Microbial communities play an important role in cheese ripening and determine the flavor and taste of different cheese types to a large extent. However, under adverse conditions human pathogens may ...colonize cheese samples during ripening and may thus cause severe outbreaks of diarrhoea and other diseases. Therefore in the present study we investigated the bacterial community structure of three raw ewe's milk cheese types, which are produced without the application of starter cultures during ripening from two production sites based on fingerprinting in combination with next generation sequencing of 16S rRNA gene amplicons. Overall a surprisingly high diversity was found in the analyzed samples and overall up to 213 OTU97 could be assigned. 20 of the major OTUs were present in all samples and include mostly lactic acid bacteria (LAB), mainly Lactococcus, and Enterococcus species. Abundance and diversity of these genera differed to a large extent between the 3 investigated cheese types and in response to the ripening process. Also a large number of non LAB genera could be identified based on phylogenetic alignments including mainly Enterobacteriaceae and Staphylococcacae. Some species belonging to these two families could be clearly assigned to species which are known as potential human pathogens like Staphylococcus saprophyticus or Salmonella spp. However, during cheese ripening their abundance was reduced. The bacterial genera, namely Lactobacillus, Streptococcus, Leuconostoc, Bifidobacterium, Brevibacterium, Corynebacterium, Clostridium, Staphylococcus, Thermoanerobacterium, E. coli, Hafnia, Pseudomonas, Janthinobacterium, Petrotoga, Kosmotoga, Megasphaera, Macrococcus, Mannheimia, Aerococcus, Vagococcus, Weissella and Pediococcus were identified at a relative low level and only in selected samples. Overall the microbial composition of the used milk and the management of the production units determined the bacterial community composition for all cheese types to a large extend, also at the late time points of cheese ripening.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The incidence of antibiotic resistance in pathogenic bacteria has become an alarming clinical and social problem. Therefore, the demand for alternative antimicrobial compounds has increased. In this ...study, a chemical profile of honey bee (Apis mellifera L.) venom (HBV) has been determined by HPLC and FTIR-ATR spectroscopy, and tested for antibacterial activity, as well as efficiency with regard to conventional antibiotics. The investigated HBV was of high quality with melittin and total protein contents of 70.10 ± 7.01%, and 84.44 ± 3.12 g/100 g, respectively. The purity of HBV was confirmed by FTIR-ATR spectral profiling, which revealed a unique pattern of absorption bands that are characteristic of its major fractions. In addition, HBV showed a broad spectrum of activity against all three tested biomasses of potentially pathogenic Gram-positive and Gram-negative bacteria with MIC values ranging between 12.5 and 200 µg/mL, and MBC between 12.5 and 400 µg/mL. When compared to conventional antibiotics, HBV (400 µg) showed up to 27.8% efficiency of tetracycline (30 µg), 52.2% erythromycin (15 µg), 21.2% ciprofloxacin (5 µg), and 34.6% of ampicillin-sulbactam (20 µg). The overall results demonstrate the therapeutic potential of the analyzed HBV.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Bacterial communities associated with the ripening process in artisanal wild boar and deer meat sausages were investigated by molecular barcoding using the 16S rRNA gene as a marker. A core ...microbiota shared by 83.54% of the samples indicated remarkable level of Lactobacillus sakei and Lactobacillus curvatus, accounting for 20.55% in initial and 70.48% in final products as well as spoilage-associated bacteria including Stenotrophomonas, Bacillus, Pseudomonas, Carnobacterium and Brochothrix, with an average abundance 44.15% at the beginning and 13.98% at the end of the production. Of selected LAB isolates (n = 555), 43.83% were not suitable for food application due to the antibiotic resistance or the presence of the tdc gene. Most of the strains designated as safe were able to grow at 25 °C even in the presence of 3.0 and 6.0% of NaCl or pH 4.5, but exposure to the same stressors resulted in growth reduction at 12 °C. Acidification and antimicrobial activity were found in 65.62% and 37.50% of strains, respectively. Most of the strains showed lipolytic and proteolytic activity, but only 9.37% were able to degrade sarcoplasmic proteins. These results give important information for the development of new starter formulation for the production of high quality game meat sausages.
