Chicken Feces Research Articles

Quality Characteristics of Livestock Feces Composts Commercially Produced in Gyeonggi Province in 2008

This survey was conducted to promote the environment-friendly use and recycling of livestock feces by obtaining information about the current state of livestock feces composts manufactured in Gyeonggi Province. Therefore, some aspects of quality and manufacturing techniques of livestock feces composts (LFCs) were examined especially in relation to the LFCs quality standard (LQS). By surveying the 70 composting plants in Gyeonggi Province, the total commercial production of LFCs in 2008 was estimated to be about <TEX>$480,000Mg\;year^{-1}$</TEX> and they were manufactured mainly by using both mechanical mixer and bottom air blower. LFCs were composed mainly of chicken feces 29.2%, pig+chicken feces 23.1%, pig feces 20.0%, livestock feces+oil cake 12.3%, pig+chicken+cattle feces 10.8% and pig+cattle feces 4.6%. On the basis of the current official standard which was revised on March 2010, 11 composts out of surveyed 76 ones did not meet the LQS due to inadequate content of water (5), OM/N (1), NaCl (2) and Zn (3). The satisfaction rate to LQS by manufacturers was 100% in the composts produced by farmer's cooperative societies, 80.7% by civil factories, and 44.4% by farming guilds, respectively. The OM/N declined by adding chicken feces and oil cake, while Ca content was increased by the addition of chicken feces and NaCl was increased by adding cattle feces.

Multidrug-Resistant Enterococci in Animal Meat and Faeces and Co-Transfer of Resistance from an Enterococcus durans to a Human Enterococcus faecium

Forty-eight isolates resistant to at least two antibiotics were selected from 53 antibiotic-resistant enterococci from chicken and pig meat and faeces and analysed for specific resistance determinants. Of the 48 multidrug-resistant (MDR) strains, 31 were resistant to two antibiotics (29 to erythromycin and tetracycline, 1 to erythromycin and vancomycin, 1 to vancomycin and tetracycline), 14 to three (erythromycin, tetracycline and vancomycin or ampicillin) and 3 to four (erythromycin, vancomycin, ampicillin and gentamicin). erm(B), tet(M), vanA and aac (6')-Ie aph (2'')-Ia were the antibiotic resistance genes most frequently detected. All 48 MDR enterococci were susceptible to linezolid and daptomycin. Enterococcus faecalis (16), Enterococcus faecium (8), Enterococcus mundtii (2) and Enterococcus gallinarum (1) were identified in meat, and E. faecium (13) and Enterococcus durans (13) in faeces. Clonal spread was not detected, suggesting a large role of gene transfer in the dissemination of antibiotic resistance. Conjugative transfer of resistance genes was more successful when donors were enterococcal strains isolated from faeces; co-transfer of vanA and erm(B) to a human E. faecium occurred from both E. faecium and E. durans pig faecal strains. These data show that multidrug resistance can be found in food and animal species other than E. faecium and E. faecalis, and that these species can efficiently transfer antibiotic resistance to human strains in inter-specific matings. In particular, the occurrence of MDR E. durans in the animal reservoir could have a role in the emergence of human enterococcal infections difficult to eradicate with antibiotics.

Detection of Integrons from Escherichia coli Isolates Obtained from Some Selected Animals in Republic of Korea

We detected integrons in 298 of 1106 Escherichia coli isolates obtained from the feces of pigs, chicken, ducks and elks. Among the sources there was higher number of integrons detected in the isolates of pigs. No integron was found in the isolates of gooses. Detection of lot of integrons in these isolates discovers the possibility of spread of antibiotic resistance genes in the environment.

Detection of Arcobacter in feces of healthy chickens in Osogbo, Nigeria.

Isolation of arcobacters in foods, with the highest prevalence reported in poultry, has underscored its importance as a potential food safety problem in recent years. To estimate its prevalence in live birds, fresh stool samples from healthy chickens were screened by enrichment and plating on Arcobacter selective medium containing cefoperazone, amphotericin B, and teicoplanin. Of 150 fecal samples, only 2 (1.3%) yielded Arcobacter. Species were identified with fluorescence resonance energy transfer PCR. Isolate no. 21 from a local flock shared 99% identity with the complete genome of A. butzleri RM4018 (CP000361.1). Isolate no. 4 from a layer hen shared 100% identity with a partial 16S rRNA gene sequence of A. cryaerophilus (EF064151.1). The low prevalence of Arcobacter in the fecal samples of healthy chickens concurs with earlier studies suggesting that Arcobacter appears to be a transient colonizer of poultry intestines and therefore might not be the major source of chicken carcass contamination.

