The sugarcane aphid, Melanaphis sacchari Zehntner (Hemiptera: Aphididae), is the main pest of sorghum, Sorghum bicolor L. Moench (Poaceae), in Mexico. To control this insect, farmers currently use synthetic chemical insecticides, which are toxic to humans and biodiversity. However, natural products are a promising potential source of safer alternative means to control different agricultural pests. The main objective of this study was to evaluate the insecticidal effect of contact by fumigation of pure molecules of four commercial fatty acids (palmitic, stearic, pentadecanoic and linoleic acids), the phytosterol ß -sitosterol, and the flavonoid rutin. The results showed that fatty acids were the most effective against M. sacchari ; the highest mortality rate (85%) was produced by linoleic acid and the LC 50 was 1,181 ppm, followed by stearic and palmitic acids with mortality percentages of 74 and 63%, respectively, at a concentration of 2,500 ppm at 72 h. The positive control, imidacloprid, had 100% mortality in 24 h and the tween 20 negative control exhibited 4% mortality in 72 h. Our results show that commercial fatty acids are effective against adults of M. sacchari , and can be considered an environmentally friendly alternative to the frequent use of synthetic chemical insecticides.
This study investigated the ultraviolet (UV) light-induced effect of chitosan-titanium dioxide-silver (CTS-TiO2-Ag) nanocomposite film solution against Penicillium steckii ( ( P. steckii ) , as well as the underlying the physiological mechanism. The results indicated that the longer the UV exposure time, the better the pathogenic inhibition effect. After UV photoinduced treatment for 120 min, the colony diameter of P. steckii was the smallest at 4.85 mm. However, when this process is followed by an 8-h storage period, the conductivity of the P. steckii culture medium reached its highest level at 713 μs/cm. After a 120 h growth period in the same conditions, the lesion diameters and pathogenicity of the mangoes reached 12.61 mm and 41.67%, respectively. Since the cell membrane was severely disrupted, its permeability increased, causing serious intracellular protein and nucleic acid material extravasation. Furthermore, the malondialdehyde (MDA) , catalase (CAT) and superoxide dismutase (SOD) in the P. steckii reached maximum levels after 8 h of incubation, at 2.1106 μmol/mL, 44.06 U/mL, and 24.67 U/mL respectively. These results indicated significant P. steckii inhibition via the UV light induction of the CTS-TiO 2 -Ag composite film solution.
Nowadays, the global fish consumption continues to rise along with the continuous growth of the population, which has led to the dilemma of overfishing of fishery resources. Especially high-value fish that are overfished are often replaced by other fish. Therefore, the accurate identification of fish products in the market is a problem worthy of attention. In this study, full-DNA barcoding (FDB) and mini-DNA barcoding (MDB) used to detect the fraud of fish products in Guiyang, Guizhou province in China. The molecular identification results showed that 39 of the 191 samples were not consistent with the labels. The mislabelling of fish products for fresh, frozen, cooked and canned were 11.70%, 20.00%, 34.09% and 50.00%, respectively. The average kimura 2 parameter distances of MDB within species and genera were 0.27% and 5.41%, respectively; while average distances of FDB were 0.17% within species and 6.17% within genera. In this study, commercial fraud is noticeable, most of the high-priced fish were replaced of low-priced fish with a similar feature. Our study indicated that DNA barcoding is a valid tool for the identification of fish products and that it allows an idea of conservation and monitoring efforts, while confirming the MDB as a reliable tool for fish products.
