Incidence, Radioresistance, and Behavior of Psychrobacter spp. in Rabbit Meat

2005 ◽  
Vol 68 (3) ◽  
pp. 538-543 ◽  
Author(s):  
JOSÉ M. RODRÍGUEZ-CALLEJA ◽  
MARGARET F. PATTERSON ◽  
ISABEL GARCÍA-LÓPEZ ◽  
JESÚS A. SANTOS ◽  
ANDRÉS OTERO ◽  
...  
Keyword(s):  
Similar Increase ◽  
Chilled Storage ◽  
Relative Incidence ◽  
Spoilage Bacteria ◽  
Brochothrix Thermosphacta ◽  
Pure Cultures ◽  
Maximum Cell ◽  
Rabbit Meat ◽  
Cell Densities ◽  
And Behavior

The relative incidence of Psychrobacter spp. in rabbit meat, the radioresistance of these bacteria, and the growth of nonirradiated and irradiated psychrobacter isolates, alone and in coculture, during chilled storage of inoculated sterile rabbit meat was investigated. Psychrobacter spp. accounted for 4.2% of the storage psychrotrophic flora of 30 rabbit carcasses. The radiation D10-values of 10 Psychrobacter isolates, irradiated at 4°C in minced rabbit meat, ranged from 0.8 to 2.0 kGy, with significant (P < 0.05) differences among strains. Over 12 days of storage at 4°C, pure cultures of two nonirradiated psychrobacter strains (D10 = 2 kGy) were capable of substantial increases (up to 3 log CFU/g) in sterile rabbit meat, but when the fastest growing strain was cocultured with Pseudomonas fluorescens and Brochothrix thermosphacta isolates, maximum cell densities and growth rates were significantly (P < 0.01) lower. After irradiation (2.5 kGy) of pure cultures in sterile rabbit meat, surviving cells of both Psychrobacter strains decreased for a period of 5 to 7 days and then resumed multiplication that, at day 12, resulted in a similar increase (1.6 to 1.7 log CFU/g) over initial survivor numbers. When irradiated in combination with the spoilage bacteria, one of the strains required 12 days to reach initial numbers. In conclusion, Psychrobacter spp. are radioresistant nonsporeforming bacteria with a low relative incidence among the storage flora of rabbit meat, unable to compete with food spoilage bacteria in this ecosystem and apparently not a major contributor to the spoilage of rabbit meat after irradiation.

Land-fast ice microalgal and phytoplanktonic communities (Adélie Land, Antarctica) in relation to environmental factors during ice break-up

2003 ◽  
Vol 15 (3) ◽  
pp. 353-364 ◽  
Author(s):  
C. RIAUX-GOBIN ◽  
M. POULIN ◽  
R. PRODON ◽  
P. TREGUER
Keyword(s):  
Sea Ice ◽  
Early Spring ◽  
Ice Melt ◽  
Fast Ice ◽  
Maximum Cell ◽  
Cell Densities ◽  
Ice Water ◽  
Water Species ◽  
Very High ◽  
Pennate Diatoms

