Changes in the microbial communities of tiger frog (Rana tigrina) meat during refrigerated storage

Author(s):  
Dong Chen ◽  
Mingxin Ci ◽  
Runqiao Dai ◽  
Ronghui Chen ◽  
Tianping Li

Microbial activity is the major cause of the spoilage of aquatic meat products during storage. This study investigated the changes of the microbial compositions of the tiger frog (Rana tigrina) meat stored aerobically at 4 ℃ for 12 days using the 16S rRNA amplicon high throughput sequencing (HTS) analysis. The microbial diversity and species richness of the frog meat were abundant at the initial phase of storage but decreased substantially with the prolongation of the storage time. Proteobacteria was the prevalent phylum identified from the frog meat with a relative abundance of 40.29% at day 0 increasing to 96.77% at day 6 and 95.41% at day 12, respectively. At the genus level, Shewanella, Pseudomonas, and Acinetobacter were the three dominant genera in the spoiled samples and contributed to the frog meat spoilage. Their proportions were 41.67%, 28.48%, and 5.94% at day 6, and 29.94%, 23.48%, and 18.44% at day 12, respectively. The present study is conducive to understand the pattern and process of the frog meat spoilage during refrigeration and could be used to develop efficient control measures to mitigate the predominant psychrotrophic spoilers in the aerobically stored frog meat.

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinfu Li ◽  
Qiang Xiong ◽  
Hui Zhou ◽  
Baocai Xu ◽  
Yun Sun

Staphylococcus xylosus, Leuconostoc mesenteroides, Carnobacterium maltaromaticum, Leuconostoc gelidum, and Serratia liquefaciens were investigated for their roles in in the spoilage of sterilized smoked bacon. These five strains, individually and in combination, were applied as starters on sliced bacon at 4–5 log10 CFU/g using a hand-operated spraying bottle and stored for 45 days at 0–4°C. Dynamics, diversity, and succession of microbial community during storage of samples were studied by high-throughput sequencing (HTS) of the V3–V4 region of the 16S rRNA gene. A total of 367 bacterial genera belonging to 21 phyla were identified. Bacterial counts in all the inoculated specimens increased significantly within the first 15 days while the microbiota developed into more similar communities with increasing storage time. At the end of the storage time, the highest abundance of Serratia (96.46%) was found in samples inoculated with S. liquefaciens. Similarly, for samples inoculated with C. maltaromaticum and L. mesenteroides, a sharp increase in Carnobacterium and Leuconostoc abundance was observed as they reached a maximum relative abundance of 97.95 and 81.6%, respectively. Hence, these species were not only the predominant ones but could also have been the more competitive ones, potentially inhibiting the growth of other microorganisms. By analyzing the bacterial load of meat products using the SSO model, the relationships between the microbial communities involved in spoilage can be understood to assist further research.


Author(s):  
Julio César Castillo-Cuenca ◽  
Álvaro Martínez-Moreno ◽  
José Manuel Diaz-Cao ◽  
Angel Entrena-García ◽  
Jorge Fraga ◽  
...  

AbstractA cross-sectional study was carried out to determine the seroprevalence of Toxoplasma gondii and associated risk factors in pigs in the largest pork-producing region in Cuba. Serum samples from 420 pigs, including 210 sows and 210 post-weaning pigs, were tested for antibodies against T. gondii using a commercial indirect enzyme-linked immunosorbent assay. Anti-T. gondii antibodies were detected in 56 animals (13.3%, 95% CI: 10.1–16.6). A generalized estimating equations model revealed that the risk factors associated with higher seropositivity in pigs were altitude (higher in farm’s location < 250 m above sea level (masl) versus ≥ 250 masl) and age (higher in sows compared to post-weaning pigs). The results indicated that this protozoan parasite is widely distributed on pig farms in the study area, which is a public health concern since the consumption of raw or undercooked pork meat products containing tissue cysts is considered one of the main routes of T. gondii transmission worldwide. Control measures should be implemented to reduce the risk of exposure to T. gondii in pigs in Cuba.


Viruses ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 566 ◽  
Author(s):  
Siemon Ng ◽  
Cassandra Braxton ◽  
Marc Eloit ◽  
Szi Feng ◽  
Romain Fragnoud ◽  
...  

A key step for broad viral detection using high-throughput sequencing (HTS) is optimizing the sample preparation strategy for extracting viral-specific nucleic acids since viral genomes are diverse: They can be single-stranded or double-stranded RNA or DNA, and can vary from a few thousand bases to over millions of bases, which might introduce biases during nucleic acid extraction. In addition, viral particles can be enveloped or non-enveloped with variable resistance to pre-treatment, which may influence their susceptibility to extraction procedures. Since the identity of the potential adventitious agents is unknown prior to their detection, efficient sample preparation should be unbiased toward all different viral types in order to maximize the probability of detecting any potential adventitious viruses using HTS. Furthermore, the quality assessment of each step for sample processing is also a critical but challenging aspect. This paper presents our current perspectives for optimizing upstream sample processing and library preparation as part of the discussion in the Advanced Virus Detection Technologies Interest group (AVDTIG). The topics include: Use of nuclease treatment to enrich for encapsidated nucleic acids, techniques for amplifying low amounts of virus nucleic acids, selection of different extraction methods, relevant controls, the use of spike recovery experiments, and quality control measures during library preparation.


