Microbiology Dan Keju

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3.35 (SD 1.98), 80.91 lbs (SD29.2), 207 days (SD 139.59), and 24,321 lbs (SD 5022) respectively. Herd, Parity, DIM and DIM were all significant effects in the model (P .01). Of the hygiene score traits Tail head, Flank and Belly were not significant. However, as Udder, Rear legs, and Udder - Rear legs composition scores increased SCS also increased. For each 1 standard deviation increase in Udder, Rear legs or Udder - Rear legs composition score, SCS increased by 0.13, 0.17 and 0.17, respectively
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  3.35 (SD 1.98), 80.91 lbs (SD29.2), 207 days (SD 139.59), and 24,321 lbs(SD 5022) respectively. Herd, Parity, DIM and DIM were all significanteffects in the model (P < .01). Of the hygiene score traits Tail head,Flank and Belly were not significant. However, as Udder, Rear legs,and Udder - Rear legs composition scores increased SCS also increased.For each 1 standard deviation increase in Udder, Rear legs or Udder- Rear legs composition score, SCS increased by 0.13, 0.17 and 0.17,respectively. Similar herds with predominance of environmental mas-titis infections and similar somatic cell count levels may expect to seea 40-50,000 change in herd SCC for each 1-unit change in cow hygienescores. Key Words: SCC, Cow hygiene score W260 Implementation of a pilot Dairy QualityManagement Program in Maryland. R. R. Peters* 1 , R. A.Kohn 1 , J. W. Simms 1 , D. M. Schwartz 1 , S. W. Fultz 1 , M. R. Bell 1 ,J. E. Hall 1 , J. Fearer 2 , D. Booth 2 , M. Clarke 2 , K. Hendricks 2 , andD. Shinham 2 , 1 University of Maryland, College Park, MD, 2 Maryland Department of Agriculture, Annapolis, MD  . A one-year pilot Dairy Quality Management Program (DQMP) waslaunched starting with a one-day training program for five Marylanddairy producers and their advisors on July 3, 2001. The training pro-gram focused on three programmatic areas: biosecurity, animal health,and animal nutrient management. As a pilot program, it was empha-sized that a major objective for everyone was experiential learning. Theteam approach to problem solving was implemented to enhance learn-ing. Dairy advisory teams usually included six professionals. The ini-tial team meeting with the producer started with a survey of farm andherd health information, herd goals and concerns, employee manage-ment, a farmstead map, detailed maternity and heifer-calf managementpractices, and ranking of current herd health concerns. Subsequently,a walk-through progressing from youngest to oldest animals was con-ducted with the advisory team using risk assessment forms. At thecompletion of risk assessment, the team convened with the farm fam-ily. Areas in need of improvement were discussed from two perspectives:most important for animal health risk and most practical for producerto improve. As assessments were completed, the advisory team out-lined a herd plan with three to five goals supporting the overall herdgoals initially discussed with the producer. The herd plan included theperson responsible for task implementation, deadline for implementingthe practice and the frequency to conduct task. Rations were examinedand milk urea nitrogen was measured monthly to evaluate herd nutri-tion. The producer and team met at least quarterly to monitor progress.A personal interview was completed for each herd using producer atti-tude and herd plan as criteria for evaluation. All producers expresseda positive experience with DQMP. Farms changed 1 to 7 (median = 3)management or facility changes per farm. It is concluded that producerswill adopt and implement DQMP on their farms. Key Words: Dairy, Quality, Management Dairy Foods: Microbiology and Cheese W261 EPS and lactic acid production by S. ther-mophilus 1275: influence of pH, temperature, nutrients andco-culturing with non-EPS starter. B. Zisu* 1 , G. Harvey 2 , andN. P. Shah 1 , 1 Victoria University, Melbourne, Australia, 2 Dairy Farm-ers, Tingalpa, Queensland, Australa . Lactic acid bacteria that synthesise exopolysaccharides (EPS) are usedincreasingly in the dairy industry to improve rheological behaviour,mouthfeel and texture of fermented milks. We have identified a strainof  Streptococcus thermophilus 1275 which produces both capsular andextracellular EPS.The objective of this study was to examine EPS and lactic acid pro-duction by S. thermophilus 1275 in skim milk under various pH andtemperatures, supplementation with whey protein concentrate (WPC)and co-culturing with non-EPS