Annual land-fast ice, particularly an unconsolidated layer or “platelet ice-like” layer (PLI), was sampled in spring 1995 to study the spatial and short-term variations of ice-associated diatoms. Under-ice water, a lead and small polynyas were also sampled. Along a 7 km seaward transect a geographical gradient was evident, with some rare diatom species present only in the offshore PLI, whereas others (mainly pennate diatoms) were ubiquitous. The dense microphytic PLI community as well as the phytoplankton was diatom-dominated, but, within these two communities, marked differences appeared. First, the sea-ice communities (PLI and solid bottom ice) were moderately diverse (36 species), mostly composed of pennate diatoms, of which many were chain forming or tube-dwelling. Dominant taxa were Navicula glaciei, Berkeleya adeliensis, Nitzschia stellata, Amphiprora kufferathii and Nitzschia lecointei. Some differences in the distribution of the most dominant species appeared within the bottom ice and the PLI, attesting to differences in the origin or/and growing capability of these diatoms in these two ice compartments. Under-ice water species composition was mixed with sea-ice communities only on the most coastal sites and during ice melt. Maximum cell numbers were mostly noticed in the PLI, reaching up to 1010 cells l−1 and very high Chl a concentrations (exceptionally up to 9.8 mg Chl a l−1 or 1.9 g Chl a m−2, from a 10 to 20 cm thick PLI layer, close to the continent). Secondly, the phytoplankton in the lead and small polynyas had a low diversity, very low standing stocks (on an average 0.69 μg Chl a l−1) and cell densities (2 × 104 cells l−1). Some species from the polynyas were similar to those of the PLI, such as Navicula glaciei, but others were typically planktonic, such as Chaetoceros cf. neglectus. The presence of encysted cells (Chaetoceros and Chrysophytes) was also noticeable in the polynya water. In early spring no seeding process was obvious from the PLI to polynya water. A comparison with similar fast-ice diatom communities in other parts of coastal Antarctica, is presented.

Effect of Single or Sequential Hot Water and Lactic Acid Decontamination Treatments on the Survival and Growth of Listeria monocytogenes and Spoilage Microflora during Aerobic Storage of Fresh Beef at 4, 10, and 25°C

2004 ◽  
Vol 67 (12) ◽  
pp. 2703-2711 ◽  
Author(s):  
KONSTANTINOS P. KOUTSOUMANIS ◽  
LAURA V. ASHTON ◽  
IFIGENIA GEORNARAS ◽  
KEITH E. BELK ◽  
JOHN A. SCANGA ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Hot Water ◽  
Microbial Profile ◽  
Spoilage Bacteria ◽  
Brochothrix Thermosphacta ◽  
Survival And Growth ◽  
Spoilage Microflora ◽  
Storage Temperatures

The survival and growth of Listeria monocytogenes and spoilage microflora during storage of fresh beef subjected to different decontamination treatments was studied. Fresh beef inoculated with a five-strain mixture of L. monocytogenes (5.18 log CFU/cm2) was left untreated (control) or was immersed (30 s) in hot water (HW; 75°C), 2% lactic acid (LA; 55°C), hot water followed by lactic acid (HW-LA), or lactic acid followed by hot water (LA-HW) and then stored aerobically at 4, 10, and 25°C for 25, 17, and 5 days, respectively. Initial populations of L. monocytogenes were reduced by 0.82 (HW), 1.43 (LA), 2.73 (HW-LA), and 2.68 (LA-HW) log CFU/cm2. During storage, the pathogen grew at higher rates in HW than in control samples at all storage temperatures. Acid decontamination treatments (LA, HW-LA, and LA-HW) resulted in a weaker inhibition of L. monocytogenes (P < 0.05) at 25°C than at 4 and 10°C. In general, the order of effectiveness of treatments was HW-LA > LA > LA-HW > HW > control at all storage temperatures tested. In untreated samples, the spoilage microflora was dominated by pseudomonads, while lactic acid bacteria, Enterobacteriaceae, and yeasts remained at lower concentrations during storage. Brochothrix thermosphacta was detected periodically in only a limited number of samples. Although decontamination with HW did not affect the above spoilage microbial profile, acid treatments shifted the predominant microflora in the direction of yeasts and gram-positive bacteria (lactic acid bacteria). Overall, the results of the present study indicate that decontamination with LA and combinations of LA and HW could limit growth of L. monocytogenes and inhibit pseudomonads, which are the main spoilage bacteria of fresh beef stored under aerobic conditions. However, to optimize the efficacy of such treatments, they must be applied in the appropriate sequence and followed by effective temperature control.

