PRODUCTION OF MICROBIAL METABOLITES AND
SJIF Impact Factor 4.897ejpmr, 2018,5(5), 80-88Sikander et al.Review ArticleEUROPEAN JOURNAL OF PHARMACEUTICALEuropean Journal of Pharmaceutical and Medical ResearchISSN2394-3211AND MEDICAL RESEARCHwww.ejpmr.comEJPMRPRODUCTION OF MICROBIAL METABOLITES AND OPTIMIZATION OF KEYFACTORS INVOLVING THEIR HYPERPRODUCTION IN BATCH CULTURE(REVIEW)*Sikander Ali, Maria Najeeb, Aiman Tahir Laghari, Maryam Salahuddin and Attia MajeedInstitute of Industrial Biotechnology, Government College University, Lahore.*Corresponding Author: Dr. Sikander AliInstitute of Industrial Biotechnology, Government College University, Lahore.Article Received on 05/03/2018Article Revised on 25/03/2018Article Accepted on 15/04/2018ABSTRACTFermentation is a metabolic process which uses the sugar in the absence of the Oxygen. However, it can be doneboth aerobically and anerobically. The products obtained from this process include organic acid, alcohol, gases andmany others by-products. One such industrially important by-product is metabolite production. Metabolites aresmall molecular weight compounds ( 2,500 amu) produced as an intermediate or end product of a metabolicreaction. Microorganisms during fermentation process produce not only primary metabolites but secondary, tertiaryand quaternary metabolites as well. These metabolites are industrially very important, however for industrialapplications the wild-type strains of micro-organisms need to be modifying by strain improvement techniques toenhance the productivity of commercially important compounds. This review will focus on the production ofprimary and secondary metabolites production with emphasis to the use of both liquid and solid state fermentationalong with the various approaches for the enhanced production of the metabolites. Factors such as pH, temperature,types of nutrients, carbon and nitrogen sources, growth factors, metabolic regulators, effect of water, presence ofother microbes, strain used and other parameters are also discussed in the view of hyper-production andoptimization of the metabolites.KEYWORDS: Primary metabolites, Fermentation, Trophophase, Vitamins, Secondary metabolites.INTRODUCTIONMetabolites are small molecular weight compounds( 2,500 amu) produced as an intermediate or end productof a metabolic reaction.[1] Microorganisms produced twomain types of metabolites such as primary and secondarymetabolites. These metabolites are produced duringdifferent phases of their growth. Primary metabolites areproduced during the log phase or trophophase of growthand are essential for the development of microorganism.These metabolites include amino acids, proteins,nucleotides, nucleic acids, carbohydrates and lipids.[2]Various primary metabolites are of industrial importanceand produced by fermentation at large scale as describedin Table 1. Metabolites produced by wild-typemicroorganism only fulfill the requirements of theproducing organism. But for industrial applications thiswild-type needs to be modifying by strain improvementtechniques to enhance the productivity of commerciallyimportant compounds.[3]primary and secondary metabolisms are interrelated asillustrated in Fig 1. Primary metabolites are produced bymajority of microorganism but secondary metabolites areproduced only by the filamentous bacteria and fungi aswell as by some sporing bacteria.[2]Secondary metabolites include antibiotic agents, gically important agents. These products arethe basis of various fermentation processes.Secondary metabolites are produced during thestationary phase also called the trophophase. Thesemetabolites are not required for the growth but havevarious industrial applications. Secondary metabolism isthe property of slow-growing microorganisms. Bothwww.ejpmr.com80
