Survivability of Bovine Derived Escherichia coli Subjected to Temperatures Typical of Summer in Texas

Transcription

1 The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 19 Survivility of Bovine Derived Escherichi coli Sujected to Tempertures Typicl of Summer in Texs Wyne Becker 1 Institute of Applied Science, Deprtment of Biologicl Sciences, University of North Texs, Denton, Texs 76203, USA Tmilee D. Nennich 1 Stephenville Reserch nd Extension Center, Texs A&M University, Stephenville, Texs 76401, USA Smuel F. Atkinson Institute of Applied Science, Deprtment of Biologicl Sciences, University of North Texs, Denton, Texs 76203, USA ABSTRACT Diry mnure nd wstewter is often stored in lgoons nd pplied to fields during summer months. The ojective of this study ws to determine the effect of moderte durtions of typicl Texs summer tempertures on the survivility of E. coli in diry mnure. Mnure smples were collected from two diry opertions nd ssigned to one of three temperture tretments, 73 F, 95 F, or 111 F. Mnure smples were nlyzed for E. coli on d 0, d 10, nd d 21. By d 10, E. coli levels in mnure smples were reduced (P < 0.01) from 5.34 log CFU/g t d 0 to 4.55 nd 0.25 log CFU/g in mnure smples stored t 95 F nd 111 F, respectively. All smples showed significnt (P < 0.001) reductions in E. coli popultions fter 21 d. On d 21, E. coli cteri in mnure stored t 111 F were undetectle, nd E. coli concentrtions verged 0.32 nd 3.69 log CFU/g for the 95 F nd 73 F tretments, respectively. Survivility of ovine derived E. coli ws reduced y tempertures tht re typicl of summer in Texs. Appliction of mnure during periods of high environmentl tempertures my fcilitte quicker decline in E. coli concentrtions s compred to ppliction during cool mient tempertures. KEY WORDS: Escherichi coli, diry, mnure, temperture INTRODUCTION Escherichi coli re type of cteri well dpted for survivl in nturl environments. These cteri re nturlly widely distriuted in soils nd odies of wter throughout the world, nd they re commonly found in the intestines of nimls nd humns. There re concerns tht pthogenic strins of E. coli from livestock mnure could move into surfce or groundwter nd pose risks to humn helth. The uthors would like to express their thnks to the Texs Animl Nutrition Council for their ssistnce in funding this study. 1 Current ddress: Deprtment of Animl Sciences, Purdue University, West Lfyette, Indin 47907, USA

2 The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 20 Reports hve shown tht tempertures ove 100 F decrese the concentrtions of E. coli in mnure (Hess et l., 2004; Michel et l., 2005). Hess et l. (2004) reported in composting study, where mnure nd strw were mixed in 20:1 C:N rtio t 70% moisture, tht tempertures s low s 104 ºF reduced the numers of E. coli 0157:H7. Similr tempertures hve lso een shown to eliminte ll strins of E. coli cteri during the process of eroic digestion (Michel et l., 2005). Escherichi coli popultions do not multiply rpidly under cool tempertures. Tempertures of 46.4 ºF hve een shown to initilly foster the growth of certin E. coli strins, ut cused them to decline in susequent dys (Frncis nd O Beirne, 2001). Tempertures of 39.2 ºF hve een shown to reduce, ut not eliminte, the growth of E. coli (Frncis nd O Beirne, 2001). Furthermore, E. coli hs the ility to reproduce exponentilly s n initil response to exposure to tempertures etween 73 ºF nd 77 ºF (Fujiok nd Byppnhlli, 1998). The time of yer of mnure ppliction hs een shown to hve n effect on cteril popultions (Miller et l., 2003; Shrples et l., 2004). A Cndin study concluded lnd ppliction of mnure in spring or fll ws preferle to pplictions in summer due to the fct tht E. coli nd totl coliform popultions were found to e significntly greter s summer ir tempertures incresed to 81 ºF (Miller et l., 2003). A study y Shrples et l. (2004) found tht mnure pplied in June resulted in greter survivl rtes of E. coli s opposed to mnure pplied in August, nd Fukushim et l. (1999) noted decresed persistence of E. coli in mnure t tempertures of 77 ºF. In Texs, diry wste is often stored in lgoons nd pplied to fields during the summer months. During the summer, ir tempertures in Texs cn esily exceed 100 ºF nd soil tempertures typiclly rech 86 ºF (ARS, 2009). As result of high tempertures tht re common during the summer, E. coli concentrtions of mnure my decline more rpidly thn would e expected in more moderte climte. The ojective of this study ws to determine the effect of moderte durtions of typicl Texs summer tempertures on the survivility of E. coli in diry mnure. MATERIALS AND METHODS Mnure smples for this study were collected from 2 different diry opertions, P nd F. The diry opertions were locted pproximtely 20 miles prt nd were oth in Cooke County, TX. The diry opertions used different mngement styles nd feeding prctices. Diry P ws 150 cow dry-lot diry tht utilized totl mixed rtion with feeding lne, nd diry F ws 90 cow grzing-sed diry tht fed supplementl grin inside the milking prlor nd fed some supplementl silge. Mnure ws collected t ech diry from the holding pen outside of the milking prlor. Smple Collection nd Tretments. The mnure for the study ws collected from the milking prlor holding pens t ech diry within 2 hours of completion of morning milking. Mnure ws mnully collected nd compiled from the holding pen with scrper. After collection, mnure ws thoroughly mixed. Approximtely 210 qt of mnure were collected from ech diry nd used to fill nine seprte 24 qt plstic continers with lids. Ech continer ws filled with ~23 qt of mnure. The mnure ws then immeditely trnsported to temperture controlled storge; reching storge within 3 hours fter collection.