Microbiological Changes in Pressurized, Prepackaged Sliced Cooked Ham

1999 ◽  
Vol 62 (12) ◽  
pp. 1411-1415 ◽  
Author(s):  
M. E. LÓPEZ-CABALLERO ◽  
J. CARBALLO ◽  
F. JIMÉNEZ-COLMENERO
Keyword(s):  
High Pressure ◽  
Processing Time ◽  
Microbiological Quality ◽  
Viable Count ◽  
Pressure Level ◽  
Binding Properties ◽  
Water Binding ◽  
Chilled Storage ◽  
Cooked Ham ◽  
Brochothrix Thermosphacta

This was a study of the influence of high-pressure conditions (200 and 400 MPa, 5 and 20 min, 7°C) on microbiological quality and water-binding properties of vacuum-prepackaged sliced cooked ham and how this affects microbiological changes during chilled storage (2°C). Pressurization caused a degree of microbiological inactivation, which increased with pressure level and processing time. Pressurization at 400 MPa significantly reduced the total viable count and lactic acid bacteria to the extent that after 20 min no Enterobacteriaceae, Baird Parker flora, or Brochothrix thermosphacta were detected throughout any of the chilled storage periods studied. In general, gram-positive flora was more resistant to pressure than gram-negative flora. The fact that high pressure (400 MPa) causes considerable inactivation of microorganisms could be used to prolong the shelf life of vacuum-prepackaged sliced cooked ham.

scholarly journals Applicability of an Arrhenius Model for the Combined Effect of Temperature and CO2 Packaging on the Spoilage Microflora of Fish

2000 ◽  
Vol 66 (8) ◽  
pp. 3528-3534 ◽  
Author(s):  
Konstantinos P. Koutsoumanis ◽  
Petros S. Taoukis ◽  
Eleftherios H. Drosinos ◽  
George-John E. Nychas
Keyword(s):  
Growth Rates ◽  
Modified Atmosphere Packaging ◽  
Energy Parameter ◽  
Effect Of Temperature ◽  
Arrhenius Model ◽  
Spoilage Bacteria ◽  
Brochothrix Thermosphacta ◽  
Natural Microflora ◽  
Spoilage Microflora ◽  
Mediterranean Fish

ABSTRACT The temperature behavior of the natural microflora on the Mediterranean fish red mullet (Mullus barbatus) was examined as a case study. The growth of the spoilage bacteriaPseudomonas spp., Shewanella putrefaciens,Brochothrix thermosphacta, and lactic acid bacteria was modeled as a function of temperature and the concentration of carbon dioxide in modified atmosphere packaging. Combined models were developed and comparatively assessed based on polynomial, Belehradek, and Arrhenius equations. The activation energy parameter of the Arrhenius model, EA , was independent of the packaging atmosphere and ranged from 75 to 85 kJ/mol for the different bacteria, whereas the preexponential constant decreased exponentially with the packaging CO2 concentration. We evaluated the applicability of the models developed by using experimental bacterial growth rates obtained from 42 independent experiments performed with three Mediterranean fish species and growth rates predicted from the models under the same temperature and packaging conditions. The accuracy factor and bias factor were used as statistical tools for evaluation, and the developed Arrhenius model and the Belehradek model were judged satisfactory overall.

Chemical Inhibition of Growth of Fish Spoilage Bacteria

1944 ◽  
Vol 6c (3) ◽  
pp. 257-266 ◽  
Author(s):  
H. L. A. Tarr
Keyword(s):  
Fish Muscle ◽  
Ethyl Formate ◽  
Ethylene Dichloride ◽  
Sodium Chlorite ◽  
Inhibition Of Growth ◽  
Fish Spoilage ◽  
Spoilage Bacteria ◽  
Pure Cultures ◽  
Chloramine T ◽  
Chemical Inhibition

Inhibition of the growth of fish spoilage bacteria in naturally contaminated fish muscle, and in some instances of pure cultures of such organisms cultivated on laboratory media, by penicillic acid, 4-methoxy-2:5 toluquinone, methyl formate, ethyl formate, ethylene oxide, propylene oxide, methyl ether, ethyl ether, chloroform, ethylene dichloride, ethyl chloride, 1:4 dioxane, Chloramine B, Chloramine T, a mixture of isomeric glycerol formais, sodium chlorite, sodium benzoate, sodium nitrite, and one patent fish preservative was investigated. The results are discussed and are summarized in detail.

