Aims
The control of Listeria monocytogenes biofilm formation using lactocin AL705 bacteriocin at sub‐minimum inhibitory concentrations (MICs) through an antiquorum sensing strategy, was preliminarily ...investigated.
Methods and Results
The screening for biofilm formation of different Listeria species at 10°C allowed selecting L. monocytogenes FBUNT for its use as biofilm producer. MIC and minimum bactericidal concentration of lactocin AL705 purified extract against the pathogen was determined. Bacteriocin sub‐MICs were used to evaluate biofilm reduction. Concentrations between 2·5–20 AU ml−1 of lactocin AL705 produced significant decreases in biofilm formation without affecting the growth of the pathogen after 3 days of incubation. When bacteriocin concentrations (5–20 arbitrary units per millilitre (AU ml−1)) were investigated as quorum sensing (QS) inhibitors using Vibrio harveyi as reporter strain, a significant reduction in luminescence by lactocin AL705 (20 AU ml−1) was observed. Even when L. monocytogenes produced AI‐2 like molecules as recognized by the reporter strain, bacteriocins did not interfere with this compound.
Conclusion
Antilisterial lactocin AL705 used to disrupt QS through a signal molecule inactivation was able to control L. monocytogenes FBUNT biofilm formation. Other molecule(s) different from the AI‐2 involved during biofilm formation could be acting as target of the bacteriocin.
Significance and Impact of the Study
The use of bacteriocins derived from food‐grade micro‐organisms as a QS inhibition represents an effective strategy to control pathogens as well as an environmentally friendly sanitation method to mitigate postprocessing food contamination.
Several lactic acid bacteria (LAB) associated with meat products are important natural bacteriocin producers. Bacteriocins are proteinaceous antagonistic substances that are important in the control ...of spoilage and pathogenic microorganisms. The use of LAB as bioprotective cultures to extend the shelf life of fresh meat can improve microbial stability and safety in commercial meat preservation. Lactobacillus curvatus CRL705 used as a protective culture in fresh beef is effective in inhibiting Listeria innocua and Brochothrix thermosphacta as well as the indigenous contaminant LAB, retaining its inhibitory effect at low temperatures and having a negligible effect on meat pH. In addition to the hurdle represented by low temperature and vacuum-packaging, the use of live cells of Lb. curvatus CRL705 seems more feasible from an economic point of view – and without legal restrictions – compared to the addition of purified bacteriocins. A description of meat-borne bacteriocins and their application in meat to extend shelf life is discussed.
Lactobacillus curvatus CRL705 was examined for its effectiveness as protective culture in the biopreservation of vacuum-packaged fresh beef stored during 60
days at 2
°C. For this purpose,
L. ...curvatus CRL705, producer of lactocin 705 and lactocin AL705, was inoculated on the meat surface (10
6
cfu
g
−1). This microorganism became the dominating population throughout the storage period controlling the growth of
Brochothrix thermosphacta and spoilage lactic acid bacteria naturally present on the meat. When the microstructural characteristics of the meat were evaluated using light microscopy, beef samples inoculated with the bioprotective culture showed a 10
days delay for the appearance of tissue degradation signs. Sensory analysis demonstrated that beef samples treated with
L. curvatus CRL705 only developed an “acid” off-flavor after 60
days of refrigerated storage, and no undesirable off-odors were found. Therefore, inoculation with this bacteriocinogenic strain would provide an additional hurdle to improve storage life of refrigerated vacuum-packaged beef without affecting its sensory and structural characteristics.
The recent successful development of monoclonal antibodies that target key components of biological pathways has expanded the armamentarium of treatment options for patients with colorectal cancer ...(CRC). In particular, the epidermal growth factor receptor (EGFR), a tyrosine kinase growth factor receptor involved in CRC development and progression, is exploited by the newest monoclonal antibody that is available for use in CRC patients. Cetuximab, the first chimeric monoclonal antibody, which has been generated against the EGFR, is currently registered in USA, Europe and worldwide, in combination with irinotecan in the treatment of metastatic CRC patients who have progressed on irinotecan containing chemotherapy. Cetuximab is well tolerated and does not exacerbate the toxicity of concomitant chemotherapy. Furthermore, a series of phase III clinical trials are currently evaluating the combination of cetuximab with standard chemotherapy regimens in the first-line treatment chemotherapy-naïve patients with metastatic CRC.