3 The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 21 After rrivl t the storge loction, six mnure smples, three composite smples from ech diry, were collected nd sumitted for nlysis to determine E. coli levels t the initition of the tril period. The initil smples were used s the seline E. coli concentrtions (d 0). The continers from oth diry F nd diry P were seprted into three groups of three replictes ech. Ech group of replictes from the two diries ws ssigned to one of three temperture tretments. The control tretment ws set t room temperture of 73 F. The second tretment ws stored t 95 F, nd the third tretment ws sujected to greter temperture of 111 F. Mnure smples were stored t their respective ssigned tretments within 3 hours of collection, where they were held for 21 dys. Continers for ech replicte were 24 qt plstic storge oxes, with loose fitting lids to llow for venting of gses. Room temperture replictes were stored in n ir conditioned lortory, nd medium nd high temperture replictes were stored in lrge, electric temperture-controlled incutors. Individul continers were stored t the sme temperture throughout the study. On d 10 nd d 21, ech mnure continer ws opened nd thoroughly mixed. After mixing, 8 oz of mnure from ech continer ws collected nd sumitted for nlysis. Smple Anlysis. All nlysis of mnure ws done y Midwest Ls in Omh, Nersk. After collection, mnure smples were immeditely cooled to 39 F. The 8 oz mnure smples were pcked in temperture controlled continers nd sent next-dy delivery to insure tht smples were ville for nlysis within 24 h of collection. Mnure smples were nlyzed for E. coli with 3M Petrifilm E. coli/coliform count pltes (AOAC Officil Method ; 3M Microiology Products, St. Pul, MN) using 25 g of mnure. A composite smple from ech diry ws nlyzed t the end of the study to determine the nutrient content of the mnure. Smples collected during the initil mnure collection were lso used to test for the presence of E. coli O157: H7. Mnure smples (25 g) were nlyzed using the RpidCheck E. coli O157 Test Kit (Prt Numer nd Prt Numer ; Strtegic Dignotics, Inc., Newrk, DE) to determine the presence of E. coli O157:H7. Sttisticl Anlysis. The study ws rrnged in 2 x 3 fctoril design with repeted mesures. Numers of E. coli were mesured in colony forming units (CFU)/g. These popultions were trnsformed using logrithms to chieve norml distriutions. The dt were nlyzed using the Proc Mixed procedure of SAS (SAS Institute, 2004). The simple covrince structure resulted in the lowest Byesin Informtion Criterion nd ws used s the covrince structure. The repeted sttement ws included to nlyze the differences over time. Differences were declred significnt when P < 0.05, s determined y the lest squres mens test. Sttisticl nlysis of cteri popultions is reported in logrithmic form. RESULTS Initil physicl chrcteristics of the mnure from the two diry opertions ppered to differ t the time of collection. Mnure from diry F ppered to e drier, more firous, nd hd visile signs of whole grin sorghum in the mnure. Mnure from diry P ppered to hve greter moisture content, possily due to the wter sprinkler