Sikander et al.European Journal of Pharmaceutical and Medical ResearchTable 1: Commercial applications of primary metabolites.Primary metaboliteApplicationAmino acidsFlavor enhancerL-glutamic acidGrowth enhancer and feed supplementL-lysineUsed in the feeds of pig and poultryL-threonineFeed additiveL-isoleucineFlavor enhancerNucleosides and nucleotidesFeed supplementsVitaminsOrganic acidsLactic acidVarious uses in the food industryCitric acidAcetic acid„Active ingredient‟ in alcoholic beverages. Used as aEthanolmotor-car fuel when blended with petroleumPrecursors of aspartame, sweetenerPhenyalanineApplications in the food industryPolysaccharidesEnhanced oil recoveryManufacture of drugs, food, cosmetics, paint and manyGlycerolother commoditiesUsed as a lubricant and solvent1, 3-propanediolNon-carcinogenic, non-caloric, and diabetic-safe sweetnerErythritolFigure 1: The interrelationship between primary and secondary metabolism. Primary catabolic routes areshown in heavy lines and secondary products are italicized.Secondary metabolitesBiosynthetic familiesMicroorganism produced chemically diversifiedsecondary metabolites. However, their biosyntheticpathways are linked to the primary metabolism.Following are the biosynthetic categories of SM:(1) Secondary metabolites derived from aromatic aminoacids (shikimic acid). For example, “ergot alkaloids”and the antibiotics chloramphenicol and candicin.(2) Metabolites derived from amino acids such as Blactam antibiotics (cephalosporins, penicillin andwww.ejpmr.comcephamycins) and cyclic peptide antibiotics(gramicidine and immunosuppressive agents)(3) Secondary metabolites obtained from Acetyl-CoA.This family of metabolites can be further subdividedinto “polyketides” and “terpenes”. Polyketidesinclude the antibiotic (erythromycin), theinsecticidal-antiparasitic compound (avermectin)and the antitumour agent (doxorubicin). An exampleof the terpenes is the non-cytotoxic antitumor agent(taxol).81
Sikander et al.European Journal of Pharmaceutical and Medical Research(4) Sugar derived metabolites such as streptomycin andkanamycin.[4]Since, the routes of biosynthesis of SM are related to theprimary metabolites, therefore both types of metabolitesuse the same regulatory mechanisms for control such asinduction, carbon source regulation and feedbackregulation.Production methodsLiquid fermentationSubmerged fermentation (SmF) by using batch or fedbatch culture techniques is the general method for theproduction of SM at industrial level. An inoculum ofimproved strain is prepared in the flasks containingmedium and then transferred to the “seed culture” orsmall fermenter. The culture, when in exponentialgrowth phase, is transferred to the production fermenterwith the range of 30,000 to 200000 liters. Parameterslike, temperature, pH, medium composition, aeration rateand agitation, are optimized. Environmental conditionsare manipulated for different regulatory mechanisms.[5]For cephalosporine fermentation, methionine as aninducer is added to the medium. Similarly, for thefermentation of chlortetracycline phosphate is restrictedand in case of penicillin production glucose is limited.Antibiotic fermentation processes are regulated byutilizing carbon sources such as lactose. Soybean meal isused as a nitrogen source to avoid regulation of nitrogen.Sometimes, concentration of a metabolite is increased bythe addition a particular precursor for example in case ofcephamycin production by Streptomyces calvuligeruslysine is added as a cofactor and precursor.[6] Specialturbine impellers are used for agitation and air suppliedat rates of 0.5-1.0 v/v per min. concentrations of O2 andCO2 are analyzed by the exit gas. In the subsequentstages some secondary metabolites are chemicallymodified to synthesize semi-synthetic derivatives.[5]Figure 2: A setup of Submerged Fermentation for the production of secondary metabolites.Solid-state fermentationSolid-state fermentation (SSF) is potentially s.[7,8,9] According to modern definition “SSF isa microbial culture that develops on the surface and atthe interior of a solid matrix and in absence of freewater”. SSF is divided into two types that depend on thenature of solid phase.[10](1) Solid-culture of one support-substrate phase—thesolid phase consists of a material that acts as bothwww.ejpmr.comsupport and nutrient source. Animal goods andwaste are used as solid phase(2) Solid culture of two substrate-support phase—thesolid phase consists of an inert support impregnatedwith a liquid medium. Inert support act as the sourceof nutrient and water. Sugarcane bagasse pith orpolyurethane can be utilized as inert support.SSF is suitable for actinomycetes and fungi, because theconditions are suitable for the growth of thesemicroorganisms. Some of the metabolites produced bySSF are given in (Table 2).82