To evaluate the inhibition effectiveness of Lactobacillus curvatus CRL705 used as a bioprotective culture and of its bacteriocins, lactocin 705 and lactocin AL705, against Listeria innocua, ...Brochothrix thermosphacta and indigenous lactic acid bacteria (LAB) in vacuum-packaged meat stored at 2°C. The live culture of Lact. curvatus CRL705 as well as synthetic lactocin 705 and purified lactocin AL705 were shown to be similarly effective in preventing the growth of B. thermosphacta and L. innocua in meat discs in contrast to control samples in which these micro-organisms grew rapidly, their numbers increasing by 3·0- and 2·1-log cycles respectively. In addition, indigenous LAB population showed a lower growth rate in the presence of lactocin 705. Bacteriocin activity was detected in the meat discs during 36 days at 2°C irrespective of the biopreservation strategy applied. Changes in pH were not significantly different in meat discs treated with the protective culture when compared with control samples. Lactobacillus curvatus CRL705 and the produced bacteriocins, lactocin 705 and lactocin AL 705, were effective in inhibiting L. innocua and B. thermosphacta. The use of the bioprotective culture in refrigerated vacuum-packaged fresh meat would be more feasible from an economic and legal point of view. Establishment of biopreservation as a method to ensure the microbiological safety of vacuum-packaged fresh meat at 2°C.
Objectives
The objective of this study was to evaluate the ability of
Lactobacillus curvatus
CRL705, CRL1532, and CRL1533 and
Lactobacillus sakei
CRL1613 to survive under simulated gastrointestinal ...conditions. Moreover, a microencapsulation approach was proposed to improve gastrointestinal survival. Finally, experiments were performed to demonstrate that
Lactobacill
us spp. can modulate the ability of
Listeria monocytogenes
FBUNT to adhere to and invade Caco-2 cells.
Results
Lactobacillus
strains were encapsulated in alginate beads to enhance the survival of bacteria under in vitro gastrointestinal conditions. All strains hydrolyzed bile salts using chenodeoxycholic acid as a substrate and adhered to Caco-2 cells. Cell-free supernatants (CFSs) showed antimicrobial activity against
L. monocytogenes
as demonstrated by agar diffusion assays. The average percentages of
L. monocytogenes
adhesion decreased from 67.74 to 41.75 and 38.7% in the presence of 50 and 90% (v/v), respectively, for all CFSs tested. The highest concentrations of CFSs completely inhibited the
L. monocytogenes
invasion of Caco-2 cells.
Conclusions
The studied
Lactobacillus
strains have protective effects against the adhesion and invasion of
L. monocytogenes
FBUNT. Alginate encapsulation of these bacteria improved gastrointestinal tolerance such that they could be further studied as potential probiotics against intestinal pathogenic bacteria.
A Geographic Information System (GIS) was used to estimate the technically available woody biomass from forests and willow biomass crops within a 40
km radius of Syracuse and Tupper Lake, NY. Land ...cover and land use data were used to identify the available land base and restrictions were applied for slope, parcel size and designated wetlands. Approximately 222,984 oven-dry tonnes (odt) of forest biomass are technically available annually around Syracuse, from 165,848 hectares (ha) of timberland. There are 67,880
ha of agricultural land technically available for growing willow biomass crops, which could produce 38,181
odt
yr
−1 if 5% of this land was used and yields were 11.25
odt
ha
−1
yr
−1. There are approximately 215,300
odt of forest biomass technically available annually around Tupper Lake from 211,500
ha of timberland. There are 781
ha of technically available agricultural land in this area so willow biomass production would be minimal. While these two areas have different land cover and land use characteristics, both have the potential to produce significant amounts of woody biomass.