4 The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 22 system tht ws in use in the cttle holding pen for cow cooling t diry P. Moisture nd nutrient nlysis of the mnure smples t the end of the study re shown in Tle 1. Averge concentrtions of E. coli t the strt of the study were 5.53 log CFU/g for diry F nd 5.14 CFU/g for diry P. The initil mnure smples from diries F nd P were nlyzed for the presence of E. coli O157:H7. Anlysis for E. coli O157:H7 in the mnure smples did not return ny positive results, with E. coli O157:H7 concentrtions elow the detection limit of 0.04 cells/g for the mnure smples from ech of the diries. Tle 1. Moisture nd nutrient composition of mnure smples from diry P nd diry F. Prmeter Diry P Diry F Totl Solids, % DM Bsis Ash, % Totl Nitrogen, % Ammonium Nitrogen, % Orgnic Nitrogen, % Phosphorus, % Potssium, % ph The differences etween the tretments t ech smpling dte for diry F nd diry P re shown in Tles 2 nd 3, respectively. On d 10, E. coli concentrtions in the mnure from diry F stored t 95 ºF were significntly less thn E. coli concentrtions in the mnure stored t 73 F. However, E. coli concentrtions in the mnure stored t 73 F from diry F ctully incresed s compred to concentrtions t the strt of the study, wheres there ws slight decrese in E. coli concentrtions for the 73 F tretment on d 10 for diry P. Tle 2. Concentrtions of E. coli (log CFU/grm) of mnure smples t diry F. Tretment Dy * 73 ºF 95 ºF 111 ºF SE ND c ND 0.28 * Differing superscripts within row indicte significnt differences (P < 0.05). ND E. coli were elow detectle levels (< 0.3 log CFU/g). Tle 3. Concentrtions of E. coli (log CFU/grm) of mnure smples t diry P. Tretment Dy * 73 ºF 95 ºF 111 ºF SE ND ND 0.28 * Differing superscripts within row indicte significnt differences (P < 0.05). ND E. coli were elow detectle levels (< 0.3 log CFU/g).

5 E. coli, log(10) CFU per g The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 23 In this study, E. coli concentrtions of mnure stored t 111 F declined significntly more quickly thn mnure stored t either 73 F or 95 F. By d 10, E. coli ws only detectle in one replicte from diry P, nd the concentrtion in tht smple ws 1.52 CFU/g. At d 21, E. coli ws not detectle in ny of the smples stored t 111 F. In contrst, E. coli ws still present in ll of the mnure smples stored t 73 F. However, even the smples stored t 73 F showed significnt decline in the concentrtions of E. coli over the 21 d period (Figure 1). DISCUSSION The lower concentrtions of E. coli in mnure t diry P were prtilly ccounted for y the difference in moisture concentrtion etween the two frms. The differences in the mnure nutrient, moisture, nd cteri concentrtions were most likely result of the different mngement styles of the two diry opertions, s dietry feed ingredients, housing, nd niml mngement vried etween the two diry opertions. Overll, the E. coli concentrtions in the fresh mnure smples were similr to previously reported vlues s Mels nd Brun (2006) reported E. coli concentrtions verging 5.7 CFU of E. coli/g of wet diry mnure for smples collected in June in Vermont. The vrying moisture or nutrient content of the mnure from the two diries my hve plyed roll in the greter sustined growth of E. coli in the mnure from diry F stored t 73 F degrees F 95 degrees F 111 degrees F Figure 1. Averge concentrtions of E. coli in diry mnure from two diry opertions on dy 0, dy 10, nd dy 21 when held t vrious tempertures. Dy of Smpling: Dy, Dy 10 ( ), nd Dy 21 ( ). *ND - E. coli were elow detectle levels (< 0.3 log CFU/g) t dy 21. c Brs with different letters t given temperture indicte significnce t P < c ND* With incresed time nd/or incresed het, the survivility of E. coli decresed significntly in this study. When the temperture of the mnure ws held t 111 ºF, E. coli concentrtions in mnure declined quickly nd were not detectle in most of the mnure smples within 10 d. The decline in E. coli t 73 ºF occurred without exposure to solr rdition or drying effects tht would e expected in nturl environment. When