Sikander et al.European Journal of Pharmaceutical and Medical ResearchFigure 3: A Schematic representation of Solid State Fermentation.Table 2: Biological activities of some microbial secondary metabolites of industrial importance.ActivityExamplesProducing MicroorganismCephalosporinAcremonium chrysogenumCephamycinStreptomyces clavuligerusChloramphenicolStreptomyces venezuelaeErythromycinSaccharopolyspora erythraeaKenamycinStreptomyces kanamyceticusAntibacterialsTetracyclinStreptomyces aureofaciensPenicillinPenicillium chrysogenumRifamycinAmycolatopsis mediterraneiSpectinomycinStreptomyces spectablisStreptomycinStreptomyces griseusLovastatinAspergillus terreusAnticholestrolemicsMonacolinMonascus ruberPravastatinPenicillium citrinumAmphotericinStreptomyces nodosusAspergillic acidAspergillus flavusAureofacinStreptomyces aureofaciensAntifungalsCandicidinStreptomyces griseusGriseofulvinPenicillium griseofulvumNystatinStreptomyces nourseOligomycinStreptomyces diastachromogenesActinomycin DStreptomyces antibioticusBleomycinStreptomyces verticillusAntitumoralsDoxorubicinStreptomyces peucetiusMitomycinStreptomyces lavendulaeTaxolTaxomyces andreanaeEnzyme inhibitorsClavulanic acidStreptomyces clavuligerusPlants Growth RegulatorsGibberellinGibberella fujikuroiMonensinStreptomyces cinnamonensisGrowth PromotersTylosinStreptomyces fradiaeHerbicidalsBialaphosStreptomyces hygroscopicusCyclosporin ATolypoclaudium inflatumImmunosuppresivesRapamycinStreptomyces hygroscopicusTacrolimus (FK-506)Several Streptomyces speciesAvermectinStreptomyces avermitilisInsecticides AntiparasiticsMilbemycinStreptomyces hygroscopicusAstaxanthinPhaffia rhodozymaPigmentsMonascinMonascus purpureusFactors effecting production of metabolitesEffect of pHpH is actually the measure of the acidity and alkalinity ofa solution. pH has a great affect in the fermentationwww.ejpmr.comprocess for metabolite productioneven a slight change inthe pH can cause the toxicity or cease the reaction,therefore pH is needed to be optimized.[11] For theproduction of ethanol that is a commercially important83
Sikander et al.European Journal of Pharmaceutical and Medical Researchprimary metabolite the enzymes only work best in theacidic conditions. This is due to the acidic conditionprovided by the pyruvic acid. Most of the fermentationprocesses if the pH drops below 4.2 and therefore theoptimum pH for fermentation is about 4.8 - 5.0.[12] Butagain each strain i.e bacterial or yeast used for thefermentation has their own optimum pH.The pH will not only affect the strains and species usedfor the fermentation process but will also affect theirmetabolic activities as well. Different strains havedifferent optimum pH, for instance the Oenococcus cantolerate low pH easily as compare to the lactobacilli orpediococci.Figure 4: Effect of pH on metabolite production.Effect of temperatureTemperature changes have an intense effect on the livingthings. Enzyme-catalyzed reactions are particularlysensitive to the small changes in the temperature. Thetemperature can affect the process of fermentation in thefollowing ways: (1) Effect of high temperature (2) Effectof Low temperature (3) Optimal Temperature (4) Controlof Temperature (5) Temperature and pH.For the production of secondary metabolites totalbiomass production should be low that could be achievedeither at very low or high temperature because at thistemperature enzymatic function is ceased that effect boththe production of primary metabolites and biomass. Forthe