824ACN-121991824-A

Abstract

The invention discloses a method for preparing lactic acid by coupling mixed bacteria fermentation liquor and collaborative mechanical thread rolling and steam explosion pretreatment of lignin-rich biomass, which comprises the steps of mixing bacteria liquid consisting of bacillus pumilus, bacillus licheniformis, bacillus stonecrop, pallor pseudomiddle and a liquid culture medium suitable for mixed bacteria growth, fermenting by utilizing the mixed bacteria fermentation liquor, collaborative mechanical thread rolling and steam explosion treatment. The biomass is easier to be permeated by steam after fermentation pretreatment, and the energy of steam explosion can be more fully acted on the material with loose structure, so that the energy consumption intensity is greatly reduced, the generation of harmful byproducts in the high-temperature explosion process of lignocellulose, particularly high-lignin biomass, is effectively reduced, the inhibition of subsequent enzymolysis and fermentation processes is obviously reduced, and the synergistic effect of cost reduction and the synergistic effect of the product quality are realized.

Inventors

  • LIU CHUN
  • GUAN XIUQIONG
  • WEN ZHIGUI
  • ZHENG SHIJIE
  • CHEN JIAXUAN

Assignees

  • 四川轻化工大学

Dates

Publication Date
20260508
Application Date
20260211

Claims (10)

  1. 1. A mixed fermentation broth, comprising: brevibacillus brevis; bacillus licheniformis; Bacillus stonecrop; pseudo-pale bacillus; A liquid medium suitable for mixed bacteria growth; The mixed bacteria fermentation liquid is obtained by mixed culture or respectively fermentation of the Brevibacterium, the Bacillus licheniformis, the Bacillus stonicus and the pseudo-middle pallor bacillus in a liquid culture medium, and the obtained mixed bacteria fermentation liquid is used for pretreatment of preparing lactic acid from lignin-containing biomass.
  2. 2. The mixed fermentation broth of claim 1, wherein the liquid medium is LB liquid medium.
  3. 3. The mixed bacteria fermentation broth of claim 1, which is characterized by being prepared from Brevibacterium brevis, bacillus licheniformis, bacillus stonteus and pseudo-pale bacillus according to the volume ratio (1-3) of the fermentation broth of 1:1:1.
  4. 4. The mixed fermentation broth of claim 1, wherein the OD 600 values of the mixed fermentation broth of bacillus pumilus, bacillus licheniformis, bacillus stonicus, and pallidum pseudomiddle are all 1.2.
  5. 5. The method for preparing lactic acid by utilizing mixed fermentation liquor and mechanical thread rolling coupled steam explosion pretreatment of high lignin biomass is characterized by comprising the following steps: Step 1, preparing and adjusting lignin-containing biomass, the mixed bacteria fermentation liquid of any one of claims 1-4 and Hertz buffer solution, uniformly mixing, performing aerobic fermentation, performing solid-liquid separation after fermentation, and respectively collecting a solid part and a liquid part; step 2, washing the solid separated in the step 1 to obtain biomass with characteristics A; Step 3, mechanically thread rolling the biomass with the characteristic A to obtain biomass with the characteristic B; Step 4, adding deionized water into the biomass with the characteristic B to adjust the initial water content, performing steam explosion treatment, collecting residues after the steam explosion is finished, drying to obtain pretreated biomass, and crushing the pretreated biomass; Step 5, placing cellulase in a weak acid buffer solution, and then placing the crushed pretreated biomass in an enzyme-containing buffer solution for enzymolysis to obtain an enzymolysis matrix; And 6, inoculating the enzymolysis matrix with the bacillus coagulans liquid activated by mMRS culture medium, stirring, adding NaHCO 3 to adjust the pH value to 5.5-6.5, and fermenting until the lactic acid concentration in the supernatant is not increased significantly.
  6. 6. The method for preparing lactic acid by coupling steam explosion pretreatment of high lignin-containing biomass by utilizing mixed bacterial fermentation broth and mechanical thread rolling according to claim 5, wherein in the step 1, the volume ratio of the high lignin-containing biomass to the mixed bacterial fermentation broth to the Hertz buffer is 1 (0.1-0.5): 2.
  7. 7. The method for preparing lactic acid by coupling steam explosion pretreatment of high lignin-containing biomass by utilizing mixed fermentation broth and mechanical thread rolling according to claim 5 or 6, wherein in the step 1, the high lignin-containing biomass, the mixed fermentation broth and the hercyn buffer are proportionally prepared, and then the fermentation concentration is adjusted to 15-35%, and the pH value is adjusted to 7.
  8. 8. The method for preparing lactic acid by coupling steam explosion pretreatment of high lignin biomass by utilizing mixed fermentation broth and mechanical thread rolling according to claim 5, wherein in the step 1, the specific process of aerobic fermentation comprises the following steps: And placing the fermentation raw material in an aerobic fermentation tank, wherein the height of the material is more than 1/2, the temperature is 37 ℃ and is kept for 3-10 days, and in the process, continuous ventilation and stirring are kept, the ventilation amount is 1.0 vvm, and the rotation speed is 200 rpm.
  9. 9. The method for preparing lactic acid by utilizing the mixed fermentation broth to cooperate with mechanical thread rolling coupled steam explosion to pretreat high lignin-containing biomass according to claim 5, wherein in the step 5, the acidic buffer solution is acetic acid-sodium acetate buffer solution.
  10. 10. The method for preparing lactic acid by utilizing mixed fermentation broth to cooperate with mechanical thread rolling to couple with steam explosion pretreatment of biomass high in lignin content, which is characterized in that in the step 6, the inoculation amount of the fermentation broth is 5-15%.