The aim of the study was to assess the toxicity and the clinical activity of biweekly oxaliplatin in combination with infusional 5-fluorouracil (5-FU) and folinic acid (FA) administered every 2 weeks ...(FOLFOX-4 regimen) in patients with advanced gastric cancer (AGC). A total of 61 previously untreated AGC patients were treated with oxaliplatin 85 mg m(-2) on day 1, FA 200 mg m(-2) as a 2 h infusion followed by bolus 5-FU 400 mg m(-2) and a 22 h infusion of 5-FU 600 mg m(-2), repeated for 2 consecutive days every 2 weeks. All patients were assessable for toxicity and response to treatment. Four (7%) complete responses and 19 partial responses were observed (overall response rate, 38%). Stable disease was observed in 22 (36%) patients, with progressive disease in the other six (10%) patients. Median time to progression (TTP) and median overall survival (OS) were 7.1 and 11.2 months, respectively. National Cancer Institute Common Toxicity Criteria grade 3 and 4 haematologic toxicities were neutropenia, anaemia and thrombocytopenia in 36, 10 and 5% of the patients, respectively. Grade 3 peripheral neuropathy was recorded in three (5%) patients. FOLFOX-4 is an active and well-tolerated chemotherapy. Response rate (RR), TTP and OS were comparable with those of other oxaliplatin-based regimens, suggesting a role for this combination in gastric cancer.
Aims
The capacity of Lactobacillus sakei CRL1862 to prevent the growth of pathogens and its ability to degrade sarcoplasmic and myofibrillar proteins in pork meat systems was evaluated. In addition, ...basic safety aspects of Lact. sakei CRL1862 such as production of biogenic amines and antibiotic susceptibility were addressed.
Methods and Results
The bacteriocin‐producing Lact. sakei CRL1862 showed respectively bactericide and bacteriostatic effect against Listeria monocytogenes and Staphylococcus aureus in beaker sausage assay during 9 days of storage at 22°C. The hydrolytic effect of Lact. sakei CRL1862 on protein extracts was evaluated by SDS‐PAGE and reverse phase HPLC. A more pronounced proteolysis was evidenced in inoculated sarcoplasmic proteins compared with myofibrillar extracts with the generation of predominantly hydrophilic peptides and increase of total free amino acids concentration. Lactobacillus sakei CRL1862 produced neither histamine nor tyrosine and exhibited no resistance to the antibiotics assayed.
Conclusions
Lactobacillus sakei CRL1862 effectively controlled the growth of L. monocytogenes and Staph. aureus; moreover, it was able to hydrolyse pork meat extracts generating peptides and amino acids, which may improve hygienic and sensorial attributes of fermented meat products.
Significance and Impact of the Study
The use of an integrated approach to evaluate the major traits of Lact. sakei CRL1862 showed it can be applied as an autochthonous functional starter in meat fermentation.
The inhibitory activity of lactocin 705/AL705 (2133 arbitrary units per ml (AU ml-1)), two bacteriocins produced by Lactobacillus curvatus CRL705 and nisin (1066 AU m-1) produced by Lactococcus ...lactis CRL1109 in combination with chelating agents against Escherichia coli strains in TSB medium at 21 and 6 °C was investigated. Treatment with EDTA (500 and 1000 mm) and Na lactate (800 mm) alone produced a variable effect depending on the strain, Na lactate being inhibitory against E. coli NCTC12900 at both assayed temperatures while EDTA (1000 mm) led to its inactivation only at 6 °C. Direct and deferred strategies using EDTA and Na lactate showed that the direct addition of bacteriocins and chelators was not as effective as compared to deferred treatments. When the deferred treatment effectiveness was evaluated at 6 °C, the use of EDTA (500 and 1000 mm) and Na lactate (800 mm) in combination with lactocin 705/AL705 demonstrated to be the most inhibitory strategy against both E. coli strains. Nevertheless, treatments with chelators and bacteriocins was highly dependent upon strain sensitivity. Permeabilization of the outer membrane of E. coli strains with EDTA and Na lactate combined with lactocin 705/AL705 showed to be valuable in controlling this foodborne bacteria at low temperatures.
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