production of wine the organisms will be able togrow rapidly at high temperature but it‟ll affect thequality of wine and deteriorate it. In case of the yeast,low temperature is preferred. However, the rate offermentation should increase with the increase intemperature from the 10 C to 40 C while at 50 C andtemperature above than this the rate of the fermentationwill decrease.Figure 5: Effect of temperature on the production of metabolites.Types of the Nutrients and their effectsSimple NutrientsThere are six basic nutrients needed which includesCarbohydrate, proteins, fats, vitamins, water andminerals for the fermentation process. Their sources willbe explained later.www.ejpmr.comComplex NutrientsThere are few media which are complex and are neededin the fermentation. They are chemically synthesized andare specially provided in the fermentation process. Justas an example of the lactic acid bacteria, which requirethe compound 4‟-O-(β-D-glucopyranosyl)-D-pantothenic84
Sikander et al.European Journal of Pharmaceutical and Medical Researchacid which is found in tomato juice and in other fruitjuices. It is actually a growth factor needed by the lacticacid bacteria.[13] Therefore the media used for thecultivation of the lactic acid bacteria usually containapple or tomato juice as essential components. If theyeast is present in the media it will interfere with theproduction of the lactic acid and may deplete it but if thelysis of the yeast[14] occur as in wine making than thelactic acid will again be activated however if thenutritional content is low than the growth of lactic acidmay slow down. Other complex media also contain thehigh juice solids content and the extended skin contactwhich increase the nutritional content for the lactic acidbacteria and increase its growth as well.[15]Effect of water in the Fermentation processWater is one of the important components in thefermentation process and is used in the fermentation formany processes like the cooling, heating and rinsing.Therefore clean and a continuous supply of water isneeded in order to maintain the salt dissolution, pH andother effluent contamination.The mineral content of the water is quite important in theprocess of brewing. And it is very critical in the processof mashing. These days, water is also been treated withthe deionization or many other techniques, additives likesalts are also added and pH is also varied to get therequired product and different flavors of beer.Reuse of water is also an important factor affecting thefermentation process.[16,17]Carbon Source and its effectThe rate at which carbon source is utilized can affect theformation of the biomass or the other products likeprimary and secondary metabolites obtained from thefermentation process. If the sugars are being highlyutilized then it will lead to the low productivity of thesecondary metabolites[18] (Table 3). Therefore, alternativemethods are opted for the producer organism to give thehigh yield.Table 3: Carbon catabolite regulation of metabolite biosynthesis.MetaboliteMicroorganismInterfering carbon sourceGriseofulvinPenicillium ephalosporinCephalosporium acremonium GlucoseAurantinBacillus aurantinusGlycerola-amylaseB. licheniformisGlucoseBacitracinB. licheniformisGlucosePuromycinStrptomyces albonigerGlucoseActinomycinS. antibioticusGlucoseCephamycin CS. clavuligerusGlycerolNeomycinS. fradiaeGlucoseCycloserineS. ycinS. kenamyceticusGlucoseNovobiocinS. niveusCitrateNitrogen SourcesMost of the industrial micro-organisms either use organicor inorganic nitrogen sources for fermentation Ammoniagas has been used as an inorganic source, which is notonly used in the define medium but also used to maintainthe pH. Apart from ammonia, ammonium salts andnitrates are also being used.