Study on Characteristics of a Strain of Penicillium sp. Capable of Heterotrophic Ammonium Oxidation

An ammonia-oxidizing strain of Penicillium sp., M25-22 which was isolated from chicken feces compost, was studied to make clear its characteristics of ammonium oxidation and provide References for its application in aerobic composting. In media containing (NH 4) 2SO 4 at a concentration of 0.5 g 100 mL -1, mycelium weight and utilization ratio of ammonium nitrogen increased markedly during the 1st 5 d, concentration of nitrate increased markedly from the 3rd to the 5th d and concentration of nitrite remained at a low level. The strain showed the ability to oxidize ammonium nitrogen growing in media containing glucose, sucrose, starch, or cellulose as the sole carbon source and to oxidize the negative trivalent nitrogen of ammonium sulfate, peptone, acetamide, urea, or L-aspartate. Slowly available carbon or nitrogen sources such as starch, cellulose, and peptone were beneficial to ammonium oxidation. In media containing sucrose as the sole carbon source and ammonium sulfate as the sole nitrogen source, nitrate formation was the most pronounced with sucrose present at a concentration of 12 g L -1 and ammonium nitrogen present at a concentration of 2.438 mg mL -1, at the initial pH level of 7.5 and at 30°C.

Microfluidic immunosensor with integrated liquid core waveguides for sensitive Mie scattering detection of avian influenza antigens in a real biological matrix

This work presents the use of integrated, liquid core, optical waveguides for measuring immunoagglutination-induced light scattering in a microfluidic device, towards rapid and sensitive detection of avian influenza (AI) viral antigens in a real biological matrix (chicken feces). Mie scattering simulations were performed and tested to optimize the scattering efficiency of the device through proper scatter angle waveguide geometry. The detection limit is demonstrated to be 1 pg mL(-1) in both clean buffer and real biological matrix. This low detection limit is made possible through on-chip diffusional mixing of AI target antigens and high acid content microparticle assay reagents, coupled with real-time monitoring of immunoagglutination-induced forward Mie scattering via high refractive index liquid core optical waveguides in close proximity (100 μm) to the sample chamber. The detection time for the assay is <2 min. This device could easily be modified to detect trace levels of any biological molecules that antibodies are available for, moving towards a robust platform for point-of-care disease diagnostics.

Seasonal variations in the prevalence ofCryptococcus neoformansvar.grubiiandCryptococcus gattiiin decayed wood inside trunk hollows of diverse tree species in north-western India: a retrospective study

This study presents a 7-year retrospective analysis of seasonal variations in the prevalence of Cryptococcus neoformans var. grubii and Cryptococcus gattii in decayed wood inside trunk hollows of 518 trees belonging to 20 species in north-western India during 2000-2007. Of the 1,439 wood samples investigated, 406 (28.2%) were found to be positive for the Cryptococcus neoformans species complex which included 247 samples from which C. neoformans var. grubii was recovered and 171 which yielded C. gattii. While both of the pathogens were isolated through all the seasons, the overall prevalence of C. neoformans var. grubii was significantly higher (17.2%) than that of C. gattii serotype B (11.9%, P < 0.0001), indicating that decayed wood was as good, if not better, a natural habitat of C. neoformans var. grubii as that of C. gattii. The highest recovery of both yeasts was in the autumn, followed by that in the summer. For C. gattii, the lowest prevalence occurred during the winter and for C. neoformans var. grubii during the rainy season. The low prevalence of C. gattii during winter is similar to that reported from Bogota, Colombia, where C. gattii had a low population density in bark samples but it was not found in decayed wood of trunk hollows investigated during the period of January and February. The prevalence of C. neoformans var. grubii was significantly lower in the rainy season than in the other portions of the year. This finding is similar to the reported low isolation frequency (4%) of C. neoformans var. grubii from chicken feces in the rainy season in northern Thailand. Further investigations are warranted to determine the clinical significance of seasonal variations in the prevalence of C. neoformans var. grubii and C. gattii in decayed trunk wood of various trees in climatically divergent regions of India.

