توليد بيولوژيكي اسيد لاكتيك از چوب درخت كاج با استفاده از قارچ و بهينه سازي شرايط فرآيند

چكيده انگليسي :

Biological Production of Lactic Acid from Pine Wood by Fungi and its Optimization Amir Hossein Falahi ah falahi@ce iut ac ir Date of submission 2012 3 12 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language PersianSupervisor Arjomand Mehrabani Zeinabad arjomand@cc iut ac ir Keikhosro Karimi karimi@cc iut ac irAbstractLactic acid 2 hydroxypropionic CH3CHOHCOOH is the most widely utilized organic acid in the food pharmaceutical cosmetics and chemical industries Its production is currently attracting a great deal of researchand development Lactic acid exists naturally in two optical isomers d lactic acid and l lactic acid Sinceelevated levels of the d isomer are harmful to humans l lactic acid is the preferred isomer for food related andpharmaceutical industries Lactic acid can be produced commercially by either chemical synthesis orfermentation The chemical synthesis results in a racemic mixture of the two isomers while the fermentationprocess can yield an optically pure form of lactic acid or racemate depending on microorganisms substrates andfermentation conditions employed in the production process Renewable resources including sugars starch andlignocellulose are abundant substrates for fermentative production The most commonly used synthetic methodfor chemical production of lactic acid is the hydrolysis of lactonitrile derived from acetaldehyde and hydrogencyanide which are produced by petrochemical process Therefore chemical synthesis may be limited due to ashortage of the naturally available raw materials in the future Lactic acid can be produced using bacteria andfungi Lactic acid producing bacteria LAB have received wide interest because of their high growth rate andproduct yield This expensive downstream process increases the overall cost of production of lactic acid usinglactic acid producing bacteria Fungal Rhizopus species have attracted a great interest and have been recognizedas suitable candidates for lactic acid production Unlike the LAB lactic acid producing Rhizopus strains generatel lactic acid as a sole isomer of lactic acid In the second of 20th century lactic acid knew as the component ofmetabolism and common material of various industries like pharmaceutical industry food industry leatherindustry and medical industry to prepare medical instrument lactic acid L is prevalent in food andpharmaceutical industries while lactic acid D is used in leather and textile industries Furthermore the type ofpolymer of lactic acid PLA is applied in clinic cases and also to manufacture medical instrument The mainresources to produce lactic acid are sugars starch and lignocellulosic materials In this project production oflactic acid from pine wood by fermentation was investigated The wood was pretreated enzymaticallyhydrolyzed and fermented by two different fungi Similar to other lignocellulosic materials the wood composedof three major groups of polymers i e cellulose polymer of glucose hemicelluloses polymer of pentose andhexose sugars and lignin Concentrated phosphoric acid pretreatment at modest reaction conditions and alkalinepretreatment by NaOH were used Then the pretreated pine woods were subjected to enzymatic hydrolysis usingcommercial cellulase and glucosidase enzymes The hydrolyzates were then fermented by Rhizopus fungi Untreated pine wood without any pretreatment was also hydrolyzed by the enzymes and then fermented Theanalysis of the treated woods showed the maximum glucan yield of 43 by alkaline pretreatment where as thetreatment with phosphoric acid resulted in a substrate with 40 glucan Thus both of the treatment resulted inhigher glucan substrate compared to the untreated wood which contain 35 glucan The enzymatic hydrolysis ofphosphoric acid and alkaline pretreated wood resulted in 46 and 19 glucose yields respectively which washigher than that for untreated wood 6 Fermentation of the hydrolyzates resulted in 326 grams lactic acid perkg of

فلاحي، اميرحسين

توليد بيولوژيكي اسيد لاكتيك از چوب درخت كاج با استفاده از قارچ و بهينه سازي شرايط فرآيند

رايزوپوس , پيش فرآوري , هيدروليز آنزيمي , تخمير