[33]According to a research the production of antibiotics byvarious microorganisms depends on the type and lizing nitrogen sources such as ammonium ion(NH4 ), nitrate ion and various amino acids can beinhibitory for the production of antibiotics. In a culturemedium the production of antibiotics only starts whenthe entire nitrogen source has been utilized.ReferenceRhodes et al[19]Pirt and Rhigelato[20]Matsumura et al[21]Nishikiori et al[22]Priest and sharp[23]Weinberg[24]Sankaran and Pogell[25]Marshell et ne et al[30]Basek and Majumdar[31]Kominek[32]physiological conditions in trophophase that favors theenhanced production of antibiotic in the idiophase.[35] Forthe production of polyene antibiotics, the soybean mealhas been considered the most favorable source due thebalance of nutrients, low ratio of phosphorus and the lowrate of hydrolysis. The process of slow hydrolysisprevents the piling up of ammonium ions and inhibits the“repressive amino acids”. Therefore, selection of an idealnitrogen source is necessary for the production ofsecondary metabolites. (Table).[36] Mostly the use ofcomplex nitrogen sources is avoided due to thedownstreaming and the effluent treatment problems.Consumption of complex nitrogen sources for theproduction of antibiotic helps to establish thewww.ejpmr.com85
Sikander et al.European Journal of Pharmaceutical and Medical ResearchTable 4: Best nitrogen sources for some secondary metabolites.ProductMain nitrogen sourcePenicillinCorn-steep liquorBacitracinPeanut granulesRiboflavinPancreatic digestNovobiocinDistillers solublesRifamycinPharmamediaSoybean meal, Ammonium salt andGibberellinsnatural plant nitrogen sourceButirosinDried beef blood or haemoglobinPolyenesSoybean mealMinerals and their effectIn the fermentation the micro-organisms need theminerals to complete the process. The minerals which arenormally needed by the micro-organisms includemagnesium, calcium, phosphorous, sulphur, potassium,and chlorine are the essential minerals needed by themicro-organisms. Some other minerals are copper,cobalt, manganese, iron, zinc and molybdenum.[43] Theyare also essential but the impurities introduced by themnot only cause the toxicity in the fermentation media butalso affect the quality and yield of product of thefermentation.[44] Some of the minerals like phosphate areadded in the media to act as a buffer which would helpmaintain the pH of the fermentation process.For the production of secondary metabolites choice andconcentration of some minerals is very critical becausethey have low tolerance range for various inorganicphosphates. According to Gray et al.,[45] the productionof streptomycin can be improved by precipitating out theexcessive inorganic phosphates by using calcium ions.Liras et al.,[46] reported that phosphate also have theability to inhibit or repress the enzymes of a metabolicpathway. Sometimes, chlorine is used to supress theformation of non-chloro compounds. For example in theproduction of griseofulvin about 0.1% KCl is used tofulfil the requirement of chlorine.[47]Growth factors and their effectsSome micro-organisms are not able to synthesis all thecomponents therefore they need components and thesecomponents are called the growth factors. The mostcommon growth factors are vitamins, fatty acids, aminoacids and sterols.[48] Micro-organisms may either utilizeall of these factors or they need few of them to growproperly. Most of the nitrogen and carbon sourceshowever provide all the necessary components for thegrowth of the microbe. However, if the vitamindeficiency occurred then it is mostly eliminated by thecareful blending. It should be noted that if only onevitamin is needed by the fermentation process than it isrecommended to use the pre vitamin itself rather than amixture example thiamine and glutamic acid etc.Thus, the depletion of any of the nutrients, their excessor their toxicity will highly affect the fermentationprocess.www.ejpmr.comReferenceMoyer and Coghill[37]Inskeep et al[38]Malzahn et al[39]Hoeksema and Smith[40]Sensi and Thiemann[41]Jefferys[34]Claridge at al[42]Martin and MacDaniel[33]Approaches to improve the yield of secondarymetabolitesStrain improvementStrain improvement is a science or technology used tomanipulate the microbial strains to enhance theirmetabolic capacities for biotechnological applications.Increased production of desired metabolite is the mainpurpose of strain improvement.