Molecular and virulence characteristics of multi-drug resistant Salmonella Enteritidis strains isolated from poultry

Forty-six Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) strains were isolated from chicken meat, faeces, and eggshells collected from hatcheries throughout Korea. The strains were examined for the presence of antimicrobial resistance and virulence genes. All 46 isolates were resistant to at least one of 21 antibiotics used in this study, 30 (65.2%) were resistant to three or more antimicrobials, and a single remarkable isolate was resistant to 15 antimicrobials. The isolates were primarily resistant to penicillins, sulfisoxazole, streptomycin, tetracycline and quinolones. The high rate of resistance in S. Enteritidis strains, sometimes to multiple drugs, may complicate future options for treating human infections. Nineteen of the 21 penicillin resistant isolates carried the bla(TEM) gene, while one strain, resistant both to penicillins and ceftriaxone, carried the bla(CTX-M) gene. Thirty-seven of the 45 sulfisoxazole resistant isolates carried sul2, and 23/24 streptomycin resistant isolates carried both strA and strB. All 10 tetracycline resistant isolates carried the tet(A) gene. Most isolates harboured both SPI-1 and SPI-2-associated genes, and the spv operon, which are known to be associated with human infections. The presence of these genes suggests that these strains could give rise to public health problems if dispersed in the general human population.

Screening of Immunostimulatory Probiotic Lactic Acid Bacteria from Chicken Feces as Animal Probiotics

The principal objective of this study was to screen and select acid-tolerant Lactobacillus strains from chicken feces, feeds, and other sources. Fourty six strains evidencing acid tolerance (pH 3.5) were isolated in this study. Among them, nine strains exhibited marked immunostimulatory effects. Therefore, nine candidate strains were characterized for probiotic use. In order to evaluate macrophage activation, NO production was measured using RAW 264.7 cells. In particular, three strains (FC812, FC222, and FC113) evidenced the highest levels of NO production measured at 38.39±20.01, 35.06±27.73, and 33.88±15.99 ?M, respectively, at a concentration of 108 CFU/mL. The majority of strains, with the exception of strain FC322, evidenced marked resistance to artificial gastric juice (pH 2.5 with 1%(w/v) pepsin). Additionally, strains FC222, FC421, FC511, and FC721 were highly resistant to artificial bile acid (0.1%(w/v) oxgall), whereas strains FC113, FC322, FC422, FC621, and FC812 were the least resistant to bile. All nine strains exerted antimicrobial effects against chickenrelated pathogens. Additionally, all nine strains were found to be resistant to several antibiotics. The isolated strains, except for strain FC322, were tentatively identified as Lactobacillus salivarius, using an API 50 CHL kit. These results demonstrate that some probiotic organisms may potentially probiotic properties, and thus may serve as an effective alternative to antibiotics in animal applications.

Analysis of whole cell protein profiles of Salmonella serovars isolated from chicken, turkey and sheep faeces by SDS-PAGE

This study was carried out to determine the whole cell protein profiles of Salmonella serovars from chicken, turkey and sheep faeces by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A total of 34 Salmonella strains were included in the study, 14 of them were isolated from chicken, 14 from turkey and six from sheep. SDS-PAGE was carried out using 12% (w/v) separating and 4% (w/v) stacking gels. The results showed more than 30 protein bands ranging in size from 97 kDa (kilodaltons) to below 14.4 kDa as determined by visual assessment of their approximate molecular masses. Protein bands of 78.1, 51.2, 41.5, 37.3, 35.1, 33.9, 30.7, 27.6, 25.4, and 24 kDa were detected in all Salmonella serovars. Salmonella strains used in this study were closely related and could not be differentiated depending on the whole cell protein profiles using SDS-PAGE.

Medium Optimization for the Production of Probiotic Lactobacillus acidophilus A12 Using Response Surface Methodology

Lactobacillus acidophilus A12 was isolated from chicken feces for use as an immunostimulating livestock probiotic. The purpose of this study was to optimize the production of L. acidophilus A12 using response surface methodology (RSM). Initially, the influence of growth medium was studied in terms of carbon sources (glucose, fructose, lactose, glycerol, sucrose, ethanol, and mannitol), nitrogen sources (beef extract, yeast extract, malt extract, and tryptone), and inorganic salts (CaCl , MgSO , KH PO , (NH ) SO , FeSO , and NaCl). Through one factor-at-a time experiment, lactose, yeast extract, and CaCl were determined to be the best sources of carbon, nitrogen, and inorganic salt, respectively. The optimum composition was found to be 17.7 g/L lactose, 18.6 g/L yeast extract, and 0.9 g/L CaCl . Under these conditions, a maximum cell density of 9.33 Log CFU/mL was produced, similar to the predicted value.

