Study On Process Of Propionic Acid Fermentation And Extract

The propionic acid is an important industrial product, which is mainly produced by chemical methods. With the lack of fossils, the bio-manufacture of chemical products is becoming more and more important. The process of propionic acid fermentation has been the hot topic, but it has not yet been industrialized because of low concentration in fermentation broth, difficult separation, high cost and environment pollution. Therefore, increasing concentration of propionic acid in fermentation broth, improving extraction yield and lowering the production cost are the most urgent and important problems in modern industries. In this paper, the expansion culture of P. shermanii, extraction and purification of propionate and acetate in the fermentation were studied mainly. The main research results are as follows:1)A simple, accurate chromatography method was established to detect propionic acid and acetic acid. The method was repeatable, simple and suitable for process monitoring of fermentation and extraction.2)A simple, fast, accurate method for determination of adenosylcobalamin (vitamin B₁₂) in P. shermanii fermentation broth was developed by high performance liquid chromatography（HPLC）. Sample was analyzed by HPLC after simple pretreatment without cyanide transformation. Sample could be well separated by the methed in 7 min. The method was suitable for process monitoring of fermentation and extraction.3)Based on the flask condition, the batch fermentation of P. shermanii was performed in 2.5L bioreactor, Compared with the fed-batch fermentation technology in flask whose initial glucose was also 8%, the final cell wet weight, vitamin B₁₂. propionic acid and acetic acid concentration was slightly increased. The impact of sugar-fed-batch fermentation technology on the acid and VB₁₂ yield by P. shermanii was studied in bioreactor. The initial glucose concentration was 4%, then added 2% glucose since the fermentation time at 36 h and 60 h respectively. The production of propionic acid reached to 4.25%, the cell wet weight was 9.89% and the vitamin B₁₂ production was 54.3μg/mL.4)A distillation and concentration technology of propionic acid and acetic acid from fermentation broth was introduced. In this process, fermentation broth was preliminary concentrated and ammonia was recoverd. The recovery rate of ammonia was 90.8% and the yield of propionic acid and acetic acid was near 100%.5)After screening from four types of decolorant, we found irregular granular activated carbon exhibit high decoloring ratio and high propionic acid and acetic acid yield. The optimum conditions of active carbon decolor methed were: temperature 50℃～60℃, pH 6.0, flow velocity 2BV（Bed Volume）/h, loading volume 6BV. Under the optimum condition, decoloring ratio reached 94.6%, propionic acid yield reached 94.0%, acetic acid yield reached 94.1 %.6)By adopting the whole technology to procedure propionate and acetate, the total yield of propionic acid was 76.1% and 75.8% of acetic acid, the finial purity was 79.5% of propionate and 79.9% of acetate.In conclusion, the enlarge culture of P. shermanii and extraction technology were studied mainly in this paper. The final propionic acid, acetic acid and vitamin B₁₂ yield had been increased, and the fermentation cycle was shortened. A extraction technology for propionate and acetate from fermentation broth by distillating, concentrating and drying was established.