The goals of this study were to evaluate the persistence and the virulence potential of Listeria monocytogenes isolated from beef carcasses obtained in processing facilities in the Southern region of Rio Grande do Sul, Brazil, based on pulsed field gel electrophoresis (PFGE), invasion ability in human colorectal carcinoma cells (HCT-116), InlA expression by western blot (WB) and identification of mutation points in the inlA . PFGE profiles demonstrated that L. monocytogenes isolates were grouped based on their previously identified lineages and serogroups (lineage I: serogroups IIb, n = 2, and IVb, n = 5; lineage II, serogroup IIc, n = 5), isolates with indistinguishable genetic profiles by this method were obtained from different slaughterhouses and sampling steps, with up to 3-year interval. Seven isolates showed high invasion ability (2.4 to 7.4%, lineage I, n = 6, lineage II, n = 1) in HCT and expressed InlA. Five isolates showed low cell invasion ability (0.6 to 1.4%, lineage I, n = 1, lineage II, n = 4) and did not express InlA, and two of them (lineage II, serogroup IIc) presented mutations in inlA leading to a premature stop codon (PMSC) type 19, at position 326 (GAA → TAA). The results demonstrated that most of L. monocytogenes isolates from Lineage I expressed InlA and were the most invasive in HCT indicating their high virulence potential, while most isolates from Lineage II showed attenuated invasion due to non-expression of InlA and the presence of PMSC type 19 in inlA . The obtained results demonstrated that L. monocytogenes with indistinguishable PFGE profiles can be persisting or being reintroduced in beef processing facilities in the studied region and differences on their virulence potential based on their lineages and serogroups.
In this study, we evaluated the microbial contamination status of cold dishes consumed by residents of Jilin Province and investigated to determine the incidence of four pathogenic bacteria in cold dishes. A total of 300 samples of cold dishes including meat, vegetable and mixed products, were collected from three different purchasing places: supermarkets, farmers' markets and mobile vendors. Live bacteria were isolated using conventional culture methods. After separation, a quick and easy polymerase chain reaction (PCR) was used to detect Listeria monocytogenes , Staphylococcus aureus , Enterotoxic Escherichia coli and Salmonella . The results showed that the total number of microbial colonies in the vegetable samples exceeded the standard rate of 8%, and the total number of microbial colonies in the meat and mixed samples did not exceed the standard. The total microbial colony count exceeded the standard in all three different procurement sites, with the highest exceedance of 7.4% in the mobile vendor sites. The detection rates of Enterotoxigenic Escherichia coli , Staphylococcus aureus , L. monocytogenes and Salmonella among the four pathogenic bacteria detected in all samples were 4.3%, 3.3%; 3.0%; and 1.0%, respectively. This study can be used to qualitatively assess the microbiological quality associated with cold dishes. It provides data to support the detection of possible food safety problems.
The aim of the present study was to investigate the ability of natural plant-derivate (flavonoid compounds) products to reduce and/or inhibit the biofilm-forming ability of Listeria monocytogenes. A collection of 500 synthetic and natural flavonoids were tested on strains of L. monocytogenes for their antimicrobial and anti-biofilm activity. L. monocytogenes biofilm inhibition by flavonoid compounds was tested on i) stainless steel coupons using crystal violet staining and ii) glass slides using confocal laser scanning microscopic (CLSM) imaging. The flavonoids were tested against a L. monocytogenes cocktail of 5 strains at a concentration of 100 µM to determine their effect on planktonic growth. A total of 17 flavonoids were chosen for further study due to their ability to significantly reduce the growth of L. monocytogenes in BHI broth, while 2 flavonoids were chosen because they actually increased growth. A lower concentration of flavonoid compounds (50 µM) was selected to investigate their effects on L. monocytogenes biofilm formation using i) stainless steel coupons to quantify biomass and ii) glass coupons to observe the biofilm architecture. The 19 flavonoids showed various levels of L. monocytogenes growth inhibition, ranging from 2% to 100%, as compared to the respective positive and negative controls on stainless steel, after 48 h of incubation at 22 o C. In addition, in comparison to the control, most of the 19 flavonoids significantly (p ≤ 0.05) inhibited biofilm formation, with at least one of the L. monocytogenes strains or at one of the tested temperatures. In fact, when grown in BHI broth with 50 µM of the 19 selected flavonoid compounds for 48 h at 22 o C, there were visible reductions in L. monocytogenes biofilm formation on the glass coupons. Overall, we found multiple flavonoid compounds to be promising anti-biofilm and antimicrobial agents against L. monocytogenes .