[49] These days, twostrategies can be alternatively employed for thedevelopment of improved strain: (1) Classical geneticmethods (2) molecular genetic methods.Classical genetic methodsIn these methods, mutation of particular strain isfollowed by random screening. Further, fermentationtests are performed to select the best improved strain.Physical mutagens such as ethyl methanesulphonate andnitrosoguanidine can be used for the induction ofmutation.[50] Main advantages of mutation are itssimplicity, requirement of sophisticated equipment andits effectiveness. Development of these methods requiresthe basic knowledge of product metabolism and thepathway through which it is produced. Randomscreening methods remove all the undesired genotypesand only select the particular desired one strain.Microorganism possesses regulatory mechanisms thatprevent the overproduction of a particular metabolite.However, it has been reported that through mutationthese mechanisms can be eliminate or decreased to favorthe overproduction of a primary metabolite. But forsecondary metabolites the nutritional conditions ofculture are manipulated because the control mechanismsfor secondary metabolite production are morecomplex.[51] Genetic recombination methods are alsoimportant complement to mutagenesis. In these methodsa strain is constructed that has combinations ofmutations. Recombination through protoplast fusion isone the most common method used for strainimprovement. In this method a strain that is alreadyimproved by genetic methods is fused with a new isolateto enhance its production capacities.[52]Molecular genetic methodsAdequate vectors, identification of the biosyntheticpathway and effective transformation protocols arerequired for the application of molecular geneticmethods. After this, biosynthetic genes are cloned and86
Sikander et al.European Journal of Pharmaceutical and Medical Researchanalyzed. Following are some strategies used for strainimprovement:(1) Characterization of high producing strains. Byemploying genetic engineering, genes responsiblefor antibiotic synthesis are grouped together in“fungi” and “actinomycetes”. For example, inpenicillin producing strains of penicillumchrysogenum AS-P-78 the cluster of biosyntheticgenes has been amplified.[53](2) Targeted amplification of secondary metaboliteproducing strains by using two different approachessuch as amplification of targeted gene andamplification of whole pathway.(3) Inactivation of competing pathway. By using thesemethods a pathway competing for metabolites canbe blocked. This can be achieved by gene disruption,insertion of an antisense synthetic gene and bytransposon mutagenesis.[54](4) An alternative of blocking method is theamplification of a regulatory gene.(5) Strain improvement can also be done by theintroduction of a heterologous gene. Expression ofheterologous gene leads to the production of a newproduct that is industrially important. But thisprocess is chemically difficult and expensive.[55](6) In combinatorial biosynthesis, non-conventionalcompounds are used as substrate for the productionof a new . El-Mansi EMT, CFA Bryce, B Dahhou, S Sanchez,AL Demain, AR Allman. Microbial Synthesis ofPrimary Metabolites: Current Trends and FutureProspectives. In: Fermentation Microbiology andBiotechnology. CRC Press Taylor & Francis Group,London New York, 2011; 78-99.2. Bu‟ Lock JD, D Hamilton, MA Hulme, AJ Powell,D Shepherd, HM Smalley, GN Smith. Metabolicdevelopment and secondary biosynthesis inPenicillium urticae. Can. J. Micro, 1965; 11:765-778.3. Stanbury PF, A Whitaker. Introduction toFermentation Technology. In: Principles offermentation technology. (2nd Ed). Pergamon Press,London New York, 1984; 3-10.4. Beri RK, G Turner. Transformation of PenicilliumChrysogenum using the Aspergillus nidulans and Sgene as a dominant selective marker. Curr. Genet,1987; 11: 6390-6411.5. Khetan A. Precursor and cofactor