Estimated human health risks from exposure to recreational waters impacted by human and non-human sources of faecal contamination

This work was conducted to determine whether estimated risks following exposure to recreational waters impacted by gull, chicken, pig, or cattle faecal contamination are substantially different than those associated with waters impacted by human sources such as treated wastewater. Previously published Quantitative Microbial Risk Assessment (QMRA) methods were employed and extended to meet these objectives. Health outcomes used in the analyses were infection from reference waterborne pathogens via ingestion during recreation and subsequent gastrointestinal (GI) illness. Illness risks from these pathogens were calculated for exposure to faecally contaminated recreational water at the U.S. regulatory limits of 35 cfu 100 mL −1 enterococci and 126 cfu 100 mL −1 Escherichia coli. The probabilities of GI illness were calculated using pathogen dose-response relationships from the literature and Monte Carlo simulations. Three scenarios were simulated, representing a range of feasible interpretations of the available data. The primary findings are that: 1) GI illness risks associated with exposure to recreational waters impacted by fresh cattle faeces may not be substantially different from waters impacted by human sources; and 2) the risks associated with exposure to recreational waters impacted by fresh gull, chicken, or pig faeces appear substantially lower than waters impacted by human sources. These results suggest that careful consideration may be needed in the future for the management of recreational waters not impacted by human sources.

Calcium and phosphorus contents of body parts of some domestic animals used as meat source in Nigeria

Objective To investigate the calcium and phosphorus contents of four domestic animals used as sources of meat in Nigeria. Methods The calcium contents of the body parts of the animals were determined using atomic absorption spectrometer. Their phosphorus contents were determined colorimetrically using the molybdenum blue method. Results The calcium and phosphorus contents were significantly higher in the bone samples than in the other animal parts investigated (P<0.05). The calcium contents of all the edible parts were higher in chicken than in the other animals. High calcium and phosphorus contents were detected in the faeces of chicken and goat, and that of cattle and goat, respectively. Low calcium and phosphorus contents were detected in the urine samples. Calcium: phosphorus ratios calculated for the bones of chicken, cattle and goat were satisfactory. Conclusions In conclusion, calcium and phosphorus contents of the animal parts vary significantly and their relative contents may be related to the animal's diet. Chicken parts may be the preferred dietary source of these minerals. This study highlights the need for routine investigation of the mineral contents of food, which is necessary for proper nutritional guidelines.

T1268 Gut Bio-Regulation in Health and Disease: Fermentonomic Insights – A Pilot Study

Background: Resident colonic bacteria, principally anaerobes and firmicutes, ferment undigested fibre, leading to the formation of volatile organic compounds (VOC). These are passed in faeces but also possibly absorbed and excreted in the urine. We hypothesised that the “fermentation profile” (FP), as seen in faeces and urine, may differ in health and in inflammatory bowel disease (IBD), and in the latter may change as the patient responds to treatment. Aim: Pilot study to determine if FP in faeces and urine can be recognised and reliably measured and to examine if there were identifiable differences in health and IBD. Methods: Healthy volunteers n=2; Longitudinal study of IBD patients: ulcerative colitis (UC) n=1, studied when acutely ill and when better on treatment; Crohn's disease (CD) n=1, at the beginning and during the course of Infliximab therapy. Samples of faeces and urine were analysed fresh and after storage for 2 weeks. VOC were released by heating (thermal desorption, TD) separated by gas chromatography (GC) and identified by mass spectroscopy (MS). The noise in GC data was cleaned using Clearview software ©Markes. Results: Initial technical developments were made using horse, cow and chicken faeces: each showed a very large number of peaks, some shared. Volunteers within-run variability: <15% for faeces but <10% for urine, reflecting its more uniform nature. Data from urine VOC is presented here. All individuals showed a wide range of peaks, which could be grouped into 5 broad categories (expressed as % of total compounds present). IBD patients showed higher levels of TAK but lower levels of TOA. The IBD VOC profile changed with improvement on treatment: CD: HB Index fell from 4 to 0 at week 6; the TOA and PG levels fluctuated. UC: SCA Index fell from 4 to 3; VOC profile showed changes similar to those in CD and in addition, loss of high molecular weight compounds. Conclusion: We have observed: 1 Clear differences in VOC profiles between healthy volunteers and IBD patients 2 Improvement in IBD during treatment was associated with change in VOC profile. We believe the study of FPs using TD-GC/MS offers new insights into gut health which have clinical relevance.

