Ozon is considered an environmentally friendly, low-cost antimicrobial treatment and an effective alternative to chemical pesticides. Ozonated water in the form of droplets and mist has been used in ...two concentrations (4 and 2 mg/L) against three biomasses (102, 104, and 106 CFU/mL) of phytopathogenic bacteria Erwinia amylovora, Pseudomonas syringae, and Agrobacterium tumefaciens and fungus Botrytis cinerea that infest a wide range of crops worldwide and pose a threat to global food production. Regardless of concentration, ozone dissolved in water showed a pronounced inhibitory effect on phytopathogenic bacteria when applied in the form of droplets. However, the effect was only detected when the bacterial load was not higher than 104 CFU/mL, indicating the necessity to treat the crops and plant materials when the bacterial load is still manageable. Unlike bacterial phytopathogens, B. cinerea was the most susceptible to treatment with aqueous ozone, regardless of the applied biomass, ozone concentration, or type of application. Total removal of high biomass of B. cinerea was achieved even with the lowest ozonated water concentration thus underlying the power of ozone in treating this particular fungal contamination.
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
.
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.
Our understanding of the interactions between minerals, organic matter, and microorganisms at so-called biogeochemical interfaces in soil is still hampered by the inherent complexity of these ...systems. Artificial soil maturation experiments can help to bridge a gap in complexity between simple abiotic sorption experiments and larger-scale field experiments. By controlling other soil-forming factors, the effect of a particular variable can be identified in a simplified system. Here, we review the findings of a series of artificial soil incubation experiments with the aim of revealing general trends and conclusions. The artificial soils were designed to determine the effect of mineral composition and charcoal presence on the development of abiotic and biotic soil properties during maturation. In particular, the development of soil aggregates, organic matter (OM) composition and turnover, sorption properties, and the establishment of microbial community composition and function were considered. The main objectives of the research were to determine (1) how surface properties and sorption of chemicals modify biogeochemical interfaces; (2) how much time is required to form aggregates from mixtures of pure minerals, OM, and a microbial inoculum; and (3) how the presence of different mineral and charcoal surfaces affects aggregation, OM turnover, and the development of microbial community composition.
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.
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.
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.
Due to a large concentration of animals living in a relatively small area, air on pig farms can be contaminated by microorganisms which can have an adverse effect on animal and human health. To ...determine the microbiological air quality on a pig farm in Slavonia, as well as the differences in the microbiological air quality at different distances from the farm, air was sampled at five locations at the farm (nursery room, finishing rooms 1 and 2, service room, gestation room) and four locations at a distance of 1.5, 5, 10 and 15 m from the farm in July 2019. At each location, temperature and relative humidity were measured and air for microbiological analysis was collected in quadruplicates (n=36) by impaction method. The total aerobic mesophilic bacteria (AMB), as well as yeast and mould counts were determined on blood agar and Sabouraud dextrose agar, respectively, and expressed as CFU/m3. The AMB counts in all five farm locations, as well as the yeast and mould counts in nursery and finishing room 1 exceeded the reference values of 1.05x103 CFU/m3 for AMB and 4.1x102 CFU/m3 for yeasts and moulds. Overall, the AMB load was significantly higher (P<0.01) in indoor when compared to the outdoor air, which was not the case with yeasts and moulds (P>0.05). In addition, the abundance of airborne AMB and yeasts and moulds decreased as the distance from the farm increased.
