Ivana S. Čabarkapa

Screening of mycotoxins in animal feed from the region of Vojvodina

This paper shows the results of screening of mycotoxins in animal feed originating from the region of Vojvodina. Permanent screening is needed on all levels of production and storage, as well as the use of known methods to reduce mould contamination or toxin content in feedstuffs and feed. A total of 56 representative samples were collected from feed companies from the region of Vojvodina. Samples were collected during February 2009. The collected samples included 41 samples of feedstuffs (soybean, soybean meal, soybean grits, soybean cake, maize, sunflower meal, barley, wheat feed flour, rapeseed meal, dehydrated sugar beet pulps, alfalfa meal, yeast, dried whey, fish meal, meat-bone meal) and 15 samples of complete feedingstuffs. The amounts of aflatoxins, ochratoxin A, zearalenone, fumonisin and deoxynivalenol were determined. Screening method for the analysis was done using Neogen Veratox® testing kits. The test itself is a competitive direct enzyme-linked immunosorbent assay (CD-ELISA). Mycotoxins were present in 71.4% of the samples, but the values determined were below the maximum allowed limits for both Serbian and EC reference values. Zearalenone was found with the highest incidence (57.1% of samples), followed by ochratoxin A (37.5%), fumonisin (33.9%), deoxynivalenol (14.3%) and aflatoxins (3.6%).

Influence of growth conditions on biofilm formation of Listeria monocytogenes

Listeria monocytogenes is ubiquitous in nature and a major concern for the food industry, since it is the causal agent of the serious foodborne illness listeriosis. This organism can be introduced through many routes to food-processing environments and may become established on food-processing equipment. Subsequently, food products may become contaminated during processing. In addition, the bacterium can grow at refrigeration temperatures. Biofilms are regarded as important with respect to the survival and growth of microorganisms in the food industry. Microorganisms growing in biofilms are protected against cleaning and disinfection and are difficult to eradicate. L. monocytogenes may grow in biofilms that protect them against environmental stress and can be isolated from surfaces after cleaning and disinfection. In this study, a total of eight L. monocytogenes strains isolated from the meat industry and one reference strain L. monocytogenes ATCC 19111 were studied for their capability to form a biofilm. The biofilm forming behavior of nine L. monocytogenes strains was determined in two different media, Tryptone soya yeast extract broth (TSYEB) or Brain-heart infusion broth (BHI), at temperatures 7 °C, 25 °C, 37 °C, 42 °C for 5 days. The method used to assess biofilm formation was crystal violet staining. All strains were able to form biofilm, but the growth condition affected the levels formed. The lowest biofilm formation was observed at 7 °C. Further, the most effective medium in promoting biofilm production by the L. monocytogenes isolates from meat was BHI medium while for reference strain L. monocytogenes ATCC 19111 it was TSYEB. Incubation temperature was the most significant factor influencing the biofilm production levels, and also the type of used nutritive medium was important factor.

RDAR morphotype: A resting stage of some Enteroba cteriaceae

Bacteria of the genus Salmonella, some Escherichia coli strains as well as other species of the family Enterobacteriaceae, manifest the ability to express a specific phenotype, which is commonly termed as the „rdar” (red, dry and rough) morphotype. Both rdar and non-rdar phenotypes are commonly found in the nature; however, rdar is of essential importance for bacterial survival in the environment, outside of the host organisms. In that respect, it is comparable with the process of spore formation in Gram-positive bacteria. In laboratory conditions, rdar morphotype demonstrates growth of aforementioned organisms on agar containing diazo dye Congo Red, appearing as dark red (violet), rough and irregularly margined colonies. A coordinated expression of the number of genes mediated by major transcriptional regulators CsgD (curli subunit gene D) is the prerequisite for the formation of rdar morphotype colonies. The key point in this process is the activation of csgBAC operon transcription, which encodes the synthesis of curli fimbriae and activates the AgfD regulated gene (AdrA) involved in the cellulose biosynthesis. Curli fimbriae and cellulose are two basic structural components of the rdar morphotype. Curli fimbriae enable initial surface adhesion and intercellular aggregation of bacteria, whilst the cellulose (and other exopolysaccharides) promotes intercellular interactions. CsgD affects the overall cell physiology towards a „bacterial multicellular behavior“ pattern, such as biofilm formation. The colony growth on Congo Red agar is a widely accepted laboratory method used for bacteria from the family Enterobacteriaceae and highly conserved between Salmonella. However, repeated laboratory subpassaging results in the substantial loss of rdar morphotype and the formation of smooth mutants, suggests the necessity for using wild isolates. In this article, the characteristics of rdar and non-rdar morphotypes of diverse Salmonella serotypes isolated from animal feed, as well as Escherichia coli isolates originating from cows milk with clinical mastitis, were presented. The research indicates substantial importance of the rdar phenotype for the persistence of Salmonella in the environment and its entering the food chain as well as the potential role of rdar phenotype of Escherichia coli in the pathogenesis of recurrent coli mastitis in dairy cows.