Influence of microbial flora on xylose absorption in rats and mice

1963 ◽  
Vol 205 (3) ◽  
pp. 417-420 ◽  
Author(s):  
James B. Heneghan
Keyword(s):  
Microbial Flora ◽  
Similar Increase ◽  
Twofold Increase ◽  
Absorption Studies ◽  
Pure Cultures ◽  
Significant Change ◽  
Rats And Mice ◽  
Germfree Rats

The absence of a microbial flora produced a twofold increase in the absorption of d-xylose in germfree mice as determined by the everted sac technique. The existence of a similar increase was confirmed in germfree rats by using one in vitro and two in vivo techniques. Monocontamination of germfree mice with pure cultures of microorganisms also produced changes in xylose absorption. Studies on water, Na+, and K+ absorption in germfree mice indicated that the flora produces no significant change in the absorption of Na+ or in the movement of water and K+.

scholarly journals Microbial Safety of Black Summer Truffle Collected from Sicily and Umbria Regions, Italy

2021 ◽  
Author(s):  
F. Cirlincione ◽  
N. Francesca ◽  
L. Settanni ◽  
D. Donnini ◽  
G. Venturella ◽  
...  
Keyword(s):  
Central Italy ◽  
Microbial Populations ◽  
Fecal Indicators ◽  
Tuber Aestivum ◽  
Spoilage Bacteria ◽  
The Common ◽  
Cell Densities ◽  
Microbial Risks ◽  
Microbial Groups ◽  
Yeasts And Molds

Background: Tuber aestivum Vittad., known as black summer truffle, represents high-value food especially used as garnishment in nouvelle cuisine. The aim of this study was to investigate on the viable microbial populations associated with T. aestivum ascomata collected in different sites of Sicily and one locality of Umbria (Italy). Methods: The ripe ascomata of black summer truffles were collected from Central Italy. Cell densities of spoilage bacteria, fecal indicators, potential pathogens, yeasts, and molds were analyzed. Statistical analysis was conducted with XLSTAT software. Results: The microbiological counts of truffles ranged between 6.00 and 9.63 log Colony Forming Unit (CFU)/g for total mesophilic count and between 6.18 and 8.55 log CFU/g for total psychrotrophic count; pseudomonads were in the range 6.98-9.28 log CFU/g. Listeria spp. and coagulase-positive streptococci detected in no samples. Coagulase-negative streptococci were found in some samples with 2.11-4.76 log CFU/g levels. Yeasts and filamentous fungi were detected at consistent levels of 3.60-7.81 log CFU/g. Significant differences (p<0.01) were found between samples and also for all microbial groups. Conclusion: This study evidenced that the common brushing procedure applied for preparation of truffles is not sufficient to eliminate microbial risks for consumers. The application of an efficient decontamination treatment is strongly suggested before consumption of fresh truffles.

Enumeration of Meatborne Spoilage Bacteria with Hydrophobic Grid Membrane Filtration†

1997 ◽  
Vol 60 (11) ◽  
pp. 1388-1390 ◽  
Author(s):  
G. GORDON GREER ◽  
BRYAN D. DILTS
Keyword(s):  
Membrane Filtration ◽  
Pseudomonas Sp ◽  
Bacterial Group ◽  
Psychrotrophic Bacteria ◽  
Lactobacillus Sake ◽  
Spoilage Bacteria ◽  
Brochothrix Thermosphacta ◽  
Plate Counts ◽  
Conventional Plate ◽  
Escherichia Coli B