S. thermophilus . S. thermophilus 1275 was grown in skim milk in a Biostat B fermenterand samples were taken at 0, 6, 12, 18 and 24 h to determine the amountof EPS, and levels of lactic acid, lactose, glucose and galactose. The bac-terial count was also enumerated. EPS was isolated by protein removaland precipitation with ethanol and quantified using the phenol-sulphuricmethod. Lactic acid, lactose, glucose and galactose were determined us-ing HPLC. S. thermophilus 1275 produced 406 mg/L of EPS and 3.09 g/L of lacticacid at 37 o C. High temperatures and low pH reduced the EPS pro-duction, which ultimately ceased at pH 4.5. Maximal growth of theorganism and lactic acid production occurred at conditions different tothose for EPS production. The pH, temperature, WPC and co-culturingplayed an important role in the rate and the amount of EPS and lac-tic acid produced. EPS production peaked at pH 5.5 and at 37-40 o Creaching at 458mg/L. The EPS production was further stimulated byco-culturing with non-EPS S. thermophilus reaching at 832mg/L andthe highest lactic acid concentration of 31.41 g/L. EPS production washighest at 1029 mg/L with WPC supplementation at pH 5.5, however,lactic acid concentrations were lower with WPC supplementation. Sig-nificantly less lactic acid was produced when the pH was not controlledduring fermentation with or without WPC supplementation.EPS production can be increased by supplementation with WPC. WPCalso reduced the concentration of lactic acid. Co-culturing with non-EPS S. thermophilus significantly increased EPS production and mayprovide a more attractive means of increasing EPS production, therebyimproving textural and functional characteristics of dairy foods withoutthe use of additives. Key Words: Exopolysaccharides, Co-culturing, Nutrient supplementation W262 selection of prebiotics utilization from Lacto-bacillus acidophilus ATCC 43121 for synbiotics. E. Y. An* 1 ,S. Oh 2 , and S. H. Kim 1 , 1 Korea University, 2 Hnkuk Yakult Institute  . The number of food and other dietary products containing live Bifi-dobacterium and Lactobacillus bacteria has increased in recent years.In the large intestine, prebiotics, in addition to their selective effects onbifidobacteria and lactobacilli, have influenced many aspects of bowelfunction through fermentation. The selected synbiotic pairs of stimu-lated lactobacillus strains and oligosaccharide enhancing their growthwere studied to determine the effect of probiotics, prebiotics and synbi-otics. This research was investigated effective ability of  L. acidophilus ATCC 43121 bacteria on minimal media by ratio of adding prebioticswhich was used as substrates. Viable cell count of  L. acidophilus ATCC 43121 and pH of media were measured during twelve, twentyfour hours incubation at 37 with seven prebiotics which were of dif-ferent concentrations to increase the growth of  L. acidophilus ATCC43121 selectively. From this experiment results, the effect of prebioticswas signicantly(P < 0.05) higher in control media compared to mediaadding ratio of fructooligosaccharide, lactulose, raffinose of incubationfor twenty four hours. The addition ratio expansion of this three pre-biotics was increased consequently by strains growth but pH was de-creased. For this experiment response surface methodology to createthe right mix ratio which will maximize the bacteria’s vital energy byusing mix of selected three prebiotics and from this, the right mixtureratio was 36.5%, 0.00% and 63.5%. Key Words: Lactobacillus acidophilus , Prebiotics, Synbiotics W263 Factors affecting autoaggregation behavior of bifidobacteria. S. A. Ibrahim*, O. A. Hassan, C. W. Seo, Y. Murad,M. Worku, and G. Shahbazi, North Carolina A&T State University  . Recent evidence suggests that the addition of bifidobacteria as a dietaryadjunct or probiotic may have important health benefits. However,in order for these bacteria to manifest beneficial effects, they need toachieve an essential mass through aggregation. Consequently, the abil-ity of bifidobacteria to aggregate is a desirable property sought for usein commercial food preparations. The objective of this research was todetermine the effect of media composition and incubation temperatureson autoaggregation behavior of bifidobacteria. Another objective of thiswork was to determine the cell surface characteristics of bifidobacteriaas related to autoaggregation. Autoaggregation behavior of bifidobacte-ria was determined using different media (TPY, Wilkins-Chalgren and 360 J. Anim. Sci. Vol. 81, Suppl. 