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Frontiers in Microbiology 2022In order to develop strategies for preventing biofilm formation in the dairy industry, a deeper understanding of the interaction between different species during biofilm...
In order to develop strategies for preventing biofilm formation in the dairy industry, a deeper understanding of the interaction between different species during biofilm formation is necessary. Bacterial strains of the group are known as the most important biofilm-formers on the surface of dairy processing equipment that may attract and/or shelter other spoilage or pathogenic bacteria. The present study used different strains of the group as background microbiota of milk, and evaluated their interaction with , , O157:H7, and Typhimurium during dual-species biofilm formation on stainless steel surfaces. Two separate scenarios for dual-species biofilms were considered: concurrent inoculation of and pathogen (CI), and delayed inoculation of pathogen to the pre-formed biofilm (DI). The gram-positive pathogens used in this study did not form dual-species biofilms with strains unless they were simultaneously inoculated with strains. O157:H7 was able to form dual-species biofilms with all seven group strains, both in concurrent (CI) and delayed (DI) inoculation. However, the percentage of contribution varied depending on the strains and the inoculation scenario. contributed to biofilm formation with all seven group strains under the CI scenario, with varying degrees of contribution. However, under the DI scenario, Typhimurium did not contribute to the biofilm formed by three of the seven group strains. Overall, these are the first results to illustrate that the strains within the group have significant differences in the formation of mono-or dual-species biofilms with pathogenic bacteria. Furthermore, the possibility of forming dual-species biofilms with pathogens depends on whether the pathogens form the biofilm simultaneously with the group strains or whether these strains have already formed a biofilm.
PubMed: 36386714
DOI: 10.3389/fmicb.2022.1053239 -
Frontiers in Plant Science 2022Plant growth-promoting bacteria (PGPBs) could be developed as a sustainable strategy to promote plant growth and yield to feed the ever-growing global population with...
INTRODUCTION
Plant growth-promoting bacteria (PGPBs) could be developed as a sustainable strategy to promote plant growth and yield to feed the ever-growing global population with nutritious food. Foliar application of nano-zinc oxide (ZnO) is an environmentally safe strategy that alleviates zinc (Zn) malnutrition by improving biochemical attributes and storage proteins of grain.
METHODS
In this context, the current study aimed to investigate the combined effect of seed inoculation with PGPBs and foliar nano-ZnO application on the growth, biochemical attributes, nutrient metabolism, and yield of maize in the tropical savannah of Brazil. The treatments consisted of four PGPB inoculations [i.e., without inoculation () () (), which was applied on the seeds] and two doses of Zn (i.e., 0 and 3 kg ha, applied from nano-ZnO in two splits on the leaf).
RESULTS
Inoculation of with foliar ZnO application increased shoot dry matter (7.3 and 9.8%) and grain yield (17.1 and 16.7%) in 2019-20 and 2020-2021 crop seasons respectively. Inoculation with A. brasilense increased 100-grains weight by 9.5% in both crop seasons. Shoot Zn accumulation was improved by 30 and 51% with inoculation of P. fluorescens in 2019-20 and 2020-2021 crop seasons. Whereas grain Zn accumulation was improved by 49 and 50.7% with inoculation of and P. fluorescens respectively. In addition, biochemical attributes (chlorophyll a, b and total, carotenoids, total soluble sugar and amino acids) were improved with inoculation of along with foliar nano ZnO application as compared to other treatments. Co-application of P. fluorescens with foliar ZnO improved concentration of grains albumin (20 and 13%) and globulin (39 and 30%). Also, co-application of and foliar ZnO improved concentration of grains glutelin (8.8 and 8.7%) and prolamin (15 and 21%) in first and second seasons.
DISCUSSION
Therefore, inoculation of and with foliar nano-ZnO application is considered a sustainable and environmentally safe strategy for improving the biochemical, metabolic, nutritional, and productivity attributes of maize in tropical Savannah regions.
PubMed: 36714773
DOI: 10.3389/fpls.2022.1046642 -
Journal of Food Science and Technology Jan 2023and were two bacteria commonly caused the spoilage of vegetables through biofilm formation and secretion of extracellular enzymes. In this study,...
UNLABELLED
and were two bacteria commonly caused the spoilage of vegetables through biofilm formation and secretion of extracellular enzymes. In this study, N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-Octanoyl-L-homoserine lactone (C8-HSL) were confirmed as acylated homoserine lactones (AHLs) signal molecule produced by and , respectively. In addition, quorum sensing inhibitory (QSI) effects of hexanal on AHLs production were evaluated. Hexanal at 1/2 minimum inhibitory concentration (MIC) was achieved 76.27% inhibitory rate of 3-oxo-C6-HSL production in and a inhibitory rate of C8-HSL (60.78%) in . The amount of biofilm formation and activity of extracellular enzymes treated with 1/2 MIC of hexanal were restored with different concentrations (10 ng/mL, 50 ng/mL, 100 ng/mL) of exogenous AHLs ( < 0.05), which verified QSI effect of hexanal on biofilm and extracellular enzymes were due to its inhibition on AHLs production. Molecular docking analysis showed that hexanal could interact with EcbI and PcoI protein to disrupt AHLs production. Furthermore, results showed that sub-MICs of hexanal could suppress expressions of and genes in AHL-mediated QS system of and . This study provides theoretical support for the application of essential oils as QS inhibitors in the preservation of vegetables.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1007/s13197-022-05624-9.
