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Unformatted text preview: APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Aug. 1980,p.294-300 Vol.40, No. 2 0099-2240/80/08-0294/07$02.00/0 NutritionalInterdependence Among Rumen Bacteria, Bacteroidesamylophilus,Megasphaera elsdenii,and Ruminococcusalbus HIDEKI MIURA, MASAAKI HORIGUCHI, AND TATSURO MATSUMOTO* DepartmentofAnimalScience,FacultyofAgriculture, Tohoku University,Sendai980,Japan Nutritional interdependence among three representatives ofrumen bacteria, Bacteroidesamylophilus,Megasphaera elsdenii,and Ruminococcus albus,was studiedwithabasalmedium consistingofminerals,vitamins,cysteinehydrochlo- ride,and NH4'.B. amylophilus grew wellinthebasal medium supplemented withstarchandproducedbranched-chainaminoacidsaftergrowthceased.When coculturedwithB. amylophilus inthebasalmedium supplemented with starch andglucose,amino acid-dependentM. elsdeniiproducedanappreciableamount ofbranched-chainfattyacids,which areessentialgrowth factorsforcellulolytic R.albus.A smalladditionofstarch(0.1to0.3%)tothebasalmedium containing glucoseandcellobiosebroughtaboutsuccessivegrowthofthethreespeciesinthe order ofB. amylophilus,M. elsdenii,and R. albus,and successivegrowth was substantiatedbytheformationofbranched-chain amino acidsandfattyacidsin the culture. Supplementation with 0.5% starch, however, failedto support the growth ofR. albus. On the basisofthese results,the effectsofsupplementary starch or branched-chain fattyacids on cellulose digestion in the rumen was discussed. Although most cellulolytic rumen bacteria havebeenprovedtohaveabsoluterequirements for branched-chain fatty acids (4, 10, 11, 19) producedbythedeaminationofbranched-chain amino acids by other organisms (2), a large number of cellulolytic bacteria which require thesefattyacids(28,29)aswellasaconsiderable amount ofthe branched-chain fattyacids (16) have been found in the rumen ofanimals fed dietsdevoidofthefattyacidsand oftheirbio- syntheticprecursoraminoacids.Cellulosediges- tion in vitro by rumen bacteria has also been reportedtobestimulatedbyasmalladditionof starchtoamedium containingurea as thesole sourceofnitrogen(5,6,17).One possibleexpla- nationforthesephenomena would be thatcell proteinsofsome ofthebacteria,suchasBacte- roidesamylophilus,capableofsynthesizingpro- tein from starch and NH4' (8, 13), are the sources ofbranched-chain amino acids,which are decomposed to produce the essential branched-chain fatty acids by deaminase-posi- tivebacteria,suchasMegasphaeraelsdeniiand Bacteroidesruminicola (3). The presentinvestigationwas undertaken to seeifsuch a nutritionalinterdependence could take placeamong B. amylophilus,M. elsdenii, andcellulolyticR.albus. MATERIALS AND METHODS Organisms and culture methods. B. amylophi- lus70,M. elsdeniiT81,andR.albus7wereobtained fromtheculturecollectionoftheDepartmentofDairy Science, University of Illinois. The organisms were growninmedium 10(15)exceptthatagarwasomitted and the concentrations ofstarch, glucose, and cello- biosewere increasedto0.3% (wt/vol) each.The cells were harvested in the logarithmic growth phase by...
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This note was uploaded on 09/19/2011 for the course ANS 5446 taught by Professor Brown during the Spring '08 term at University of Florida.
- Spring '08