1/J. Dairy Sci. Vol. 86, Suppl. 1  mMRS) and incubation temperatures (34, 37, and 42 C). Autoaggrega-tion ability was measured as autoaggregation percentage. In this pro-cedure, overnight culture was shaken at different times (30, 60, 90, 120,and 150 min). After shaking, 2 ml of the upper suspension of the culturewas transferred to anther tube and the optical density (O.D.610nm) wasmeasured. Three types of autoaggregation behavior characterized thestrains: (1) autoaggregation sensitive (S) for strains that formed a pre-cipitate resulting in a clear solution, (2) autoaggregation resistant (R)for strains that produced consistent turbidity, and (3) autoaggregationmoderate (M) for strains that showed slight turbidity. Results on themedia composition showed that TPY broth increased the autoaggrega-tion behavior of the tested strains, whereas Wilkins-Chalgren and MRSreduced autoaggregation behavior. Calcium ions induced the autoag-gregation. Tween 20 and Tween 80 reduced autoaggregation behavior.Higher incubation temperature (42 C compared to 34 C) increased theability of strains to autoaggregate. Hydrophilic and electrostatic sur-face properties influence the autoaggregation behavior of bifidobacteria.Our data indicated that media selection; incubation temperature, andcalcium ions are important factors affecting autoaggregation behaviorof bifidobacteria. Autoaggregation should be considered when selectionof bifidobacteria for their specific use in commercial preparations. Key Words: Bifidobacteria, Autoaggregation W264 Screening and selection of acid and bile resis-tant Lactobacillus reuteri  . S. A. Ibrahim*, S. Ahmad, C. W. Seo,G. Shahbazi, M. M. Salameh, and M. Worku, North Carolina A&T State University  . Probiotic supplements are becoming increasingly popular in the UnitedStates and Europe. Although there are many different types of probi-otics, the most common live cultures found in yogurt products are L.bulgaricus , S. thermophilus , L. acidophilus , and bifidobacteria. In ad-dition to these beneficial cultures, some dairy industries are beginningto add Lactobacillus reuteri  to their products as a beneficial culture. L.reuteri  helps prevent and treat both viral and bacterial diarrhea enhanc-ing the body’s resistance to gastrointestinal disease. However, in orderto survive and colonize in the gastrointestinal tract, L. reuteri  needs toshow high tolerance to acid and bile salt. The purpose of this work wasto investigate the effect of acid and bile salt on the survival and growthof  L. reuteri  . Five strains (CF 2F, DSM 20016, MM 7, MM 2-3, and SD2112) of  L. reuteri  were used in this study. Cultures were inoculatedinto fresh MRS broth with various concentrations of bile salt (0.0, 0.1,0.2, 0.3, and 0.4%) and pH values (pH 2.0, 3.0 and 6.5). Samples werethen mixed well and incubated at 37 C for 48 hrs. Bacterial growth wasmonitored by measuring turbidity at 610 nm in a spectrophotometer atdifferent time intervals during the incubation period. Results showedthat a 0.3% bile salt concentration caused a significant reduction in thegrowth of all tested strains (P < 0.05). The survival of  L. reuteri  dif-fered significantly among tested strains; MM 2-3 showed significantlyhigher growth rates than the other tested strains over the 48 hr incu-bation period. At a 0.2% bile salt concentration, a significant growthreduction (P < 0.01) was observed for strains CF2 F and MM7. None of the tested strains survived low pH (2.00 and 3.00). The results suggestthat acid and bile tolerance is an important selection characteristic forthe use of  L. reuteri  cultures as a dietary additive. Key Words: Lactobacillus reuteri  , Acid and bile resistant W265 Fourier transform infrared (FTIR) spec-troscopy for rapid detection, identification, and enumera-tion of bacteria in foods. H. Yang, C. W. Seo, and S. A. Ibrahim*, North Carolina A&T State University  . The presence of microorganisms in food products has important rami-fications for safety, quality, regulations, and public health. Rapid andreliable methods are required for the detection of microorganism, es-pecially foodborne pathogens. The use of Fourier transform infrared(FTIR) spectroscopy and chemometrics (partial least square (PLS) re-gression and hierarchical cluster analysis (HCA)) for the rapid detection,identification, and enumeration of bacterial in cultures was investigated.In this study, gram-negative ( Escherichia coli  O157:H7 (H1730, F4546,Cider, E0019) and Salmonella typhimurium (ATCC 14208)) and gram-positive ( Lactobacillus reuteri  (SD2112, MM2-3, MM7, CF2-7F, MF14-C) were used. Pathogens were grown in brain heart infusion agar (BHI)whereas lactobacillus strains were grown in MRS broth. All strains wereincubated at 37 C for 24hr. FTIR spectrometer with attenuated total re-flectance (ATR) was used to measure aqueous microbial samples. Freshbroth without microorganism was used as background. The spectraldata collection was just taken about 3 minutes. Different spectral re-gions (3700 - 2800 cm − 1 and 1800 - 1000 cm − 1 ) were used to identifyand classify. Bacteria were clustered into negative (( E. coli  O157:H7, S.typhimurium ) and positive ( L. reuteri  ) groups while the rate of correctclassifications is 100%. HCA even demonstrated the differences amongH1730, F4546, Cider, E0019 strains of  E. coli  and SD2112, MM2-3,MM7, CF2-7F, MF14-C strains of  L. reuteri  , separately. A dendrogamindicated that CF2-7F was different from the rest of  L. reuteri  becauseit was found in the infant sample while the other were from adults. PLSregression was used for enumeration of bacteria. A R-square value was0.999 from PLS model based on spectral data and cell numbers. Our re-sults indicated that FTIR spectroscopy could be used as a rapid methodfor the identification and enumeration of bacteria in foods. Key Words: Fourier transform infrared (FTIR), Dairy foods, Pathogens W266 Encapsulation of  Lactobacillus reuteri  withsodium alginate for continuous production of lactic acid. S. A. Ibrahim*, C. W. Seo, S. Phetsomphou, and G. Shahbazi, NorthCarolina A&T State University  . Lactic acid fermentation is a well-known process used to preserve foodproducts. The most common approach in lactic acid fermentation isthe use of batch system. However with this process several factors limitefficiency of the production of lactic acid. For example, the end prod-ucts may cause an inhibitory effect on the lactic acid bacteria (LAB).Consequently an alternative method, one that does not have inhibitoryeffects on LAB is needed. A possible method that meets these challengesinvolves immobilization of LAB with sodium alginate. The objective of this research was to determine the ability of encapsulated Lactobacillusreuteri  ( L. reuteri  ) in sodium alginate to produce lactic acid. In thisstudy, the production of lactic acid was compared using two types of fer-mentation methods: Batch and batch bead fermentation. Six strains of  L. reuteri  , CF 2-F, DSM 20016, SD2112, MM 7, MF 14-C and MM 2-3were used. These strains were grown in lactobacillus MRS at 37C for 24hrs. The cells were then washed and suspended in 10-ml peptone water.Sodium alginate beads were prepared by resuspending the 10-ml culturein 7% sodium alginate solution. Beads were manufactured by droppingsodium alginate culture into ice-cold (2 C) 0.4M calcium chloride usinga separatory funnel. Under comparable conditions the sodium alginateencapsulated cells were allowed to ferment in 500-ml lactobacillus MRSand whey based medium at 37C for 24 hrs. Samples were withdrawnat two -hour intervals during storage period and analyzed for pH value,lactose, glucose, and lactic acid. Results showed that the pH reached4.00 within 15 hrs with beads fermentation and reached 5.40 using con-ventional batch. This indicates that higher acid yields can be producedusing bead fermentation. Strain MM 2-3 produced the highest lacticacid yield as measured by pH value (pH 3.70) and lactic acid (8.0%)while strain SD2112 produced the lowest acid yield as measured by pHvalue (pH 4.18) and lactic acid (2.0%) levels. Our results suggest thatusing immobilized cells of  L. reuteri  could have potential use to pro-duce lactic acid for commercial applications in food and pharmaceuticalindustries. Key Words: Lactobacillus reuteri  , immobilization W267 Antimicrobial activity of  Lactobacillus reuteri  against Escherichia coli  O157:H7. S. A. Ibrahim*, M. M.Salameh, W. M. Brown, G. Shahbazi, and C. W. Seo, North CarolinaA&T State University  . Lactobacillus reuteri  ( L. reuteri  ) is known to produce a broad-spectrumof antimicrobial compound, reuterin. The antimicrobial spectrum of reuterin includes Gram-positive and Gram-negative bacteria. The pur-pose of this study was to determine the antimicrobial activity of  L.reuteri  against the foodborne pathogen, Escherichia coli  O157:H7 ( E.coli O157:H7  ). Six different strains of  L. reuteri  (CF2-F, DSM 20016,MF14-6, MM2-3, MM-7) were incubated at 37C for 24 hrs in two differ-ent growth media (MRS without glycerol, and MRS with 0.2 M glycerolsolution). Samples were centrifuged (5,000g/15 min) to obtain super-natants (200 µ l) which were then tested against five strains of  E. coli  J. Anim. Sci. Vol. 81, Suppl. 