Safety of Beauveria bassiana (Bals.) Vuill. to Gallus domesticus L.

Beauveria bassiana, an important insect pathogen was used to evaluate its effect on the feeding, behavior, histology of the digestory system and anatomy of Gallus domesticus. The fungus (strain Unioeste 4) was administrated orally treated with chicken food. Chicken feces were collected, and the birds observed for 28 days. Also, were evaluated the weight of the birds, as well as any sign of intoxication or pathological modification. Tissue samples were withdrawn to test lesions with the optic microscope. There was 100% of survival of the birds, and no behavior alteration or external lesion was found. The test group presented the highest weight gain (1383.9±54.4g). Viable conidia were observed in the feces until 24 h after feeding the fungus, indicating that there was no germination inside the digestory system. No tissue lesion was observed, providing overwhelming evidence for the safety of B. bassiana to non-target organism G. domesticus.

P.174 DIAGNOSTIC ROLE OF CAPSULE ENDOSCOPY IN PATIENTS WITH SYMPTOMS HIGHLY COMPATIBLE WITH CROHN'S DISEASE

Background: Resident colonic bacteria, principally anaerobes and firmicutes, ferment undigested fibre, leading to the formation of volatile organic compounds (VOC). These are passed in faeces but also possibly absorbed and excreted in the urine. We hypothesised that the “fermentation profile” (FP), as seen in faeces and urine, may differ in health and in inflammatory bowel disease (IBD), and in the latter may change as the patient responds to treatment. Aim: Pilot study to determine if FP in faeces and urine can be recognised and reliably measured and to examine if there were identifiable differences in health and IBD. Methods: Healthy volunteers n=2; Longitudinal study of IBD patients: ulcerative colitis (UC) n=1, studied when acutely ill and when better on treatment; Crohn's disease (CD) n=1, at the beginning and during the course of Infliximab therapy. Samples of faeces and urine were analysed fresh and after storage for 2 weeks. VOC were released by heating (thermal desorption, TD) separated by gas chromatography (GC) and identified by mass spectroscopy (MS). The noise in GC data was cleaned using Clearview software ©Markes. Results: Initial technical developments were made using horse, cow and chicken faeces: each showed a very large number of peaks, some shared. Volunteers within-run variability: <15% for faeces but <10% for urine, reflecting its more uniform nature. Data from urine VOC is presented here. All individuals showed a wide range of peaks, which could be grouped into 5 broad categories (expressed as % of total compounds present). IBD patients showed higher levels of TAK but lower levels of TOA. The IBD VOC profile changed with improvement on treatment: CD: HB Index fell from 4 to 0 at week 6; the TOA and PG levels fluctuated. UC: SCA Index fell from 4 to 3; VOC profile showed changes similar to those in CD and in addition, loss of high molecular weight compounds. Conclusion: We have observed: 1 Clear differences in VOC profiles between healthy volunteers and IBD patients 2 Improvement in IBD during treatment was associated with change in VOC profile. We believe the study of FPs using TD-GC/MS offers new insights into gut health which have clinical relevance.

Serotype, genotype, and antimicrobial susceptibility profiles of Salmonella from chicken farms in Shanghai.

Five hundred fifty samples were collected from five chicken farms in Shanghai during March 2005 to October 2006. Twenty-five samples tested positive for Salmonella from a total of 550 samples, of which 500 were obtained from feces of healthy chickens and 50 were obtained from diseased chicks. The 25 presumptive Salmonella isolates were confirmed by the API 20E identification kit. Serotyping of these isolates by agglutination tests with antiserum displayed seven serovars; genotyping of these isolates with multilocus sequence typing demonstrated six sequence type (ST) patterns (i.e., ST-11, ST-19, ST-92, ST-96, ST-290, and ST-367). The multilocus sequence typing data revealed that some of these strains, isolated from different farms, might have the same ST and might come from the same source. The susceptibilities of these strains to 14 antimicrobials were determined; most of the isolates (13 of 25) were resistant to doxycycline and tetracycline, and two isolates were resistant to cefotaxime and ceftazidime, but none was resistant to gentamicin or kanamycin.