as a check valvefor cephamycin biosynthesis in Streptomycesclavuligerus. Biotechnol. Prog., 1999; 15:1020-1027.6. Barrios-Gonzalez J. Penicillin production by solidstate fermentation. Biotechnoi. Leu, 1988; 10:793-798.7. Tomasini A. Gibberellic acid production usingdifferent solid state fermentation systems. World. J.Microbiol. Biotechnol, 1997; 13: son T. Solid-state fermentation: a promisingmicrobial technology for secondary metaboliteproduction. Appl. Microbiol. Bitechnol, 2001; 55:284-289.Barrios-Gonzalez J, A Mejia. Production ofsecondary metabolites by solid-state fermentation.Biotechnoi. Annu. Rev, 1996; 2: 85-121.AI Oparin. Origin of Life: Dover Publications. NewYork, 1965.Thomas KC, SH Hynes, WM Ingledew. Influence ofmedium bufferingcapacity on inhibitionof Saccharomyces cerevisiae growth by acetic andlactic acids. Appl. Environ. Microbiol, 2002; 68:1616-1623.Vander HMG, LC Cantley, CB Thompson. 2009.Understanding the Warburg effect: the metabolicrequirements of cell proliferation. Sci, 2009;324(5930): 1029-1033.Ulf S, W Lorri. Fermentation and NutrientAvailability: Food Control, 1997; 6(8): 319-327.Ezeronye OU. Nutrient utilization profile ofSaccharomyces Cerevisiae from palm wine intropicalfruitfermentation:Antonievanleeuwenhoek, 2004; 86(3): 235-9.Hamer G. Biomass from natural gas.Eco.Microbiol, 1979; 4: 315-360.Levi JD, JL Shennan, GP Ebbon. Biomass fromliqid n-alkanes. Eco. Microbiol, 1979; 4: 361-419.Johnson MJ. Recent advances in penicillinproducing moulds. Ann. N.Y. Acad. Sci, 1952; 48:57-66.Hunter SH. Inorganic nutrition. Ann. Rev.Microbiol, 1972; 26: esis. Prog. Industr. Microbiol, 1963; 4:165-187.Pirt SJ, Rhigelato RC. 1967. Effect of growth rate onthe synthesis of penicillin by penicilliumchrysogenum in batch and chemostat cultures. Appl.Microbiol, 1967; 15: 1284-1290.Matsumura M, Imanaka T, Yoshida T, Taguchi H.Effect of glucose and methionine consumption rateson cephalosporin C production by cephalosporiumacremonium. J. Ferm. Technol, 1978; 56: 345-353.Nishikiori T, Masuma R, Oiwa R, Katagiri M,Awaya J, Iwai Y, Omura S. Aurantinin, a newantibiotic of bacterial origin. J. Antibiot., 1978; 31:525-532.Priest FG, Sharp R J. Fermentation of bacilli. InFermentation Process Development of IndustrialOrganisms, 1989: 73-112. (Editor Neway, J. O.).Plenum. London.Weinberg ED. Biosynthesis of secondarymetabolites: roles of trace metals. Adv. Microbial.Phy, 1970; 4: 1-44.Sankaran L, Pogell BM. Biosynthesis of puromycinin Streptomyces alboniger: Regulation se.Antimicrobiol.Agents.Chemother, 1975; 8: 727-732.87
Sikander et al.European Journal of Pharmaceutical and Medical Research26. Marshall R, Redfield B, Katz E, Weissback H.Changes in phenoxazinone synthatase activityduring the growth cycle of Streptomycesantibioticus. Arch. Biochem. Biophys., 1968; 123:3170-323.27. Aharonowitz Y. Nitrogen metabolite regulation ofantibiotic biosynthesis. Ann. Rev. Microbiol, 1980;34: 209-233.28. Majumdar M K, Majumdar SK. Effects of mineralson neomycin production by Streptomyces fradiae.Appl. Microbiol, 1965; 13: 190-193.29. Svensson ML, Roy P, Gatenbeck S. Glycerolcatabolite regulation of D-cycloserine production inStreptomyces garphalus. Arch. Microbial, 1983;135: 191-193.30. Inamine E, lago B D, Demain AL. 1969. Regulationof mannosidase, an enzyme of streptomycinbiosynthesis. In Fermentation Advances, 1969; 199221 (Editor Perlman, D.). Academic Press, NewYork.31. Basak K, Majumdar SK. Utilization of carbon andnitrogen sources by Streptomyces kenamyceticus forthe kanamycin production. Antimicrobiol. Agent‟schemother, 1973; 4: 6-10.32. Kominek LA. 1972. Biosynthesis of novobiocin byStreptomyces niveus: Antimicrobial. Agent‟schemother, 1972; 1: 123-134.33. Martin JF, McDaniel LE. Production of polyenemacrolide antibiotics. Adv. Appl. Microbiol, 1977;21: 1-52.34. Jefferys EG. The gibberellin fermentation. Adv.Appl. Microbiol, 1970; 13: 283-316.35. Miller TL, BW Churchill. Substrates for large Scalefermentations. Manual of Industrial Microbiology:American Society of