1/J. Dairy Sci. Vol. 86, Suppl. 1 361  O157:H7 (944, 1730, Cider, E0019, F4546). E. coli  O157:H7 growthwas monitored by measuring turbidity at 610 nm in a spectrophotome-ter at different time intervals during incubation at 37 C for 8 hrs. Re-sults show that L. reuteri  has the ability to produce antimicrobial com-pound against E.coli  O157:H7 only in the presence of glycerol. Suchinhibition could not be observed when L. reuteri  was grown in MRSwithout glycerol. Two strains of  L. reuteri  showed total growth in-hibition against the foodborne pathogen. The growth inhibition couldbe observed within 4 hrs in LB broth. The growth inhibition was ob-served before the end of the exponential phase. The activity of  L. reuteri  against E. coli  O157:H7 was confirmed using agar diffusion assay. Theseresults suggest potential application of  L. reuteri  as a natural biopreser-vative to control growth of  E.coli  O157:H7 and ensure the safety of ourfoods. Key Words: Lactobacillus reuteri  , Escherichia coli  O157:H7 W268 Development of endospore-specific primersfor the analysis of microbial populations in milk powder. M. Arendts* 1 , C. Kitts 2 , and R. Jimenez-Flores 1 , 1 Cal Poly DPTC, 2 Cal Poly Biological Sciences  . A comprehensive risk assessment of the microbial quality of milk powdershould include information about endospores as well as viable bacteria. Bacillus endospores are present in raw milk, used in milk powder pro-duction, in numbers ranging from less than 10 to greater than 100 per gof solid. However, in the finished product they range from less than 1000to over 5x10 5 per gram, meaning that endospore-forming bacteria willhave the most significant effect on the microbial quality of the powder.Molecular methods offer a unique and sensitive tool for rapid micro-bial detection. Our focus is to apply polymerase chain reaction (PCR)methods to detect early germination of endospores in milk products.We have studied the germination gene, GerC3, from endospore-formingmembers of the family Bacillus . This led to the development of specificprimers for PCR detection. In the Dairy Products Technology Cen-ter (DPTC) endospore library, we have been able to detect five specificstrains that contribute to the lipolysis, casein hydrolysis, starch hy-drolysis, and acid production of milk products using our primers. Theprimers designed in this work identified either a 100bp or a 500bp ina conserved region of the GerC3 gene found in the five DPTC targetstrains. These bands have been detected during germination activity inall five of these Bacillus strains. Spore germination has been difficultto study because it involves extremely rapid physiological responses ina spore whose structure is biochemically intractable. We have evaluatedthe developed primers in Reverse Transcriptase- PCR (RT-PCR) in theearly detection of specific endospores present in skim milk powder re-sulting in the ability to document the presence or absence of endosporeforming bacteria. Results indicate that the rapid growth of endosporeforming bacteria can be monitored using RT-PCR. Key Words: Endospore detection, PCR, Milk powder W269 The effect of the incorporation of lactobacilliand whey protein isolate on the level of cell glutathionand immunoglobulin M(ig M). Y. H. Yoon* 1 and J. R. Byun, 1 Department of Animal Science and Technology, Chung-Ang Univer-sity  . The effect of the incorporation of whey protein isolates and Lactobacillusspp.in the mouse diet on the level of cell glutathion and Immuniglob-ulin M(Ig M) in the germ free ICR mouse feeding system.The studywas conducted to find out the effect of incorporation of Lactobacillusspp. on the cell gluthatione level and Ig M level in the spleen ,liverand erythrocyte cells. The highest and statistically significant level of glutathione in spleen cell has been shown in L.casei YIT 9018 cell fedgroup by feeding the diet containing 20% whey protein isolates amongthe 6 lactobacilli(p > 0.05). which was determined by the method utilyz-ing glutathione assay kit and the level of cell glutathione revealed to bestrain dependent. Providing with the L. casei YIT 9018 or L. acidophilusNCFM increased the level of liver glutathione level significantly. Andthe level of glutathione in erythrocite increased significantly by feed-ing the diet containing 20% whey protein isolate and with L. casei YIT9018 or L. casei CU 001(p > 0.05). Feeding