•The microbiota of spontaneously fermented game meat sausages was very complex.•644 unique OTUs were detected by high-throughput 16S rRNA Illumina sequencing.•Domination of Lactobacillus spp. and high count of meat spoilage bacteria.•Considerable variation regarding the safety and technological properties of LAB strains.•Only 17.5% of tested LAB could be considered as starter or bioprotective cultures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, prevalence, biotechnological and safety profiles of 588
isolates isolated from raw milk and Istrian cheese during different stages of ripening were analyzed. Despite the low and ...variable presence of enterococci in milk ((3.65±2.93) log CFU/mL), highly comparable enterococcal populations were established after 30 days of cheese ripening ((7.96±0.80) log CFU/g), confirming
spp. as a major part of the core microbiota of Istrian cheese. The dominant species were
(53.8%) and
(42.4%), while minor groups, consisting of
(2.84%) and
(0.95%), also occurred. A pronounced intraspecies variability was noticed based on molecular fingerprinting, with 35 strains (genotypes) detected. Most of the genotypes were farm-specific with one third being shared between the farms. This genotype variability reflected particular differences of Istrian cheese production, mainly variable salt concentration, ripening temperature and air humidity as well as microclimatic or vegetation conditions. There was considerable variation between the strains of the same species regarding wide range of biotechnologically important traits as well as their ability to survive in simulated gastrointestinal conditions. A considerable number of strains were resistant to critically important antibiotics such as tetracycline (43.56%), erythromycin (35.79%) and vancomycin (23.48%). Polymerase chain reaction-based detection did not identify any of the common genetic determinants for vancomycin and erythromycin resistance; for tetracycline
gene was detected. The presence of virulence genes including
and
was frequently recorded, especially among
strains.
Population genetic analysis of variation at five neutral microsatellite loci for Mediterranean mussels (Mytilus galloprovincialis) from 18 sites along the eastern Adriatic Sea revealed little or no ...spatial variation. In contrast, seascape genetics analysis revealed a pronounced locus‐specific gradient in allelic and genotypic frequencies across the study region. At a sixth locus, MGE7, the frequencies of two alleles, MGE7243 and MGE7249, were strongly associated, negatively and positively, respectively, with a single environmental variable – minimum salinity (minSAL). The frequency of the MGE7243/243 homozygous genotype was strongly negatively associated with minSAL, whereas the frequencies of the MGE7246/249 and the MGE7249/249 genotypes were strongly positively correlated with minSAL. Interpretation of these pronounced gradients is confounded by the fact that minSAL and another environmental variable, maximum sea surface temperature (maxSST), are highly correlated (R = −.911) and are therefore not necessarily acting independently. BLAST searches of the MGE7 locus against M. galloprovincialis whole genome shotgun sequence returned an alignment with contig mg10_S01094 (accession UYJE01010330.1) and 7 predicted M. galloprovincialis proteins VDI82194.1 ‐ VDI82200.1. Conserved domain searches revealed a similar structure to the transcriptional regulator Msx2‐interacting protein. The BLASTp search also returned significant alignments to Msx2‐interacting proteins in Mytilus coruscus, Crassostrea virginica, and Haliotis rubra. The existence of the MGE7 gradient highlights the role that environmental variation may play in retarding gene flow among wild M. galloprovincialis populations, and also how the success of collection of young mussels (spat) from one site and their transfer to another site (the farm) may be influenced by a single factor such as minSAL or maxSST on a localized scale.