Description

Method for preparing lactic acid by pretreatment of lignin-containing biomass through mixed bacteria fermentation broth and collaborative mechanical thread rolling coupled steam explosion Technical Field The invention relates to the technical field of biochemical engineering, in particular to a method for preparing lactic acid by utilizing mixed fermentation liquor and cooperating with mechanical thread rolling to couple steam explosion pretreatment of biomass with high lignin content. Background Lactic acid is a natural organic acid, is the most cost-competitive bio-plastic monomer, and its polymer polylactic acid is a biodegradable high-molecular material, and can be used for packaging, fiber fabric, agricultural film and 3D printing, etc., and its market prospect is extensive. With the promotion of plastic limiting and the expansion of the consumer market, the expected biodegradable plastic substitution space can reach more than ten millions of tons, and the downstream consumer demand is upgraded, so that the lactic acid demand is driven to rapidly increase. And the straw raw material is used for replacing grains to produce the lactic acid, so that the cost can be further reduced, and the development sustainability of the polylactic acid is enhanced. Currently, enzymatic saccharification is still one of the key steps in the fermentative conversion of lignocellulose to lactic acid. However, the degradation-resistant barrier of lignocellulose is resistant to enzymatic hydrolysis and suitable pretreatment methods are generally required to enhance the hydrolysis effect. The steam explosion method is one of pretreatment methods for effectively improving enzymolysis effect at present because no chemical is used, the treatment time is short, compared with other methods, the steam explosion method permeates a lignin-carbohydrate composite structure of lignocellulose through high-pressure steam, instant pressure release causes material explosion, the barrier effect of lignin is destroyed, the crystallinity of cellulose is reduced, the void ratio of the material is increased, the enzymolysis effect is improved by improving accessibility of enzyme to the cellulose, but the method has high energy consumption, and substances with inhibition effect on activity of cellulose and subsequent fermentation microorganisms, such as furfural, acetic acid, phenolic compounds and the like can be produced. In addition, when the study object is biomass with high lignin content, such as cotton stalk, wood, etc., the blocking effect of lignin (rearrangement and redeposition of lignin) may be aggravated, and more ordered cellulose crystal structure (increased crystallinity of cellulose) is formed, which further affects the efficiency of subsequent enzymolysis and fermentation processes, and further limits the application of steam explosion pretreatment technology. Disclosure of Invention The invention provides a mixed fermentation liquid and a method for preparing lactic acid by coupling steam explosion pretreatment of high lignin-containing biomass by cooperating with mechanical thread rolling, and aims to endow the high lignin-containing biomass raw material with excellent components and structural characteristics by utilizing the novel mixed fermentation liquid and the synergistic effect among mixed fermentation, thread rolling and steam explosion, thereby effectively improving enzymolysis saccharification efficiency benefit, reducing subsequent fermentation inhibition phenomenon and simultaneously reducing energy consumption of the traditional thread rolling and steam explosion process. In view of the foregoing problems of the prior art, according to one aspect of the disclosure, the present invention adopts the following technical solutions: A mixed fermentation broth, comprising: brevibacillus brevis; bacillus licheniformis; Bacillus stonecrop; pseudo-pale bacillus; A liquid medium suitable for mixed bacteria growth; The mixed bacteria fermentation liquid is obtained by mixed culture or respectively fermentation of the Brevibacterium, the Bacillus licheniformis, the Bacillus stonicus and the pseudo-middle pallor bacillus in a liquid culture medium, and the obtained mixed bacteria fermentation liquid is used for pretreatment of preparing lactic acid from lignin-containing biomass. In order to better realize the invention, the further technical scheme is as follows: further, the liquid culture medium is LB liquid culture medium. Further, the microbial strain is prepared from Brevibacillus brevis, bacillus licheniformis, bacillus stonecrop and pallor pseudopallor according to the volume ratio of fermentation liquor (1-3): 1:1:1. Further, the OD 600 values of the Brevibacterium, bacillus licheniformis, bacillus stonteus, and Ochrobactrum pseudomiddle fermentation broths used for the respective post-fermentation mixtures were all 1.2. The invention also provides a method for preparing lactic acid by utilizing mixed fermentation liqu