Background
The erythromycin is a large-ring lactone antibiotic, mainly comprises 6 components of erythromycin A, erythromycin B, erythromycin C, erythromycin D, erythromycin E, erythromycin F and the like, wherein the antibacterial activity of the erythromycin A is strongest. Erythromycin is usually produced by a microbial fermentation method, and in the fermentation culture process, erythromycin impurity components in fermentation liquor and erythromycin A as a main component are produced simultaneously, and the content of the erythromycin components in the fermentation liquor is different due to different fermentation processes. When the fermentation is abnormal, the content of the erythromycin A component is lower than 70 percent, and the main impurity component erythromycin B, C, D is higher. The traditional extraction process cannot effectively separate impurity components. At present, two main processes are used for extracting erythromycin from fermentation liquor: the process 1 comprises the following steps: microfiltration of fermentation liquor, resin impurity removal of filtrate, nanofiltration, concentration, crystallization and recrystallization. And (2) a process: filtering the fermentation liquor by a plate frame, extracting by a solvent, removing impurities from the extract liquor, and crystallizing the extract liquor.
The traditional erythromycin fermentation liquor filtration uses a microfiltration membrane or a plate frame, the filtration precision is low, filtrate contains a large amount of protein and pigment, resin is required for purification treatment, the process is complex, and the amount of wastewater generated in production is large.
In the traditional extraction method, a solvent is used for extraction, the solvent mainly used is butyl acetate or a mixed solvent containing butyl acetate, when the erythromycin thiocyanate is crystallized, the content of the obtained erythromycin thiocyanate A is below 80%, the content of erythromycin B and C impurities is more than 3.0%, and the total yield in the crystallization process is less than 85%.
CN103044508B discloses a method for extracting crystallized erythromycin thiocyanate from an erythromycin fermentation broth, which comprises the steps of filtering with an ultrafiltration membrane, concentrating the filtrate by nanofiltration, adding erythromycin thiocyanate into the concentrated solution to obtain crude salt, and dissolving the crude salt in a pre-solvent such as amyl acetate or dichloromethane. Or extracting erythromycin in the concentrated solution into a pre-solvent under an alkaline condition, decolorizing with activated carbon, adding acetone into the decolorized solution, and finally adding thiocyanate for crystallization. The patent uses a plurality of solvents, the solvent recovery and separation are difficult, and the solvent phase is decolorized, and the solvent loss is large. Two crystallizations are used, with a large yield loss.
Patent CN105348340A discloses a preparation method of erythromycin thiocyanate, which comprises the steps of dehydrating the extracted light phase by using saturated sodium chloride, decoloring by using activated carbon, adding a thiocyanate solution, salifying with erythromycin, adding a composite solvent, and adjusting pH by using an acetic acid solution to crystallize to obtain the erythromycin thiocyanate. In the patent, activated carbon is used in a solvent, so that the solvent is not suitable for recovery, the solvent loss is large, and the compound solvent is added during salt formation, so that the solvent has more components and is difficult to separate.
CN201610177576 discloses a preparation method of high-purity erythromycin A, which comprises the steps of dissolving erythromycin thiocyanate in two phases composed of an organic solvent and water by adding alkali, taking the organic phase, adding water for washing, separating out erythromycin A alkali in the organic phase, filtering, drying, and recrystallizing the dry powder by using water as a solvent to obtain high-purity erythromycin A. The method comprises the steps of taking erythromycin thiocyanate as raw powder, crystallizing erythromycin A alkali after dissolving, and recrystallizing to obtain erythromycin A.
Disclosure of Invention
Aiming at the technical current situation, the invention provides a method for extracting low-content erythromycin A in fermentation liquor, and the finished product obtained by the method has the advantages that the content of the erythromycin A is more than 80 percent, the content of erythromycin B and C is less than 3 percent, and the content of other impurities meets the pharmacopoeia standard. The method does not use active carbon, when solvent is recovered, purified water is added into mother liquor for washing, and light phase is obtained by phase separation, so that the method can be repeatedly used for extracting filtrate, and the recovery is convenient. The invention discloses a method for extracting low-content erythromycin A from a fermentation solution, which comprises the following steps:
(1) and (3) filtering: filtering the fermentation liquor by a filter membrane with the molecular weight cut-off of 3-100 ten thousand, and collecting the filtrate;
(2) and (3) extraction: extracting the filtrate with organic solvent, adjusting pH to 8.0-12 with alkali, stirring to separate phases, and washing the light phase with saturated sodium chloride to obtain light phase solution;
(3) and (3) crystallization: adding water into the light-phase solution, controlling the temperature, then adding an acid solution to adjust the pH value, then adding thiocyanate to react, continuing to react after the addition is finished, then continuously adjusting the pH value to 3.0-6.0 by using the acid solution, crystallizing, filtering and drying to obtain the erythromycin thiocyanate.
As one embodiment, in the step (1) of the invention, the molecular weight cut-off of the filter membrane is 3-100 ten thousand, preferably in the range of 3-10 ten thousand, and the filter membrane is preferably a ceramic filter membrane; the temperature during filtration is 5-20 deg.C, preferably 8-12 deg.C.
As one embodiment, the amount of the organic solvent used in step (2) of the present invention is that the concentration of erythromycin in the organic phase is 25000-45000u/ml, preferably 28000-32000 u/ml; preferably, the organic solvent is butyl acetate, butanol, octanol, kerosene, ethyl acetate, or one or more of the above; butyl acetate, octanol or kerosene are preferred.