Microbiology, Washington,DC 1986.36. Gray PS. Impact of EEC regulations on theeconomics of fermentation substrates. In carbonsubstrates in Biotechnology, 1987; 1-27 (editorsStowell, J. D. Beardsmore, A. J. , Keevil, C.W andWoodward, J. R). IRL Press, Oxford.37. Moyer AJ, Coghill RD. Improvements in or relatingto the manufacture of riboflavin. British Patent,1946; 615: 847.38. Inskeep GC, Bennet RE, Dudley JF, Shepard MW.Bacitracin, product of biochemical engineering. Ind.Eng. Chem, 1951; 43: 1488-1498.39. Malzahn RC, Phillips RF, Hanson AM. Riboflavin.U. S. Patent, 1959; 2: 876, 169.40. Hoeksema H, Smith CG. Novobiocin. Prog. Industr.Microbiol, 1961; 3: 91-139.41. Sensi P, Thiemann JE. Production of Rifamycins.Prog. Industr. Microbial, 1967; 6: 21-60.42. Claridge CA, Bush JA, Difuria MD, Price KE.Fermentation and mutation studies with a bitrusinproducing strain of Bacillus circulans. Dev. Industr.Microbiol, 1974; 15: 101-113.43. Liras P, Astruias JA, Martin JF. Phosphate controlsequences involved in transcriptional regulation .antibiotic biosynthesis. Trends Biotech, 1990; 8:184-189.Attikson B, F Mavituna. Process biotechnology.Biochemical Engineering
and produced by fermentation at large scale as described in Table 1. Metabolites produced by wild-type microorganism only fulfill the requirements of the producing organism. But for industrial applications this wild-type needs to be modifying by strain improvement techniques to enhance the productivity of commercially important compounds.
PART I The Scope of Microbiology 1 1 Evolution, Microbial Life, and the Biosphere 3 2 Historical Overview 31 3 Fundamental Chemistry of the Cell 55 4 Structure and Function of Bacteria and Archaea 75 PART II Microbial Physiology: Nutrition and Growth 123 5 Nutrition, Cultivation, and Isolation of Microorganisms 125 6 Microbial Growth 153 7 Control of Microbial Growth 179
mycotoxins in soil into an ecological perspective (Susanne Elmholt). Two chapters are devoted to plant metabolites: Franz Hadacek' review deal with the biological effects of constitutive plant metabolites and Jorge Vivanco's group remind us that root exudates, which is the group of plant metabolites largely neglected by phytochemists,
ICH M3(R2) step 4, 2009 Robinson TW, Jacobs A, Metabolites in safety testing, Bioanalysis, 2009 ICH M3(R2) Q&A, 2011 Safety Testing of Drug Metabolites Guidance (revised to align with ICH M3(R2)), 2016 www.fda.gov
Natural Drugs Natural Products Chemistry Isolation / purification of secondary metabolites Structural elucidation and characterization of secondary metabolites (spectroscopic properties, stereo-chemistry, etc.) Structural modification Chemical synthesis Biosynthesis and microbial transformation Analytical Chemistry .
Thus the focus could range from marine and coastal microbial ecology to terrestrial ecology to microbial symbioses. The course focuses on bacteria and viruses; less so on fungi, and protists; and briefly touches upon phytoplankton. One of the emerging new paradigms of microbial ec
vTABLE OF CONTENTS TEST BANK CHAPTER 1 Microorganisms and Microbiology T-1 CHAPTER 2 Microbial Cell Structure and Function T-17 CHAPTER 3 Microbial Metabolism T-34 CHAPTER 4 Molecular Microbiology T-49 CHAPTER 5 Microbial Growth and Growth Control T-66 CHAPTER 6 Microbial Genomics T-83 CHAPTER 7 Me
1 Chapter 6: Microbial Growth Microbial Growth: 4Refers to an increase in cell number, not in cell size. 4Bacteria grow and divide by binaryfission, a rapid and relatively simple process. Requirements for Growth Physical Requirements 1.Temperature: Microbes are loosely classified into several groups based on their
erosion rate of unmasked channels machined in borosilicate glass using abrasive jet micro-machining (AJM). Single impact experiments were conducted to quantify the damage due to the individual alumina particles. Based on these observations, analytical model from the an literature was modified and used to predict the roughness and erosion rate. A numerical model was developed to simulate the .