Zbog širokog spektra aktivnosti, prirodnog podrijetla, utvrđene povijesti sigurnog korištenja i dokazane učinkovitosti, sve se više istražuje primjena eteričnih ulja kao antimikrobnih sredstava. ...Općenito, antimikrobno djelovanje eteričnih ulja određeno je sastavom i udjelom pojedinačnih spojeva, a ovisi i o vrsti mikroorganizama čiji se rast nastoji inhibirati. Dostupna znanstvena i stručna literatura upućuje na veliki potencijal upotrebe eteričnih ulja. Pokazala su se kao učinkovit konzervans u prehrambenoj i kozmetičkoj industriji, samostalno ili u kombinaciji sa sintetičkim aditivima. Dodatkom eteričnih ulja, proizvod ostaje duže mikrobiološki ispravan te ima izraženiji antioksidacijski učinak. Eterična ulja koriste se i kao sredstva za kontrolu rasta fitopatogenih plijesni i bakterija u poljoprivrednoj proizvodnji zbog svojih sigurnih, bioaktivnih, biorazgradivih, ekoloških i ekonomskih održivih svojstava. Također je dokumentirana uporaba eteričnih ulja kao antimikrobnih sredstava u farmaciji ili za kontrolu stresa i tjeskobe u aromaterapiji. Cilj je ovog rada istaknuti mogućnosti uporabe eteričnih ulja u inhibiciji rasta patogenih mikroorganizama ili mikroorganizama koji uzrokuju kvarenje te procijeniti njihovu učinkovitost kao konzervans u kozmetičkoj ili prehrambenoj industriji te kao sredstva za suzbijanje bolesti i štetnika u poljoprivrednoj proizvodnji prije i nakon žetve. Također, u ovom će radu biti prikazane najvažnije metode dobivanja eteričnih ulja te će biti opisane ključne ili najzastupljenije sastavnice eteričnih ulja.
Due to the wide range of activities, natural origin, proven safe use andefficacy, the use of essential oils as antimicrobial agents is increasingly beingresearched. In general, the antimicrobial effect of essential oils is determined bythe composition and proportion of the individual compounds and also dependson the type of microorganisms whose growth is to be inhibited. The availablescientific and professional literature points to the great potential of usingessential oils. They have proven to be effective preservatives in the food andcosmetics industry, alone or in combination with synthetic additives. Theaddition of essential oils keeps the product microbiologically intact for longerand has a more pronounced antioxidant effect. Essential oils are also used as ameans of controlling the growth of phytopathogenic molds and bacteria inagricultural production due to their safe, bioactive, biodegradable, ecologicallyand economically sustainable properties. The use of essential oils asantimicrobial agents in pharmacy or to control stress and anxiety inaromatherapy has also been documented. The aim of this paper is to emphasizethe importance of the use of essential oils in inhibiting the growth of pathogenicand/or spoilage-causing microorganisms and to evaluate their effectiveness aspreservatives in the cosmetic or food industry and as biocontrol agents in preandpost-harvest agricultural production. This paper also presents the mainmethods used to obtain essential oils and describes the main or most commoncomponents of essential.
The interaction between minerals and organic matter (OM) is a key to the turnover of OM in soils. In particular, clay minerals, iron oxides and charcoal are considered as important constituents ...affecting the sequestration of carbon (C) and nitrogen (N). Here, we incubated pre-produced artificial soils (842 days) and a natural soil (Ap, Luvisol) with¹³C- and¹⁵N-labelled plant litter over 63 days to follow OM turnover and the formation of organo-mineral associations regarding different compositions (montmorillonite (MT), illite (IL), montmorillonite + charcoal (MT+CH), illite + ferrihydrite (IL+FH)). The microbial biomass, salt extractable organic C, the isotopic C and N composition in the bulk soil and the soil fractions (combined density and particle size fractionation) were determined. By comparison of the artificial soils with the natural soil, we were able to show that the produced soil-like systems have OM dynamics comparable to the natural soil. We found out that the decomposition of the added plant litter was affected by the type of clay mineral that formed the artificial soils, as the soil MT exhibited a slower mineralisation compared to IL, which was in line with a lower microbial biomass. Although a high specific surface area (SSA) provides a high sequestration capacity for C and N, smaller amounts were sequestered in the MT soil with a higher SSA compared to the soil IL. We suppose that a more intensive decomposition is associated with a higher microbial biomass and thus leads to higher amounts of microbial products sequestered in the clay-sized fraction. Charcoal and ferrihydrite had no additional effect in this experiment.
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