The effects of the sodium alginate (SA) coating incorporated with cinnamon essential oil nanocapsules (CEO-NPs) and Nisin, as a new edible coating, were investigated on the preservation of beef slices in the refrigerated storage for 15 days. All beef samples were analyzed for physicochemical properties (pH value, weight loss, the total volatile base nitrogen (TVB-N)) and antimicrobial activity against total bacterial count (TBC). Besides, the changes in color parameters and sensory attributes of all beef samples were evaluated. The results revealed that the incorporation of the complex of CEO-NPs and Nisin retarded the growth of the microorganism and reduced lipid oxidation, as determined by pH, TVB-N, and TBC. This can extend the shelf life of beef slices to 15 days. Moreover, the treatment with the SA coating, incorporating CEO-NPs and Nisin, significantly improved the weight loss, color, odor, textural, and broth attributes of the beef samples. The results suggest that the coating treatment enriched with CEO-NPs and Nisin could significantly inhibit quality deterioration of beef slices, and the complex of CEO-NPs and Nisin can improve antioxidant, antibacterial and sensory properties of the SA coating. Thus, the new edible coating could be regarded as a potential material to preserve beef slices.
Salmonella continues to be a significant cause of foodborne illnesses in human medicine. The Centers for Disease Control and Prevention reported Salmonella as the second leading cause of foodborne illness in the United States, and the leading cause of both hospitalizations and deaths. Salmonella enterica 4,,12:i:- (STM) is a monophasic variant of S. Typhimurium and it is an emerging threat to both human and animal health. STM was first identified in the 1980’s from poultry products and has become increasingly prevalent in meat products including pork. STM has also been identified in swine farms as well as feed manufacturing environments and feed itself. Similar pulse-field gel electrophoresis profiles have been observed between human clinical cases and the STM samples originating from swine feed. These related profiles suggest a link between swine ingesting contaminated feed and the source of foodborne illness in human. The objective of this article was to better understand the history of STM and the possible pathway between swine feed to the household table. Continued research is necessary to better understand how STM can enter both the feed supply chain and the pork production chain to avoid contamination of pork products destined for human consumption.
Toxoplasma gondii is the causative agent of the parasitic disease toxoplasmosis, which is an important food borne zoonosis. Eating undercooked meat of infected animals has been considered the major transmission route of T. gondii to humans. The present study evaluates the efficacy of domestic freezing on the inactivation of T. gondii bradyzoites in raw and dry-cured ham. Meat (raw and dry-cured ham) of a pig experimentally orally inoculated with 4,000 oocysts of T. gondii VEG strain was subjected to domestic freezing of -20 ºC at different days. The effect was evaluated by bioassay in mice followed by qPCR. In raw ham and dry-cured ham, temperature of -20 ºC for 7 and 14 days respectively did not inactivate T. gondii . More studies are needed to find the right temperature and time needed to render the bradyzoites non-infectious for human. Meanwhile, the recommendations of freezing to inactivate T. gondii in raw or dry-cured meats must be revisited considered that it does not reduce the risk of infection.
Bacillus weihenstephanensis can grow at refrigeration temperature and cause food poisoning. It has been isolated from liquid whole egg products. The moderate heat used for pasteurization of liquid egg products is ineffective for killing spore-forming bacteria including Bacillus. Available predictive models and a pretrial study in broth suggested the potential for growth of Bacillus spp. under the tested conditions. Hence, hurdles such as storage of product below 4°C or use of preservatives would be needed to ensure the food safety of pasteurized egg products. This study evaluated the growth inhibition of B. weihenstephanensis in pasteurized liquid whole egg product formulated with 6.25 ppm nisin during storage at refrigerated and abuse refrigerated temperatures for a total 13 weeks, in three replicate trials. At day 0, the product had a pH of 7.52±0.29, while background microflora such as aerobic plate counts, presumptive B. cereus, and yeast and molds were <10 CFU/g. Product inoculated with target 2.5 log10 CFU/g of B. weihenstephanensis, stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks exhibited no growth in all three replicate trials. Average counts reduced (p<0.05) by at least one-log10 in six weeks in all samples stored at either 7 or 10°C. Similarly, growth of total plate counts, presumptive Bacillus spp., yeast and mold counts was not observed in uninoculated controls stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks. Visual and odor evaluation performed at each sampling time point showed no abnormalities. This study assessed the efficacy of maximum allowed level of nisin for use in pasteurized liquid whole eggs and validated the inhibition of B. weihenstephanensis in the product for an extended shelf life of up to 13 weeks.