Staphylococcus aureus is the leading cause of intoxications in humans. Also, methicillin-resistant S. aureus (MRSA) is an emerging problem in food-producing animals. The presence of MRSA in milk may create a risk to public health. The aim of this study was to evaluate the presence of MRSA in bulk tank milk samples. Dne hundred and twenty bulk tank milk samples were analyzed using the convenient sampling method. The isolates were confirmed by real-time polymerase chain reaction (RT-PCR) targeting nuc and mecA gene in S. aureus. Antibiotic resistance profiles of the isolates were tested by disc agar diffusion method. On the current study, S. aureus was detected in 44 (36.66%) of the samples. The presence of the mecA gene was found to be positive in 40 (75.4%) of the 53 S. aureus isolates. As a result of the study, a high incidence of MRSA was detected in bulk tank milk samples. Antibiotic-resistant bacteria are at risk of being transferred to humans via milk. For safe and healthy milk consumption, uncontrolled use of antibiotics in dairy cows should be avoided.

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Salmonella Enteritidis is the major cause of foodborne salmonellosis affecting human health. The light emitting diodes (LEDs) is a novel approach to inactivate of the foodborne pathogens. The aim of this study was to determine the antibacterial effect of 405 nm LEDs illumination on S. Enteritidis and S. Enteritidis PT4. The irradiance of the 405 nm LEDs was 27.7 mW/cm 2 . Bacterial cultures suspended in tryptic soy broth were illuminated by 10-watt LEDs at a distance of 4.5 cm for 24 hours at 4 °C, 25 °C and 37 °C. Approximately 7-log reduction in colony forming unit (CFU) counts of both S. Enteritidis and S. Enteritidis PT4 at each temperature were observed following exposure after 7.5 hours to the LEDs, concluding that temperature did not affect the inactivation of the bacteria. The decimal reduction times (D-values) for the serotypes ranged from 55.78 to 67.88 min at 4, 25 and 37 °C after 405 nm LEDs illumination. No significant difference in D-values was observed among both the serotypes and temperatures, except for S. Enteritidis which had lower D-value at 4 °C. The LEDs technology has shown antibacterial efficacy and can be implemented in the food processing for reducing S. Enteritidis.

Salmonella Enteritidis is amongst the most common causes of foodborne salmonellosis. Multi-drug resistant Salmonella strains has been associated with treatment failures. Plant-derived phytochemicals may be an alternative to antibiotics in combating these bacteria. The purpose of this study is to investigate the antibacterial activity of curcumin, carvacrol and styrax liquidus on S. Enteritidis and S. Enteritidis PT4.Minimum inhibitory concentration (MIC) values of these substances were detected at 1.5, 3, 7.5 and 24 h by broth microdilution method to evaluate their time-dependent antibacterial activities. The findings of the present study showed that MIC values of carvacrol, curcumin and styrax liquids for both S. Enteritidis and S. Enteritidis PT4 were 125.0 µg/mL, 132.5 µg/mL, 31.3 mg/mL for 24 h, respectively. Also, a time-dependent change was observed in the MIC values of curcumin. Carvacrol, curcumin and styrax liquidus can be used to provide antimicrobial effect on S. Enteritidis and S. Enteritidis PT4 in food applications, taking into account the MIC values and contact times.

Ochratoxin A (OTA) produced by several Aspergillus and Penicillium species is a mycotoxin that contaminates different foods and feedstuffs, including cereals, coffee beans, nuts, cocoa, pulses, beer, wine, spices, dried vine fruits, meat, milk. In humans and animals, OTA has been observed to be particularly nephrotoxic, hepatotoxic, immunotoxic, neurotoxic, embryotoxic, carcinogenic and teratogenic. Ochratoxin A is a stable molecule and can remain unchanged even after the processes applied. In this study, it was aimed to determine the presence of ochratoxin A in milk samples (n:40) collected from bulk tank milks in Burdur province of Turkey. The presence of OTA in the samples was analyzed by using ELISA. The analyzes were performed according to the manufacturer's instructions. As a result, Ochratoxin A was found in 40 cow's milk samples (range 2-270 ng/l) collected from bulk milk tanks. The results of this study show that cow's milk should be considered as a potential OTA source in the human diet. It is proposed to examine the presence of OTA more intensively in dairy products and to determine their maximum limit values by conducting necessary studies. Süt Toplama Tanklarında Okratoksin A Varlığının Belirlenmesi ÖZOkratoksin A (OTA), Aspergillus ve Penicillium türü mantarlar tarafından sentezlenen ve tahıl, kahve çekirdeği, fındık, kakao, bakliyat, bira, şarap, baharat ve kuru üzümde bulunabilen bir mikotoksindir. İnsanlarda ve hayvanlarda, OTA özellikle nefrotoksik, hepatotoksik, nörotoksik, embriyotoksik, immunotoksik, teratojenik ve karsinojenik etkiler gösterir. Okratoksin A kısmen kararlı bir moleküldür ve gıdalara uygulanan işlemlerden sonra bile değişmeden kalabilir. Bu çalışmada; Burdur bölgesinde bulunan süt toplama tanklarında (n:40) OTA varlığının belirlenmesi amaçlandı. Örneklerde OTA varlığı ELISA kullanılarak analiz edildi. Analizler üreticinin talimatlarına göre yapıldı. Süt toplama tanklarından alınan 40 inek süt örneğinde (2-270 ng/l aralığında) OTA bulundu. Bu çalışmanın sonuçları, inek sütünün insan beslenmesinde potansiyel bir OTA kaynağı olarak görülmesi gerektiğini göstermektedir. OTA varlığını süt ürünlerinde daha yoğun bir şekilde incelenmesi ve gerekli mevzuat çalışmaları yapılarak maksimum limit değerlerinin belirlenmesi önerilmektedir.

Summary:Ionophore antibiotics in sub-therapeutic doses have been used since 1970s to improve ruminal fermentation. But use of antibiotics as feed additives was banned in the European Union and Turkey in 2006 since they leave residues in animal products and develop resistance in bacteria. This has shifted the focus of the studies to safer alternatives such as plant extracts and their secondary metabolites to alter ruminal fermentation in order to improve ruminant productivity. In this review, general and recent knowledge about plant extracts and plant secondary metabolites as modifiers of ruminal fermentation are summarized. Furthermore, potential efficacies and possible disadvantages of these substances are also discussed.Keywords: Plant extracts, plant secondary metabolites, rumen fermentation.

How to Cite This ArticleDemirtas A, Musa SAA, Pekcan M, Salgirli Demirbas Y, Piskin I, Emre B, Toprak N, Ozturk H: Effects of cleavers (Galium aparine) and yarrow (Achillea millefolium) extracts on rumen microbial fermentation in in-vitro semi-continuous culture system (RUSITEC). Kafkas Univ Vet Fak Derg, 26 (3): 385-390, 2020. AbstractExperimental data on the effects of cleavers (Galium aparine) and yarrow (Achillea millefolium) extracts on rumen microbial fermentation are scarce. The objective of this study was to determine the effects of cleavers and yarrow extracts on in vitro ruminal fermentation. Incubation trial was carried out using the long-term rumen simulation technique (RUSITEC). The experiment lasted 10 days. After an adaptation period of 5 days, the fermentation vessels divided into 3 groups; first three vessels received no additives (control), second three vessels received 500 mg/L cleavers extract daily, and third three vessels received 500 mg/L yarrow extract daily. Supplementations of cleavers and yarrow extracts had no significant effect on ruminal pH, total volatile fatty acids (VFA), acetate, propionate and methane production, NH3-N concentration and, total protozoa. However, both extracts decreased dry matter digestibility (DMD) (P<0.05). Butyrate production, on the other hand, increased with cleavers extract (P<0.05). In conclusion, there were only small effects of cleavers and yarrow extracts on the investigated microbial fermentation characteristics. Nevertheless, it may be considered advantageous for feed conversion that plant extracts did not suppress ruminal fermentation in spite of decreasing DMD. Yoğurt Otu (Galium aparine) ve Civan Perçemi (Achillea millefolium) Ekstraktlarının In-vitro Yarı-Sürekli Kültür Sisteminde (RUSITEC) Rumen Mikrobiyal Fermentasyonu Üzerine EtkileriÖz Yoğurt otu (Galium aparine) ve civan perçemi (Achillea millefolium) ekstraktlarının rumen mikrobiyal fermentasyonu üzerine etkileri ile ilgili sınırlı düzeyde deneysel veri bulunmaktadır. Bu çalışmanın amacı, yoğurt otu ve civan perçemi ekstraktlarının in vitro ruminal fermentasyon üzerine etkilerinin araştırılmasıdır. Inkübasyon denemesi uzun-süreli rumen simülasyon tekniği (RUSITEC) kullanılarak gerçekleştirilmiştir. Deneme 10 gün sürmüştür. Beş günlük bir adaptasyon periyodunu takiben fermenterler 3 gruba bölünmüştür; ilk üç fermentere ilave yapılmamış (kontrol), ikinci üç fermenterlik gruba günlük 500 mg/L yoğurt otu ekstraktı, üçüncü üç fermenterlik gruba ise günlük 500 mg/L civan perçemi ekstraktı eklenmiştir. Yoğurt otu ve civan perçemi ilaveleri, ruminal pH, toplam uçucu yağ asitleri (UYA), asetat, propiyonat ve metan üretimi, NH3-N konsantrasyonu ve toplam protozoa üzerine önemli bir etki oluşturmamıştır. Ancak her iki ekstrakt da kuru madde sindirilebilirliğini (KMS) azaltmıştır (P<0.05). Diğer taraftan, bütirat üretimi, yoğurt otu ekstraktı ilavesi ile artış göstermiştir (P<0.05). Sonuç olarak, incelenen mikrobiyal fermentasyon özellikleri üzerine yoğurt otu ve civan perçemi ekstraktları sadece küçük...

Nisin is a low molecular weight bacteriocin which is produced by Lactococcus lactis. Literature about the effects of nisin on pure cultures of rumen bacteria is scarce. The objective of the present study was to investigate the comparative effects of nisin and monensin on pure cultures of some Gram-positive and Gram-negative rumen bacteria. The antibacterial activity assays of nisin and monensin were carried out using broth microdilution method in anaerobic conditions. Antibacterial effect of monensin on Gram-positive rumen bacteria was higher than nisin. Ruminococcus albus and Eubacterium ruminantium were the most sensitive bacteria to monensin. Growth of these bacteria was inhibited completely by monensin, at 6 and 12 µg/mL concentrations respectively. Nisin exhibited stimulatory effects on R. albus, E. ruminantium and, Streptecoccus bovis (p<0.05), unlike monensin. Both nisin and monensin showed potential antibacterial activity on Ruminococcus flavefaciens and Butyrivibrio fibrisolvens (p<0.05), although they did not inhibit these bacteria completely. Nisin and monensin also did not show inhibitory effect on Methanobacterium formicicum, however the potential antimicrobial activity of monensin on this methanogen was more evident. Gramnegative rumen bacteria, Megasphaera elsdenii and Fibrobacter succinogenes, were resistant to both of nisin and monesin. It was concluded that the different effects of nisin and monensin particularly on some Gram-positive rumen bacteria may be responsible for their inconsistent effects on ruminal fermentation. How to cite this article: Demirtaş A: Comparative effects of nisin and monensin on pure cultures of rumen bacteria.