Beneficial properties of probiotic yeast Saccharomyces boulardii

Saccharomyces boulardii is unique probiotic and biotherapeutic yeast, known to survive in gastric acidity and it is not adversely affected or inhibited by antibiotics or does not alter or adversely affect the normal microbiota. S. boulardii has been utilized worldwide as a probiotic supplement to support gastrointestinal health. The multiple mechanisms of action of S. boulardii and its properties may explain its efficacy and beneficial effects in acute and chronic gastrointestinal diseases that have been confirmed by clinical trials. Caution should be taken in patients with risk factors for adverse events. Its potential application in various dairy foods could offer an alternative probiotic product to people suffering from antibiotic‐associated diarrhea. This review discusses the evidence for efficacy and safety of S. boulardii as a probiotic for the prevention and therapy of gastrointestinal disorders in

Impact of antibiotics used as growth promoters on bacterial resistance

For decades intensive husbandry has more or less been based on the use of antibiotics in sub-minimum inhibitory concentrations (sub-MIC) aimed at growth promotion. Continuous exposure of animal intestinal microbiota, including opportunistic zoonotic pathogens, to sub-MIC poses a pressure to selection and spread of bacteria strains with developed mechanism of antibiotic resistance. These bacteria may be transferred to people either by direct contact with farm animals or indirectly, via the food chain. Although in the EU a ban on the use of antibiotics as growth promoters was imposed in 2006, in many countries, including the largest producers and consumers of antibiotics in the world, it has yet to be done. Given that we are faced with a global problem of the loss of the efficacy of several antibiotic classes which are available for the treatment of human bacterial infections, it is unacceptable that antibiotic use in husbandry is not under global control. Reduction in antibiotic use in clinical practice in human medicine remains in dispute, but non-therapeutic use in husbandry remains a field in which much can be done to contribute substantially to the extension of antibiotic effectiveness and health care of future generations.

Effect of Origanum heracleoticum L. essential oil on food-borne Penicillium aurantiogriseum and Penicilium chrysogenum isolates

Molds are ubiquitously distributed in nature and their spores can be found in the atmosphere even at high altitudes. The difficulty of controlling these undesirable molds, as well as the growing interest of the consumers in natural products, have been forcing the industry to find new alternatives for food preservation. The modern trends in nutrition suggest the limitation of synthetic food additives or substitution with natural ones. Aromatic herbs are probably the most important source of natural antimicrobial agents. Origanum heracleoticum L. essential oil has been known as an interesting source of antimicrobial compounds to be applied in food preservation. In the this work, we have investigated the effect of essential oil obtained from O. heracleoticum on growth of six isolates of Penicillium aurantiogriseum and four isolates of Penicillium chrysogenum isolated from meat plant for traditional Petrovacka sausage (Petrovska klobasa) production. The findings reveal that the essential oil of O. heracleoticum provides inhibition of all of fungal isolates tested. O. heracleoticum L. essential oil exhibited higher antifungal activity against the isolates of P. chrysogenum than the isolates of P. aurantiogriseum. O. heracleoticum essential oil showed a MIC value ranging from 25 to 100 μL/mL. The fungi cultivated in the medium with higher concentration of essential oil showed certain morphological changes. The alterations included lack of sporulation and loss of pigmentation.

Effect of Artemisia absinthium essential oil on antioxidative systems of broiler's liver

The effect of Artemisia absinthium essential oil (AAEO) on enzymatic activity of super-oxide-dismutase (SOD), glutathione-peroxidase (GSHPx), glutathione-reductase (GR), peroxidase (POD), xantine-oxidase (XOD) and non-enzymatic (content of lipid peroxides (LPx) and gluthathione (GSH)) antioxidative status of broilers infected with mixture of oocysts of Eimeria tenella, Eimeria mitis and Eimeria necatrix in comparison to coccidiostat salinomycin was investigated. The in vivo investigation were carried out on 120 Arbor acres broilers of both sexes. Broilers were randomly distributed into four groups. Group A was uninfected and untreated; group B was infected and was kept untreated; group C preventively received coccidiostatic salinomycin in quantity of 60 mg/kg of feed and was inoculated with coccidia species at 21st day-of-age and group D received in feed AAEO in quantity of 3 g/kg and was infected with Eimeria oocysts at 21st day-of-age. Livers were collected for the subsequent evaluation of antioxidative status. It was concluded that AAEO added in feed for broilers prevented the development of coccidia oocysts and therefore it can be used as prophylactic feed additive.

Effect of synbiotic on growth and antioxidant status of blood in broiler chicken

In the present study, the impact of synbiotic, compared to control treatment (CON), on growth performance and antioxidative status of broilers blood was investigated. The experiment was carried out on a total of 500 one-day-old broiler chickens of both sexes. The broilers were divided into two treatments with five replicates, based on a completely randomized design. The control treatment was fed basal diet, while experimental treatment was supplemented with synbiotic in addition of 1 g/kg of feed (SYN) in finisher period that lasted from 15 to 42 days of age. Diet supplementations with synbiotic led to increased body weight of broilers, compared to the control treatment. During the last 28 days, feed conversion ratio was significantly (P<0.05) improved in the synbiotic treatment (2.12), compared to the control treatment (2.21). The serum glutathione peroxidase, peroxidase, glutathione reductase and catalase activities were significantly higher (P<0.05), except of superoxide dismutase, in the supplemented treatment compared to the control treatment. Furthemore, there were noticed significant decreases (P<0.05) in malondialdehyde and glutathione content in the supplementary treatment. Based on the previously mentioned, it can be concluded that synbiotic can be applied as a growth promoter and as a natural antioxidant feed additive in broilers diet.

Epidemiological significance of Salmonella enterica serovar Montevideo and the potential role of feed for their entry into the food chain

Animal feed is the first link in the food chain and one of the possible source of Salmonella for food producing animals and consequently, humans consuming products of animal origin. The assessment of the importance and role of Salmonella organisms commonly detected in animal feed in epidemic outbreaks of salmonellosis is highly intricate. This is mainly due to the fact that isolates are rarely identified (typed) to the serovar level, thus, the relevant data on both animal feed and food of animal origin are lacking. In the framework of the 2-year project granted by the Ministry of Science and Technological Development of the Republic of Serbia, all Salmonella isolates originating from animal feed were typed to the serovar level in the National Reference Laboratory for Salmonella. Eighteen different serovars have been identified, whereas 15% of all isolates included serovar Montevideo. Frequent isolation of S. ser. Montevideo from animal feed originating from feed mills in our epizootic area (South Backa and Srem district), encouraged our attempt to summarize and present the available data on the importance of Montevideo serovar in the outbreaks of clinical salmonellosis in humans and to review the reports on individual epidemiological studies aimed at detecting infection sources and establishing relevant facts on emerging antimicrobial resistance of Salmonella. Moreover, this article emphasizes the need and importance of an extensive Salmonella monitoring program at national level, which would encompass all links of the food chain including animal feed and feed processing plants as well.