6 The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 24 the storge temperture of mnure incresed, the mortlity rte of E. coli incresed significntly. Escherichi coli O157:H7 is the strin implicted in most humn helth concerns. In this study, E. coli O157:H7 ws elow the detection limit of the ssy nd ws not detected in the mnure smples. According to Vinten et l. (2002), E. coli O157 ppers to e equl to or more susceptile to environmentl stress thn generic E. coli nd less likely to e present in runoff from lnd where griculture slurry my e pplied. The Environmentl Protection Agency uses generic E. coli cteri s the criteri to determine when the levels of fecl contmintion in surfce wters need to e ddressed, regrdless of the strin of E. coli present. Animl derived E. coli survivility is dependent on the environment in which it must reside. This study concludes tht tempertures of 95 F nd 111 F will crete conditions tht increse the mortlity rte of E. coli cteri found in diry mnure. Since ir tempertures in summer months in Texs commonly exceed 100 F (ARS, 2009), summer ir tempertures would ssist in reducing concentrtions of E. coli in diry mnure. Recommendtions for mnure mngement prctices concerning the timing of the ppliction of diry mnure to croplnd or psture in Texs my need to e revisited. In Texs or other res with hot climtes where E. coli is concern, ppliction of mnure when mient tempertures re t the gretest my e mngement prctice tht fcilittes reductions in E. coli concentrtions. Recommendtions for mnure ppliction during high tempertures re in contrst to pst studies (Miller et l., 2003) tht imply cooler tempertures will reduce the rte of E. coli multipliction. Elevted ir tempertures, long with solr rdition (LeJeune et l., 2001; Berney et l., 2006), my reduce E. coli popultions in mnure, therey reducing the mount of vile E. coli tht could e trnsported to nery wter sources. The results of this study indicte recommendtions for mnure ppliction should e sed on the climte of the ppliction loction. REFERENCES ARS (Agriculture Reserch Service), Reisel Reserch Center Online. Aville: Berney, M., H. Weilenmnn, J. Ihssen, C. Bssin, nd T. Egli Specific growth rte determines the sensitivity of Escherichi coli to therml, UVA, nd solr disinfection. Appl. Environ. Biol. 72: Frncis, G. A., nd D. O Beirne Effects of vegetle type, pckge tmosphere nd storge temperture on growth nd survivl of Escherichi coli O157:H7 nd Listeri monocytogenes. J. Ind. Microiol. Biotechnol. 27: Fujiok, R. S., nd M. N. Byppnhlli Do fecl indictor cteri multiply in the soil environments of Hwii? Finl report to USEPA. Pges WRRC 98-04, Wter Resources Reserch Center, University of Hwii. Fukushim, H., K. Hoshin, nd M. Gomyod Long-term survivl of shig toxin producing Escherichi coli O26, O111, nd O157 in ovine feces. Appl. Environ. Microiol. 65: Hess, T. F., I. Grdzelishvili, S. Higing, nd C. J. Hovde Het inctivtion of E. coli during mnure composting. Compost Sci. Util. 12: LeJeune, J. T., T. E. Besser, N. L. Merrill, D. H. Rice, nd D. D. Hncock Livestock drinking wter microiology nd the fctors influencing the qulity of

7 The Texs Journl of Agriculture nd Nturl Resource 23:19-25(2010) 25 drinking wter offered to cttle. J. Diry Sci. 84: Mels, D. W., nd D. C. Brun Demonstrtion of methods to reduce E. coli runoff from diry mnure ppliction sites. J. Environ. Qul. 35: Michel, Jr., F. C., S.K. Grewl, S. Rjeev, nd S. Sreevtsn Persistence of microil pthogens during composting liquid storge nd pck storge of diry nd swine mnure. NCSU Wste Symposium. Online. Aville: Miller, J. J., B. W. Besley, L. J. Ynke, F. J. Lrney, T. A. McAllister, B. M. Olson, L. B. Selinger, D. S. Chnsyk, nd P. Hsselck Bedding nd sesonl effects on chemicl nd cteril properties of feedlot cttle mnure. J. Environ. Qul. 32: SAS Institute SAS/STAT User s Guide: Sttistics, Version 9.1. SAS Inst., Inc., Cry, NC. Shrples, K. E., G. W. Strtton, S. A. Mdni, R. J. Gordon, nd G. Ptterson The survivl of E. coli in griculturl soil treted with diry mnure. Pper numer Americn Society of Agriculturl nd Biologicl Engineers. St. Joseph MI. Vinten, A. J. A., D. R. Lewis, D. R. Fenlon, K. A. Lech, R. Howrd, I. Svood, nd I. Ogden Fte of Escherichi coli nd Escherichi coli O157 in soils nd dringe wter following cttle slurry ppliction t 3 sites in southern Scotlnd. Soil Use Mnge. 18: