Inaktivacija bakterije Listeria monocytogenes u podlozi s agarom i goveđim mesom pomoću UVC zraka

The aim of this study is to evaluate the eff ect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To bett er understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but diff erent chemical composition might produce very diff erent inactivation results when exposed to UVC light.Svrha je ovoga rada bila ispitati učinak sastava (udjela mesa) i teksture podloge s agarom i goveđim mesom na inaktivaciju bakterije Listeria monocytogenes pomoću kratkovalnog ultraljubičastog (UVC) zračenja. Podloge su pripremljene s različitim udjelima komadića mesa te s otopinom agara. Podloge s goveđim mesom, selektivne podloge za izolaciju bakterije Listeria monocytogenes (engl. Listeria selective agar, LSA) i kuhani goveđi odresci inokulirani su bakterijom L. monocytogenes i zatim izloženi UVC zračenju. Populacija se L. monocytogenes na LSA podlozi nakon zračenja smanjila ispod granice detekcije. U podlogama s većim udjelom mesa preživio je i veći broj bakterija. Najviše je bakterija preživjelo na kuhanom goveđem odresku. Za bolje shvaćanje utjecaja površinskih nepravilnosti na inaktivaciju bakterija interferometrom su analizirane podloge s goveđim mesom i LSA podloga. U sedam od devet uzoraka nije utvrđena nikakva korelacija između površinskih neravnina i stupnja inaktivacije bakterije UVC zračenjem. U podlogama s većim udjelom mesa inaktivirano je manje stanica bakterija. Rezultati ovog istraživanja pokazuju da kemijski sastav uzorka ima bitnu ulogu u rezistenciji i preživljavanju patogena, što znači da na površinama sličnih tekstura ali različitog kemijskog sastava inaktivacija UVC zračenjem može imati sasvim različit učinak

The Effect of Planting Date and Seed Moisture Content at Harvest on Seed Germination Indices of Corn (Zea mays) Cv. S.c704-Produced in Ardebil Province (Moghan)

This experiment was conducted as a factorial experiment based on a completely randomized design with three replications at two locations: Agricultural and natural resource center of Ardebil province (Moghan) and seed and plant certification and registration institute of Karaj in 2013. The treatments included: planting date in three levels (10-May, 25-May and 9-Jun), seed moisture content at harvest time in four levels (30%, 25, 20 and 15) and seed size in three levels (flat, round and medium). The measured traits were a standard germination test, mean time of germination, seedling weight and length vigor index, germination percent in radical emergence test and germination percent in cold test. The results illustrated that delayed planting caused reduction of seed quality and this reduction was more obvious in delayed harvest (15%), also the reduction rate in round seeds was more than flattered and medium seeds. The minimum percentage of germination and vigor were seen in round seeds of third planting date and moisture harvest by 15%. So it is recommended for corn seed production to sow the seeds before the last week of May and when seed moisture content reached 30 percent, cob harvesting should be started and the harvest not is delayed

Physiological traits and relative abundance of species as explanatory variables of co-occurrence pattern of cultivable bacteria associated with chia seeds

Deciphering the rules defining microbial community assemblage is envisioned as a promising strategy to improve predictions of pathogens colonization and proliferation in food. Despite the increasing number of studies reporting microbial co-occurrence patterns, only a few attempts were made to challenge them in experimental or theoretical frameworks. Here, we tested the hypothesis that observed variations in co-occurrence patterns can be explained by taxonomy, relative abundance and physiological traits of microbial species. PCR amplicon sequencing of taxonomic markers was first conducted to assess distribution and co-occurrence patterns of bacterial and fungal species found in 25 chia (Salvia hispanica L.) samples originating from eight different sources. The use of nutrient-rich and oligotrophic media enabled isolation of 71 strains encompassing 16 bacterial species, of which five corresponded to phylotypes represented in the molecular survey. Tolerance to different growth inhibitors and antibiotics was tested to assess physiological traits of these isolates. Divergence of physiological traits and relative abundance of each pair of species explained 69% of the co-occurrence profile displayed by cultivable bacterial phylotypes in chia. Validation of this ecological network conceptualization approach to more food products is required to integrate microbial species co-occurrence patterns in predictive microbiology.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Molecular Detection and Genotyping of Toxoplasma gondii in Chicken, Beef, and Lamb Meat Consumed in Northwestern Iran

Background: Toxoplasma gondii, the obligate, intracellular parasite afflicts human in diverse ways such as ingestion of tissue cysts in undercooked meat. The aim of this study was to assess the prevalence and genotyping of Toxoplasma isolated from meat samples being consumed in East Azerbaijan, Northwest of Iran. Methods: Overall, 150 samples including chicken, beef and lamb meat were collected from retailers in different regions of Tabriz, northwestern Iran during April to September 2014. Molecular detection was done by amplifying B1 gene and T. gondii surface antigen 2 (SAG2) loci. For genotyping of T. gondii, restriction fragment length polymorphism (RFLP) was performed using Sau3AI and HhaI restriction enzymes. Finally, three positive isolate from each host was sequenced to evaluate and phylogenetic analysis. Results: Overall, 26 (17.33%) samples were positive for T. gondii including 4 (8%) isolate from chicken, 8 (16%) isolates from cattle and 14 (28%) isolates from sheep. According to the RFLP patterns, sequencing and phylogenetic results, all of the samples were identified as genotype I. Conclusion: The results indicated a potential risk of transmission of the disease through the consumption of infected meat. This is particularly important especially for pregnant women and immuno-compromised patients and this suggests that the training on the prevention of infection is necessary

Hydatid Cyst Surgeries in Patients Referred to Hospitals in East Azerbaijan Province during 2009-2011

Background: Hydatidosis, as the most important zoonotic parasitic disease in Iran, has posed many health and economic losses. This study was conducted to investigate the demographic characteristics of hydatid cyst surgeries in hospitals of East Azerbaijan Province, Northwest of Iran. Methods: Demographic characteristics of all patients with hydatid cyst surgery in hospitals of the province, during 2009-2011 were gathered including age, gen-der, occupation, number and location of the cyst, clinical symptoms, place of residence and history of contact with dog. They were extracted from reports of health center and were analyzed using STATA 11 software. Results: Out of 52 hydatid cyst surgeries, 27 cases were females. Mean age of patients was 38.3 yr. Liver was reported as the most involved organ. The most clinical symptoms were abdominal and liver pain. Housewives comprised the most victims of the disease. Forty seven percent of patients had one cyst and 59% had the history of contact with dog. The majority of the patients were liv-ing in rural areas. Conclusion: Due to the high costs of diagnosis and treatment of hydatidosis, collecting data on the prevalence and transmission of the disease as well as on vulnerable groups seems to be essential as the first step in controlling and pre-venting the disease