We investigated the genetic variation of the economically and ecologically important species the Mediterranean mussel (Mytilus galloprovincialis) from 18 sites along the eastern Adriatic Sea, using six microsatellite loci. Population genetic analysis of variation at five neutral microsatellite loci revealed little or no spatial variation. In contrast, seascape genetic analysis revealed a pronounced association between allelic and genotypic frequencies at a sixth locus, MGE7, and the environmental variable minimum salinity, highlighting the role that environmental variation may play in retarding gene flow among wild M. galloprovincialis populations.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The quality and safety of raw milk still remains a worldwide challenge. Culture-dependent methods indicated that the continuous N2 gas-flushing of raw milk reduced the bacterial growth during cold ...storage by up to four orders of magnitude, compared to cold storage alone. This study investigated the influence of N2 gas-flushing on bacterial diversity in bovine raw-milk samples, that were either cold stored at 6°C or additionally flushed with pure N2 for up to one week. Next-generation sequencing (NGS) of the V1-V2 hypervariable regions of 16S rRNA genes, derived from amplified cDNA, which was obtained from RNA directly isolated from raw-milk samples, was performed. The reads, which were clustered into 2448 operational taxonomic units (OTUs), were phylogenetically classified. Our data revealed a drastic reduction in the diversity of OTUs in raw milk during cold storage at 6°C at 97% similarity level; but, the N2-flushing treatment alleviated this reduction and substantially limited the loss of bacterial diversity during the same cold-storage period. Compared to cold-stored milk, the initial raw-milk samples contained less Proteobacteria (mainly Pseudomonadaceae, Moraxellaceae and Enterobacteriaceae) but more Firmicutes (mainly Ruminococcaceaea, Lachnospiraceae and Oscillospiraceaea) and Bacteroidetes (mainly Bacteroidales). Significant differences between cold-stored and additionally N2-flushed milk were mainly related to higher levels of Pseudomononadaceae (including the genera Pseudomonas and Acinetobacter) in cold-stored milk samples; furthermore, rare taxa were better preserved by the N2 gas flushing compared to the cold storage alone. No major changes in bacterial composition with time were found regarding the distribution of the major 9 OTUs, that dominated the Pseudomonas genus in N2-flushed or non-flushed milk samples, other than an intriguing predominance of bacteria related to P. veronii. Overall, this study established that neither bacteria causing milk spoilage nor any well-known human pathogen or anaerobe benefited from the N2 gas flushing even though the N2-flushed and non-flushed cold-stored milk differed in bacterial counts by up to 104-fold.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Due to numerous bioactive constituents, both bee pollen (BP) and bee bread (BB) represent valuable food supplements. The transformation of BP into BB is a complex biochemical in-hive process that ...enables the preservation of the pollen’s nutritional value. The aim of this study was to determine the depth of the honeycomb cells in which bees store pollen and to provide a spectral insight into the chemical changes that occur during the BP-to-BB transformation process. This study was carried out on three experimental colonies of Apis mellifera carnica, from which fresh BP was collected using pollen traps, while BB samples were manually extracted from the cells two weeks after BP sampling. The samples were analyzed using infrared (FTIR-ATR) spectroscopy, and the depth of the cells was measured using a caliper. The results showed that the average depth of the cells was 11.0 mm, and that the bees stored BB up to an average of 7.85 mm, thus covering between ⅔ and ¾ (71.4%) of the cell. The FTIR-ATR analysis revealed unique spectral profiles of both BP and BB, indicating compositional changes primarily reflected in a higher water content and an altered composition of the carbohydrate fraction (and, to a lesser extent, the lipid fraction) in BB compared to BP.
This study investigated the effect of stocking density on growth performance, blood biochemical profiles, antioxidative capacity, and muscle quality of gibel carp (
Carassius gibelio
)
.