2019 ◽  
Vol 3 (2) ◽  
Author(s):  
E. Heintz ◽  
K. Glass ◽  
J. Lim

ObjectivesWorld’s largest outbreak of listeriosis in South Africa last year, remind us that Listeria monocytogenes contamination and growth is still of major concern in refrigerated RTE meats. The same time customers demand for clean label food safety solutions. Provian NDV, a fermented vinegar based powder, was developed to provide a clean label solution that inhibits Listeria monocytogenes during long term refrigerated storage. This document describes the effect of chemical derived acetates and Provian NDV, a novel vinegar based product, on the inhibition of Listeria monocytogenes in a cooked meat applicationMaterials and MethodsFive treatments of cured deli-style ham were tested. The pork ham contained 72–74% (w/w) moisture, 1.75 ± 0.1% (w/w) salt, and pH 6.2–6.4, 156 mg/kg sodium nitrite and 547 mg/kg sodium erythorbate. The treatments included a control without antimicrobials and different concentrations of a chemically derived acetates (0.5% and 0.75%) and Provian® NDV (0.5%, 0.65%). Cooked products were surface-inoculated with 3-log10 CFU/g of a cocktail of 5 strains of Listeria monocytogenes from the culture collection of Food research institute, Wisconsin University including serotypes 4b, 1/2a, and 1/2b. All strains were isolated from RTE- cooked meat products. Inoculated slices (100 g/package) were vacuum-packaged and stored at 4°C and 7°C for 8 to 12 wk. Per treatment triplicate samples were assayed by enumerating on modified Oxford Agar. One way ANOVA was used to analyze significance, p < 0.05. Except from the triplicate repeat, this study was conducted twice independently (trial 1, 5 treatments in triplicate and trial 2 including same treatments, also in triplicate.)ResultsControl Ham supported > 1 log increase of L. monocytogenes at 4- and 2-weeks storage at 4 and 7°C, respectively. In contrast, hams supplemented with 0.5 or 0.75% chemical acetates or 0.65% Provian® NDV inhibited the Listeria growth for 12 and 8 wk at 4 and 7°C, respectively. Inhibition of Listeria on ham supplemented with 0.5% Provian®NDV was further affected by pH and moisture. Ham supplemented with 0.5% Provian® NDV in the trial 1 (71.5% moisture, pH 6.2) delayed Listeria for 12 wk storage at 4°C, whereas individual samples of trial 1 (72.9% moisture, pH 6.3) supported growth (> 1 log increase) at 8 wk. Similar trends were observed at 7°C. The images below reflect the results of trial 1 only.ConclusionThis study confirms the efficacy of acetates on the inhibition of Listeria monocytogenes. Next, this study shows that a product based on natural fermented vinegar, Provian NDV, has a comparable growth inhibitive action in a cured ready-to eat ham. This illustrates that most relevant serotypes (4b, 1/2b and 1/2a) of Listeria moncytogenes can be controlled using an ingredient based on natural fermented vinegar.Figure 4.


Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4128
Author(s):  
Olaf K. Horbańczuk ◽  
Małgorzata Moczkowska ◽  
Joanna Marchewka ◽  
Atanas G. Atanasov ◽  
Marcin A. Kurek

Ostrich meat is a high-quality dietetic product, however, it is very sensitive to deterioration during storage. The aim of this study was to assess the effect of packaging systems on the fatty acid (FA) profiles in ostrich meat during refrigerated storage. The systems were: Vacuum packaging (VP) and modified atmosphere packaging (MAP) in two combinations of gases: MAP1 (40% O2/40% CO2/20% N2) and MAP2 (60% O2/30% CO2/10% N2). Samples were taken from the M. ilifibularis (IF) muscles of eight ostriches in each treatment group. The packs were stored in a refrigerator at 2 °C and analyzed at 0, 4, 8, 12 and 16 days. The packaging conditions and storage time had an impact on the concentration of bioactive compounds such as polyunsaturated fatty acids (PUFA), including n-3 such as C18:3, C20:5 (EPA) and C22:6 (DHA). The least changes in composition of n-3 and the sum of PUFA were recorded in ostrich meat packaged in vacuum, followed by that packaged using MAP1 and MAP2. The sum of n-6 PUFAs decreased significantly by 2.1% for MAP2, and only by 0.7% for vacuum packaging as the experiment progressed. A significant deterioration of these compounds was observed in all package systems, especially from day 12 until day 16 of storage.