Hydrophobic grid membrane filtration (HGMF) was investigated as an alternative to conventional plate counts for enumerating spoilage bacteria recovered from raw beef. The HGMF method was compared to conventional procedures for the selective enumeration of total psychrotrophic bacteria, pseudomonads, total Enterobacteriaceae. Brochothrix thermosphacta, and lactic acid bacteria. Bacteria were recovered both from beef which had been artificially inoculated with identified strains and from naturally contaminated beef from a commercial abattoir. There were no significant differences (P &gt; 0.05) in numbers of any bacterial group recovered from naturally contaminated beef using HGMF procedures when compared to conventional plating on selective media. The recoveries of the total psychrotrophic population, Escherichia coli. B. thermosphacta, and Lactobacillus sake inoculated onto meat were unaffected by the enumeration procedure (P &gt; 0.05). However, the populations of Pseudomonas sp. recovered from inoculated beef by a HGMF procedure were 0.8 log cycles lower (P &lt; 0.05) when compared to the conventional spread plate procedure.

Survival and Growth of Wild-Type and rpoS-Deficient Salmonella Newport Strains in Soil Extracts Prepared with Heat-Treated Poultry Pellets

2019 ◽  
Vol 82 (3) ◽  
pp. 501-506 ◽  
Author(s):  
MANOJ K. SHAH ◽  
RHODEL BRADSHAW ◽  
ESMOND NYARKO ◽  
PATRICIA D. MILLNER ◽  
DEBORAH NEHER ◽  
...  
Keyword(s):  
Wild Type ◽  
Soil Extracts ◽  
Nonsterile Soil ◽  
Unamended Soil ◽  
Salmonella Newport ◽  
Heat Treated ◽  
Maximum Cell ◽  
Survival And Growth ◽  
Cell Densities ◽  
Amended Soil

ABSTRACT Manure runoff can transfer pathogens to farmlands or to water sources, leading to subsequent contamination of produce. Untreated biological soil amendments, like manure, can be contaminated with foodborne pathogens, such as Salmonella Newport, which may lead to transfer of the pathogen to fruits or vegetables. Studies have reported the occurrence and survival of Salmonella in manure or manure slurries. However, data on the survival and growth of Salmonella Newport is lacking in matrices simulating runoff. We quantified the survival and growth of wild-type (WT) Salmonella Newport and rpoS-deficient (ΔrpoS) strains in sterile and nonsterile soil extracts prepared with (amended) or without (unamended) heat-treated poultry pellets at 25°C. Salmonella Newport WT and ΔrpoS populations reached a maximum cell density of 6 to 8 log CFU/mL in 24 to 30 h in amended and unamended soil extracts and remained in stationary phase for up to 4 days. Salmonella Newport in amended soil extracts exhibited a decreased lag phase (λ, 2.87 ± 1.01 h) and greater maximum cell densities (Nmax, 6.84 ± 1.25 CFU/mL) compared with λ (20.10 ± 9.53 h) and Nmax (5.22 ± 0.82 CFU/mL) in unamended soil extracts. In amended soil extract, the ΔrpoS strain had no measurable λ, similar growth rates (μmax) compared with WT, and a lower Nmax compared with the WT strain. Unamended, nonsterile soil extracts did not support the growth of Salmonella Newport WT and led to a decline in populations for the ΔrpoS strain. Salmonella Newport had lower cell densities in nonsterile soil extracts (5.94 ± 0.95 CFU/mL) than it did in sterile soil extracts (6.66 ± 1.50 CFU/mL), potentially indicating competition for nutrients between indigenous microbes and Salmonella Newport. The most favorable growth conditions were provided by amended sterile and nonsterile soil extracts, followed by sterile, unamended soil extracts for both Salmonella Newport strains. Salmonella Newport may grow to greater densities in amended extracts, providing a route for increased Salmonella levels in the growing environments of produce.

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