Gibel carps ...(initial body weight 57.04 ± 1.89 g) were reared at high stocking density (HSD, 10.85 kg m
−3
), medium stocking density (MSD, 5.06 kg m
−3
), and low stocking density (LSD, 1.47 kg m
−3
) for 60 days. The LSD group exhibited the highest growth rate, while HSD significantly inhibited fish growth. The muscular compositions of crude fat, crude ash, and moisture were significantly changed by stocking density, but crude protein content did not differ significantly. The stocking density altered the muscular texture profiles of gibel carp. Compared to either the HSD group or the MSD group, the highest levels of resilience and springiness occurred in the LSD group. Significant differences were observed in the levels of plasma glucose, alanine aminotransferase, aspartate aminotransferase, cholesterol, and creatinine among three groups. The fish exhibited the highest level of plasma cortisol as well as the lowest levels of triiodothyronine and thyroxine in the HSD group. The fish stocked in the LSD group showed the highest activities of superoxide dismutase, glutathione peroxidase, and catalase as well as the highest content of glutathione in liver. The significant highest total antioxidant capacity occurred in the fish stocked in the LSD group. The results showed that HSD resulted in chronic crowding stress, and exerted negative impact on growth performance, muscle quality, and antioxidative capacity of gibel carp.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Nutrient turnover in soils is strongly driven by soil properties, including clay mineral composition. One main nutrient is phosphorus (P), which is known to be easily immobilized in soil. Therefore, ...the specific surface characteristics of clay minerals might substantially influence P availability in soil and thus the microbial strategies for accessing P pools. We used a metagenomic approach to analyze the microbial potential to access P after 842 days of incubation in artificial soils with a clay mineral composition of either non-expandable illite (IL) or expandable montmorillonite (MT), which differ in their surface characteristics like soil surface area and surface charge. Our data indicate that microorganisms of the two soils developed different strategies to overcome P depletion, resulting in similar total P concentrations. Genes predicted to encode inorganic pyrophosphatase (
ppa
), exopolyphosphatase (
ppx
), and the
pstSCAB
transport system were higher in MT, suggesting effective P uptake and the use of internal poly-P stores. Genes predicted to encode enzymes involved in organic P turnover like alkaline phosphatases (
phoA
,
phoD
) and glycerophosphoryl diester phosphodiesterase were detected in both soils in comparable numbers. In addition, P
o
concentrations did not differ significantly. Most identified genes were assigned to microbial lineages generally abundant in agricultural fields, but some were assigned to lineages known to include oligotrophic specialists, such as
Bacillaceae
and
Microchaetaceae
.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
As fermentation is an integral feature of both, dry sausage and cheese production, this has led to the evaluation of bacterial cultures
ssp.
(LL8307) and
(ED0207) originally isolated from artisanal ...Croatian hard type cheese to diversify the range of flavours of dry fermented sausages and to increase their microbiological safety. Both strains were chosen for their high or medium acidifying, proteolytic and/or lipolytic activity and bioprotective potential after step-by-step selection of wild isolates. Therefore, this study aims to evaluate the survival rate of selected starter cultures in wild boar meat sausages during the ripening period of 40 days at a local small-scale facility under artisanal conditions as well as their influence on sausage quality parameters.
Safety, biotechnological and probiotic properties of twenty-three enterococcal and lactococcal isolates of dairy origin were studied. Based on the results, two best candidates were selected and added to the meat batter during the artisanal wild boar meat sausage preparation where their survival rate, effect on physicochemical, microbiological and sensorial properties and histamine content were evaluated.
As revealed by repetitive element-polymerase chain reaction (rep-PCR), native starter cultures survived up to 15 days of ripening and were either absent from (LL8307) or reduced by 80% (ED0207) in final products. The application of native starter cultures rapidly decreased pH (p<0.05), leading to the significantly lower load of
coliforms and
in ready-to-eat sausages prepared by the addition of starter cultures (3.04-3.94 log CFU/g) than in the control (3.88-5.00 log CFU/g). Analysis of hedonic test data revealed that some of the sensory traits (odour, flavour, juiciness) of treatments with starter cultures were highly liked by the higher percentage of consumers. The results suggest that these starter cultures would represent a valuable tool to improve the homogeneity of artisanal manufacture and hygienic quality of fermented sausages and can be safely used for food application.
This is the first study to explore in depth the biotechnological potential of bacterial cultures isolated from artisanal Croatian cheese as functional starter cultures for high-quality game meat sausage production.
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