2011 ◽  
Vol 74 (6) ◽  
pp. 990-993 ◽  
Author(s):  
BRENDAN A. NIEMIRA

Contamination of tomatoes with Salmonella is a recurring food safety concern. Irradiation is a nonthermal intervention that can inactivate pathogens on fresh and minimally processed produce. However, the influence of tomato processing protocols, including time in refrigerated storage and time between slicing and irradiation, has not been determined. Roma tomatoes were sliced and inoculated with a cocktail of Salmonella outbreak strains. The inoculated tomatoes were held in refrigerated storage for various times after inoculation to simulate the potential time delay between packaging and irradiation. Tomatoes were irradiated immediately (0 h) or after 24, 48, or 72 h in storage. The surviving populations were recovered and enumerated. Irradiation effectively reduced Salmonella at all times. The D10-values (the dose necessary for a 1-log reduction of the pathogen) were not significantly different at each storage time and ranged from 0.382 to 0.473 kGy. These results suggest that the time required for holding of processed Roma tomatoes or shipment to an off-site irradiation service provider will not alter the efficacy of irradiation in a commercial environment.


Author(s):  
Na Li ◽  
Chong Liu ◽  
Zhiguo Zhang ◽  
Hongna Li ◽  
Tingting Song ◽  
...  

The extensive use of antimicrobials in animal farms poses serious safety hazards to both the environment and public health, and this trend is likely to continue. Antimicrobial resistance genes (ARGs) are a class of emerging pollutants that are difficult to remove once introduced. Understanding the environmental transfer of antimicrobial-resistant bacteria (ARB) and ARGs is pivotal for creating control measures. In this review, we summarize the research progress on the spread and detection of ARB and ARG pollution related to animal husbandry. Molecular methods such as high-throughput sequencing have greatly enriched the information about ARB communities. However, it remains challenging to delineate mechanisms regarding ARG induction, transmission, and tempo-spatial changes in the whole process, from animal husbandry to multiple ecosystems. As a result, future research should be more focused on the mechanisms of ARG induction, transmission, and control. We also expect that future research will rely more heavily on metagenomic -analysis, metatranscriptomic sequencing, and multi-omics technologies


2011 ◽  
pp. 269-278 ◽  
Author(s):  
Milos Kapetanov ◽  
Dubravka Potkonjak ◽  
Dubravka Milanov ◽  
Igor Stojanov ◽  
Milica Zivkov-Balos ◽  
...  

Fungi belonging to genus Aspegillus are ubiquitous saprophytic microorganisms which are, in certain circumstances, responsible for clinical infections of respiratory tract in all poultry, particularly in young birds. In case of a lung form, Aspergillus fumigatus, A. niger and A. glaucus are the most frequently isolated fungi. In general, poultry is constantly exposed to these fungi in its environment. Predisposing factors, such as long exposition and highly contaminated environment and litter, high humidity in poultry houses, poor ventilation, malnutrition and stress, all contribute to clinical aspergillosis. Some geographic and seasonal regularities are observed in relation to the distribution of disease outbreaks. In this sense, cases of aspergillosis in our country were more frequently noted in wild areas located northern from the rivers Sava and Danube. Influence of some factors on the outbreak and spreading, as well as predominant clinical features of aspergillosis in poultry were investigated in this paper. Possible prophylactic and intervention measures were discussed. The occurrence of Aspergillus sp. in poultry was analyzed according to the clinical and laboratory investigations performed during the two selected years, 2000 and 2010. Widespread aspergillosis was noted in poultry flocks of different age, both in young and adult birds. During the years 2000 and 2010, acute aspergillosis was found in 12 and 16 commercial flocks of chickens and turkeys, respectively. Ocular infection with Aspergillus was determined in 10 day old broilers from two flocks. Aspergillus sp. was isolated from unhatched eggs (6.86%), litter (23.07%), environmental (36.17%) and hatchery swabs (3.85%). Besides the appropriate antifungal therapy, enforcement of proper sanitary-hygiene measures on poultry farms and hatcheries, as well as microbiological control of feed are considered essential for an efficient control of infection and its spreading.


1995 ◽  
Vol 58 (1) ◽  
pp. 70-75 ◽  
Author(s):  
L. M. MEDINA ◽  
R. JORDANO

Seventy samples from two batches of commercially produced fermented milk were analyzed for constitutive microbiota. Five samples were tested on the day of collection and the others analyzed after 10, 17, 24, 28, 31 and 36 days of storage at 7°C. M17 agar was used to enumerate Streptococcus salivarius subsp. thermophilus. MRS (de Man, Rogosa, Sharpe) agar was used to enumerate Lactobacillus acidophilus. For the enumeration of Bifidobacterium spp. MRS agar to which antibiotic substances were added was used. In the case of Batch A, streptococci, lactobacilli and bifidobacteria were initially present at levels of 231.2 × 106, 0.677× 106 and 1.558 × 106, respectively. The initial pH of 4.48 decreased to 4.12 after 24 days. For Batch B, streptococci, lactobacilli and bifidobacteria were initially present at levels of 858 × 106, 190.7 × 106 and 1.644 × 106, respectively. The initial pH of 4.23 decreased to 4.07 and 3.84 after 24 and 36 days, respectively. The fall in the counts throughout refrigerated storage time showed some irregularities which, in our opinion, indicate a lack of control over the ecological aspects which affect the interrelation between the microorganisms involved. The statistical significance of the differences between the different trials was established throughout the time.


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