As one embodiment, the alkali in step (2) of the present invention is sodium hydroxide, potassium hydroxide; the sodium hydroxide solution is preferred, and the concentration of the sodium hydroxide solution is more preferably 15 to 25%.
As one embodiment, the pH value in step (2) of the present invention is further in the range of 8.0 to 12, preferably 9.5 to 11.5; the extraction temperature is 20-40 deg.C, preferably 30-35 deg.C.
As one embodiment, the amount of the saturated sodium chloride solution used in step (2) of the present invention is 5 to 50% (v/v), preferably 10 to 30%.
As one embodiment, step (3) of the present invention further comprises: during crystallization, adding purified water into the light phase, wherein the using amount is 0.1-2 BV, and preferably 0.8-1.2 BV;
as one embodiment, step (3) of the present invention further comprises: the temperature is 20-60 ℃, and preferably 30-40 ℃;
as one embodiment, step (3) of the present invention further comprises: after adding purified water, the pH is adjusted to 6.5-7.5 with an acid solution.
As one embodiment, the concentration of the sodium thiocyanate solution in step (3) of the present invention is 10 to 40%, preferably 15 to 25%;
as one embodiment, step (3) of the present invention further comprises: the molar ratio of the sodium thiocyanate to the erythromycin A is 1.0-2.0: 1, preferably 1.1 to 1.3: 1;
as one embodiment, step (3) of the present invention further comprises: the adding time is 5min-2h, preferably 50-70 min.
As one embodiment, step (3) of the present invention further comprises: and after the thiocyanate is added, continuously reacting for 0.5-1 h.
As one embodiment, step (3) of the present invention further comprises: after the salt forming reaction is finished, adjusting the end point to a pH value of 3-6 by using an acetic acid solution, and preferably, adjusting the end point to a pH value of 5-6.
As one embodiment, the acid in step (3) of the present invention is acetic acid; the concentration of acetic acid is preferably 15 to 25%, more preferably 20%.
As one embodiment, step (3) of the present invention further comprises: washing the filter cake with hot water at the temperature of 40-80 ℃, wherein the optimal temperature of the hot water is as follows: 45-55 ℃;
as one embodiment, step (3) of the present invention further comprises: filtering under vacuum of-0.08 MPa, and drying at 75-80 ℃ to obtain erythromycin thiocyanate meeting the specification.
As one embodiment, the method for extracting low-content erythromycin A from the fermentation solution comprises the following steps:
(1) filtration
Putting the erythromycin fermentation liquor into a tank, and then filtering the erythromycin fermentation liquor by a ceramic membrane, wherein the interception molecular weight of the ceramic membrane is 3-100 ten thousand, and the optimal interception range is 3-10 ten thousand; . The temperature of the feed liquid in the filtering process is 5-20 ℃, and the optimal temperature is 8-12 ℃;
(2) extraction of
Adding an extracting agent into the filtrate, wherein the extracting agent is one or more of butyl acetate, butanol, octanol, kerosene, ethyl acetate or the like, and preferably butyl acetate, octanol or kerosene; the dosage of the extractant is 25000 and 45000u/ml, preferably 28000 to 32000u/ml of the content of the erythromycin in the organic phase; adjusting pH to 8.0-12 with alkali solution, preferably pH 9.5-11.5; the temperature is 20-40 ℃, preferably 30-35 ℃; the alkali solution is sodium hydroxide and potassium hydroxide, preferably sodium hydroxide solution with the concentration of 15-25%; stirring for 10min, separating phase, and collecting light phase; washing the light phase with 5-50% (v/v) saturated sodium chloride solution, preferably 10-30%, stirring for 10min, separating phases, and collecting the light phase;
(3) crystallization of
Adding 0.1-2 BV of purified water, preferably 0.8-1.2BV, into the light phase at 20-60 ℃, preferably 30-40 ℃, and adjusting the pH value to 6.5-7.5 by using 15-25%, preferably 20% acetic acid aqueous solution; adding sodium thiocyanate solution with concentration of 10-40%, preferably 15-25%; the amount of sodium thiocyanate used was sodium thiocyanate: the molar ratio of erythromycin A is 1.0-2.0: 1, preferably 1.0 to 1.5: 1, further preferably 1.1 to 1.3: 1; the adding time is 5min-2h, preferably 50-70 min; after the addition is finished, continuing the reaction for 0.5-1 h, adjusting the end point to pH 3-6 by using 15-25%, preferably 20% acetic acid solution, preferably adjusting the end point to pH 5-6, and filtering; washing the filter cake with hot water at the temperature of 40-80 ℃, wherein the optimal temperature of the hot water is as follows: 45-55 ℃. Filtering, drying the wet powder for 2-3h at 75-80 ℃ under the vacuum of-0.08 MPa to obtain the erythromycin thiocyanate meeting the specification.
The method comprises the steps of filtering by a ceramic membrane, extracting by a solvent, washing by saturated sodium chloride, adding diluent purified water during crystallization, slowing down the crystallization speed, and obtaining the erythromycin thiocyanate finished product (a process flow chart is shown in figure 1). The method does not use activated carbon. When the solvent is recovered, purified water is added into the mother liquor for washing, and the light phase is obtained by phase separation, so that the method can be repeatedly applied to the extraction of the filtrate, and is convenient to recover.
The content of the erythromycin A in the finished product obtained by the method is more than 80 percent, the content of the erythromycin B and C is less than 3 percent, and the content of other impurities meets the pharmacopoeia standard.