L. casei YIT 9018 with wheyprotein isolate or L. acidophilus NCFM increased the Ig M level in thesplenocyte significantly which was determined by the method of plaqueforming unit counting. Key Words: Glutathione, Imminoglobulin M, Lactobacillus spp. W270 Evaluation of modified Elliker agar as an enu-meration medium for selected Lactic acid bacteria. D.Patel*, L. Goddik, K. Kido, and P. Elliker, Food Science and Technol-ogy, Oregon State University  . The objective of the project was to evaluate efficacy of Elliker agarmedium as a general purpose enumeration medium for lactic acid bac-teria. International Dairy Federation (IDF) recommends M17 agarfor starter lactococci and streptococci and MRS agar (DeMan RogosaSharpe) for starter lactobacilli enumeration. Current IDF protocol re-quires specific pH, incubation temperature and incubation conditions(e.g. anaerobic incubation) typical for specific starter bacteria. In lightof this the Elliker agar medium with specific modifications was utilizedto enumerate selected lactic acid bacteria as a convenient medium thatcan be used easily by the industry in a routine fashion.Lactic acid bacteria, namely S  treptococcus thermophilus ( ST), L actobacillus delbrueckii subsp. bulgaricus Y (LB), L actococcus lac-tis sub sp. lactis ATCC 11454 (LL) and L actobacillus acidophilus NCK1070 (LA) were utilized. All lactic acid bacteria were subcultured insterile skim milk. Experiments were repeated 3 times. Appropriatedilutions of skim milk cultures were pour plated as per IDF scheme.Additionally, Elliker medium was used in pour plating at comparablepH and a general pH 6.8 for all the comparisons. Elliker agar modifi-cations utilized alternative nitrogen sources such as casein hydrolysateand 3 per cent sterile skim milk. Based on the statistical analysis of data we found that modified Elliker medium gave similar recovery withregards to LA, LL, LB and ST when compared to M17 and MRS agar.It was also found that LB can be enumerated without anaerobic incu-bation when the purpose is general enumeration. pH had no significantinfluence in Elliker medium in regard to enumeration. Modified Ellikermedium appears to be a good candidate for general purpose enumerationmedia for lactic acid bacteria. Key Words: Lactic acid bacteria, International Dairy Federation, Fer-mented dairy foods W271 Effects of co-culturing EPS and non-EPSstarter cultures and supplementation with WPC on synere-sis, textural and rheological properties of set yoghurt. T.Amatayakul* 1 , B. Zisu 1 , F. Sherkat 2 , and N. P. Shah 1 , 1 Victoria Uni-versity, Melbourne, Australia, 2 RMIT University, Melbourne, Australia . Exopolysaccharide (EPS) producing starter cultures are becoming in-creasingly popular for use in the dairy industry. In our earlier study,EPS producing Streptococcus thermophilus 1275 when co-cultured withnon-EPS S. thermophilus produced higher levels of EPS. Supplementa-tion with WPC increased EPS production and reduced the rate of lacticacid production.The objective was to assess if these approaches could improve syneresis,textural and rheological properties of yoghurt.Six batches of yoghurts were made in triplicate using 12% reconstitutedskim milk (RSM) with or without replacement of RSM with 0.5% WPCand co-culturing with EPS and non-EPS starter culture (75:25). Synere-sis was determined as a percentage of whey expelled after centrifugation.A TA-XT2 texture analyser was used to measure textural propertiesand gel firmness, and rheological properties were determined by using aHaake Rheostress 50 rheometer. HPLC was used to measure the amountof lactic acid produced. EPS was quantified using the phenol-sulphuricmethod.Yoghurts made using EPS starters cultures showed reduced synere-sis. Control yoghurts made with non-EPS starter and without WPCshowed 65.20% syneresis, and those made using co-cultures 60.26%. Co-culturing and partial replacement with 0.5% WPC showed the highestreduction in syneresis at 52.37%. Control yoghurts had the hardest vis-cosity and hardness. Hardness and viscosity reduced in yoghurts con-taining EPS starter cultures, whereas WPC increased hardness and theviscosity was unaffected. In addition, yoghurts supplemented with WPCdid not show shear thinning behaviour. Yoghurts made with non-EPS S. thermophilus had the lowest shear stress regardless of supplementa-tion with WPC. Yield stress was lowest in control yoghurts at 248.70Pa. Co-culturing and WPC showed the highest yield stress at 363.367Pa. 362 J. Anim. Sci. Vol. 81, Suppl. 1/J. Dairy Sci. Vol. 86, Suppl. 