Semiochemical-Mediated Oviposition Avoidance by Female House Flies, Musca domestica, on Animal Feces Colonized with Harmful Fungi

House flies, Musca domestica, utilize ephemeral resources such as animal feces for oviposition and development of larval offspring, but they face competition with fungi that colonize the same resource. We predicted that house flies avoid oviposition on feces well-colonized with fungi, thereby reducing fungal competition for larval offspring. Working with fungal isolates from chicken feces, we have previously shown that prior establishment of Phoma spp., Fusarium spp., or Rhizopus spp. on feces significantly reduced oviposition by house flies. Here, we report that, in the headspace volatiles of these three fungal genera, five compounds (dimethyl trisulfide, an unknown, 2-phenylethanol, citronellal, norphytone) elicit responses from house fly antennae. In behavioral bioassays, dimethyl trisulfide and 2-phenylethanol significantly reduced oviposition by house flies. We conclude that fungus-derived volatiles serve as semiochemical cues that help house flies avoid resources colonized with fungal competitors for the development of larval offspring.

Probiotic Properties of Yeasts Isolated from Chicken Feces and Kefirs

The probiotic potential of 3 yeasts strains of Saccharomyces cerevisiae isolated from kefirs and feces was investigated and compared with 3 isolates from medicines and 2 collection strains (ATCC) of Saccharomyces cerevisiae var. boulardii. Genetic identification of yeasts based on karyotypes indicated their affiliation to Saccharomyces spp. although chromosomal polymorphism was observed. Concerning probiotic characteristics survival in simulated gastric and intestinal environment were examined. The survival of all tested yeasts in medium of pH 2.5 was comparable and equaled 86.8-97.1% after 8 hours of incubation at 37 degrees C. The fecal isolate, probiotic and collection yeasts showed also high resistance to pH 1.5 and their survival was 85.3-92.1%, whereas for kefir strains it amounted to 33.1 and 38.9%. All yeasts tested demonstrated high resistance to synthetic bile salts as well. In the presence of 0.1% sodium cholate and sodium deoxycholate the reduction of cell number by only 1 log unit after 4 hours of incubation at 37 degrees C was observed. However, 1.0% addition of ox bile did not affect their viability. In simulated gastric and intestinal environment survival of fecal, probiotic and collection strains was 86.3-93.7% after 4 hours of incubation in media with addition of 3 g/l pepsin and 1 g/l pancreatin. Kefir isolates were more sensitive to these conditions and a further 10% reduction of cell number in relation to probiotic yeasts was observed. The tested strains, except for kefir isolates, were able to grow at 37 degrees C. All the tested strains survived in sufficient number to create the possibility of proper action in the human body, although fecal, probiotic and collection strains tolerated the conditions of the human gastrointestinal tract better than food-borne yeasts.

Partial Purification and Characterization of the Mode of Action of Enterocin S37: A Bacteriocin Produced byEnterococcus faecalisS37 Isolated from Poultry Feces

The aim of this research was to purify and characterize the mode of action of enterocin S37, a bacteriocin produced by Enterococcus faecalis S37, a strain recently isolated from the chicken feces. Enterocin S37 has a molecular weight comprised between 4 and 5 kDa. It remained active after 1 h at 80oC and at pH values ranging from 4.0 to 9.0. Furthermore, cell-free supernatant of Enterococcus faecalis S37 and purified enterocin S37 were active against Gram-positive bacteria including Listeria monocytogenes EGDe, L. innocua F, Enterococcus faecalis JH2-2, and Lactobacillus brevis F145. The purification of enterocin S37 was performed by ammonium sulfate precipitation followed up by hydrophobic-interaction chromatography procedures. Treatment of enterocin S37 with proteinase K, α-chymotrypsin, and papain confirmed its proteinaceous nature, while its treatment with lysozyme and lipase resulted in no alteration of activity. Enterocin S37 is hydrophobic, anti-Listeria and likely acting by depletion of intracellular K+ ions upon action on KATP channels. This study contributed to gain more insights into the mode of action of enterocins.