1  Supplementation with WPC and co-culturing with EPS starters has asignificant effect (p < 0.05) on reduction of syneresis, textural and rheo-logical properties of set yoghurt, and may provide an alternative meansof improving functional characteristics of yoghurts without incorporat-ing the use of stabilizers. Key Words: Exopolysaccharides, Rheological properties, Yoghurt W272 Thermophilin 110: a broad spectrum bacte-riocin of  Streptococcus thermophilus . G. A. Somkuti* and D. H.Steinberg, Eastern Regional Research Center, ARS-USDA . A survey of thermophilic lactic starter cultures for bacteriocin produc-tion identified the broad spectrum antimicrobial peptide thermophilin110 of  Streptococcus thermophilus ST110, a strain used in yogurt andcheese fermentations. The range of bacteria inhibited by the bacteriocinincluded lactococci, lactobacilli and pediococci, in addition to relatedthermophilic streptococci. Production of thermophilin 110 at 37 o C par-alleled growth of  S. thermophilus ST110 in a tryptone-yeast extract-lactose medium. After 16 h of growth, bacteriocin titers reached 320units/ml by an agar well diffusion assay with Pediococcus acidilactici  asthe indicator strain. Thermophilin 110 was sensitive to digestion by pro-teolytic enzymes and lost its activity after a 60 min exposure to pepsin,pronase and papain. It was also inactivated by amylase treatment indi-cating glycosylation as a prerequisite for activity. Antimicrobial activitywas fully retained after heating crude thermophilin 110 preparations at80 o C for 60 min. Thermophilin 110 was acid resistant and remainedstable between pH 3 and 7 but lost its activity after exposure to pH10. Plasmid analysis of  S. thermophilus ST110 indicated the absence of plasmids, suggesting that the genetic determinant for thermophilin 110production is probably located on the chromosome. Inhibition of severalspecies of pediococci is a unique feature of thermophilin 110, implying apotential for applications in controlling the growth of spoilage bacteriain wine and beer fermentations. Key Words: Bacteriocin, Thermophilin 110, Streptococcus thermophilus W273 The influence of cold adaptation on cryotol-erance of  Bifidobacterium infantis . A. Gevorgyan* and R. F.Roberts, 1 The Pennsylvania State University  . The purpose of this study was to determine the influence of cold adap-tation on cryotolerance in Bifidobacterium infantis strain ATCC 15697and commercial strain BI-4. Growth of ATCC 15697 and BI-4 in Re-inforced Clostridial Broth (RCB) was determined at 20 ◦ C, 25 ◦ C, and37 ◦ C by measuring OD 600 . Overall BI-4 grew faster than ATCC 15697in RCB incubated at 37 ◦ C. Neither strain grew in RCB when incu-bated at 20 ◦ C or 25 ◦ C for up to 7 days. For cold shock experimentsand freeze-thaw challenge, cells were grown in 100 ml RCB at 37 ◦ Cuntil mid-log phase (OD 600 = 0.5) then 25 ml of culture was harvestedand resuspended in the same volume of tempered medium (20 ◦ C, 25 ◦ C,37 ◦ C). Ten ml of resuspended inoculum was transferred into two steriletubes and incubated at the designated temperatures for 240 min. Oneml samples were taken at 0, 30, 60, 120 and 240 min and frozen at -20 ◦ C for 24 hours, thawed for 10 min at 30 ◦ C, sampled for viable countand then re-frozen. The population of survivors was determined beforefreezing and after 1, 3, 6 and 9 freeze-thaw cycles by spread platingdecimal dilutions on RCA plates and incubating anaerobically at 37 ◦ Cfor 72h. Survivor data were normalized to the initial population (be-fore freezing). Experiments were replicated three times. When BI-4 wasincubated at 20 ◦ C or 25 ◦ C prior to freezing there was no change in pop-ulation after 9 freeze-thaw cycles. However when BI-4 was incubated at37 ◦ C for 60, 120, and 240 min the strain exhibited 0.5 log decrease inpopulation after 9 freeze-thaw cycles. Overall, ATCC 15697 was moresensitive to freeze-thaw challenge than BI-4. However, the loss of via-bility was reduced by incubating at 20 ◦ C or 25 ◦ C when compared to37 ◦ C, especially at incubation time of 120 and 240 min. Viable cells of ATCC 15697 could not be recovered after 6 freeze thaw cycles followingincubation at 37 ◦ C for 240 min. Viability of both strains after 9 freeze-thaw cycles decreased when incubated at 37 ◦ C for longer time (120 and240 min) suggesting cells in stationary phase are less cryotolerant. Incu-bation at suboptimal temperatures did not increase cryotolerance of  B.infantis and the effect of freeze-thaw challenge was strain dependent. Key Words: Probiotics, Bifidobacterium, Cryotolerance W274 Effect of c2 phage peptide on acid develop-ment in milk inoculated with Lactococcus lactis spp lactis C2 with and without c2 phage infection. I. Surjawan and C.L. Hicks*, University of Kentucky, Lexington, KY 40546  . Peptides from c2 phage were prepare by hydrolyzing c2bacteriophage(Φ) with ficin (0.2% at 26 ◦ C for 6 h). Inhibition of phage proliferation tests were conducted in milk following a rennetcheese schedule (1 h ripening at 31 ◦ C, rennet, cutting, cooking to 37 ◦ C,and holding at 37 ◦ C) by measuring change in pH during 4.5h of fer-mentation. Six sterilized pint jars were filled with 96 ml of pasteurizedmilk. Milks were inoculated (4%) with C2 culture that was grown inmedium with (2 jars) and without (3 jars) phage peptides (2%) added.One jar was inoculated with culture grown in medium containing 1% c2peptide. The milk in this jar also contained 1 % added c2 peptide. Oneof the milks that was inoculated with culture grown in medium withoutc2 peptide contained 2% added c2 peptide. Four of the milks wereinfected with c2 phage (10 3 pfu/ml). The pH decreased fastest in milkinoculated with C2 culture grown in medium without added c2 peptidethen in milk inoculated with culture grown in medium containing c2peptide. These 2 milks had significantly better acid production (pH5.63 and 5.71, respectively after 4.5 h of fermentation) than the other4 milks. However, milks that were inoculated with culture grown in c2peptide (both the 2% peptide medium and 1 % peptide medium with1% peptide added to the milk) and infected with (Φ)c2 did continue toproduce acid (pH 6.01) throughout the fermentation period. When 2%c2 peptide was added to the milk and inoculated with culture grown inmedium without peptide, acid development stopped (pH 6.23) after 200min. Acid production in milk inoculated with culture grown in mediumwithout peptide and infected with (Φ)c2 stopped (pH 6.25) after 120min of fermentation. These results suggest the culture grown in mediacontaining c2 peptide were protected from c2 phage proliferation andlysis during the fermentation period better than when the peptide wasadded to the milk, or when no peptide was present. Key Words: Lactococcus lactis , c2 Bacteriophage inhibition, pH Milk W275 Inhibition of  Salmonella  and Escherichia coli  phage with c2 phage peptide. C. L. Hicks, J. Tang, and I.Surjawan, University of Kentucky, Lexington, KY 40546  . Peptides from Lactococcus lactis Φc2 (phage) were prepared by hy-drolyzing Φc2 (10 9 pfu/ml) with ficin (0.2% at 26 ◦ C for 6 h). Hy-drolyzed peptide were partially purified by ultrafiltration (3000 mwco).Ultrafiltration permeate was dialyzed (500 mwco) and freeze dried, thenused to formulate growth media. Salmonella choleraesuis ssp. choler-aesuis (Smith) Weldin serotype Typhimurium deposited as Salmonella typhimurium (Loeffler) Castellani and Chalmers ATCC 14028 and Es-cherichia coli  (Migula) Castellani and Chalmers ATCC 47076 weregrown in 1558 medium and 1065LB medium, respectively, with and with-out Φc2 peptide present (various concentrations) and, with and withouttheir respective phage ( S. choleraesuis ssp. choleraesuis serotype Ty-phimurium phage ATCC 40282 and E. coli  lamda 97538 ). S. choler-aesuis ssp. choleraesuis grew faster when c2 peptide (1.5 and 2.5%concentrations) was added to the 1588 growth medium (incubated at37 ◦ C for 6 h). However, when ATCC 40282 phage was added to thegrowth medium (infected after 130 min incubation) with and withoutpeptides the media that contained 1.5 and 2.5% peptide had an extendedgrowth period of 21 and 28 min, respectively, before lysis occurred sug-gesting that c2 peptide had a minor inhibition effect on ATCC 40282phage proliferation. E. coli  also grew faster when the c2 peptide (2 and4% concentration) was added to the 1065LB growth medium. Howeverthe most rapid growth was present in the medium containing 2% pep-tide suggesting that peptide in the 4% medium was starting to blockmetabolic transport. When the lambda 97538 phage was added to thegrowth medium (infected after 90 min of incubation) only a slight inhi-bition of phage proliferation occurred in the 2% c2 peptide medium (20min) whereas in the 4% peptide medium phage proliferation was sup-pressed by 120 min suggesting that c2 peptide was an effective inhibitorof lambda 97538 phage proliferation. Key Words: Salmonella  , Bacteriophage inhibition, c2 phage-peptide J. Anim. Sci. Vol. 81, Suppl. 1/J. Dairy Sci. Vol. 86, Suppl. 1 363
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