PubMed: 36618067
DOI: 10.1007/s13197-022-05624-9 -
Journal of Vector Borne Diseases 2022Bacillus subtilis subsp. subtilis (VCRC B471) and Pseudomonas fluorescens (B426) produce mosquitocidal biosurfactant, surfactin and di-rhamnolipid. The objective of the...
BACKGROUND & OBJECTIVES
Bacillus subtilis subsp. subtilis (VCRC B471) and Pseudomonas fluorescens (B426) produce mosquitocidal biosurfactant, surfactin and di-rhamnolipid. The objective of the study was to carry out a small-scale field evaluation of the two biosurfactants to determine the efficacy, application dosage, residual activity and frequency of application against Anopheles stephensi immatures in selected sites in Goa, India.
METHODS
Surfactin (VCRC B471) and di-rhamnolipid (VCRC B426) were formulated as aqueous suspensions (5% AS), and were applied at the dosages of 34, 51 and 68 mL/m and 27, 41 and 54 mL/m respectively. Two experiments were carried out with the two formulations.
RESULTS
Surfactin (VCRC B471) formulation was effective at all the dosages and there was sustained reduction (>80%) in immature density in the treated sites up to 18 days in experiment 1 and up to 15 days in experiment 2. No pupae were found in the treated sites throughout the study. Di-rhamnolipid (VCRC B426) formulation was also found to reduce the immature density in the treated sites up to 14 days in experiment 1 and up to 15 days in experiment 2.
INTERPRETATION & CONCLUSION
For VCRC B471, the optimum application dosage determined was 51 mL/m and for VCRC B426, 27mL/m. The formulations are to be applied fortnightly for effective control of Anopheles. The application dosage determined in the present study can be used for large scale field evaluation to assess their suitability for use in public health programmes for the control of Anopheles mosquitoes vectoring malaria.
Topics: Animals; Humans; Anopheles; Pseudomonas fluorescens; Malaria; Mosquito Vectors; Bacillus subtilis
PubMed: 36511041
DOI: 10.4103/0972-9062.342401 -
Foods (Basel, Switzerland) Jan 2021In dairy processing environments, many bacterial species adhere and form biofilms on surfaces and equipment, leading to foodborne illness and food spoilage. Among them,...
In dairy processing environments, many bacterial species adhere and form biofilms on surfaces and equipment, leading to foodborne illness and food spoilage. Among them, and spp. could be present in mixed-species biofilms. This study aimed to evaluate the interactions between and in biofilms simulating dairy processing conditions, as well as the capability of in co-culture to produce the blue pigment in a Ricotta-based model system. The biofilm-forming capability of single- and mixed-cultures was evaluated on polystyrene (PS) and stainless steel (SS) surfaces at 12 °C for 168 h. The biofilm biomass was measured, the planktonic and sessile cells and the carbohydrates in biofilms were quantified. The biofilms were also observed through Confocal Laser Scanning Microscopy analysis. Results showed that only was able to form biofilms on PS. Moreover, in dual-species biofilms at the end of the incubation time (168 h at 12 °C), a lower biomass compared to mono-species was observed on PS. On SS, the biofilm cell population of was higher in the dual-species than in mono-species, particularly after 48 h. Carbohydrates quantity in the dual-species system was higher than in mono-species and was revealed also at 168 h. The production of blue pigment by was revealed both in single- and co-culture after 72 h of incubation (12 °C). This work highlights the interactions between the two species, under the experimental conditions studied in the present research, which can influence biofilm formation (biomass and sessile cells) but not the capability of to produce blue pigment.
PubMed: 33467189
DOI: 10.3390/foods10010176 -
Life (Basel, Switzerland) Mar 2021Is it possible to improve the efficiency of bioremediation technologies? The use of mixed cultures of bacteria and fungi inoculated at the rhizosphere level could...
Is it possible to improve the efficiency of bioremediation technologies? The use of mixed cultures of bacteria and fungi inoculated at the rhizosphere level could promote the growth of the associated hyperaccumulating plant species and increase the absorption of metals in polluted soils, broadening new horizons on bioremediation purposes. This work investigates interactions between Ni-tolerant plant growth-promoting bacteria and fungi (BF) isolated from the rhizosphere of a hyperaccumulating plant. The aim is to select microbial consortia with synergistic activity to be used in integrated bioremediation protocols. (), () (), and group () were tested in mixes (, , , and ). These strains were submitted to tests (agar overlay, agar plug, and distance growth co-growth tests), tailored for this aim, on Czapek yeast agar (CYA) and tryptic soy agar (TSA) media and incubated at 26 ± 1 °C for 10 days. BF growth, shape of colonies, area covered on plate, and inhibition capacity were evaluated. Most BF strains still exhibit their typical characters and the colonies separately persisted without inhibition (as ) or with reciprocal confinement (as and ). Even if apparently inhibited, the mix really merged, thus obtaining morphological traits representing a synergic co-growth, where both strains reached together the maturation phase and developed a sort of mixed biofilm. Indeed, bacterial colonies surround the mature fungal structures adhering to them without any growth inhibition. First data from in vivo experimentation with and inocula in pot with metalliferous soils and hyperaccumulator plants showed their beneficial effect on plant growth. However, there is a lack of information regarding the effective co-growth between bacteria and fungi. Indeed, several studies, which directly apply the co-inoculum, do not consider suitable microorganisms consortia. Synergic rhizosphere BFs open new scenarios for plant growth promotion and soil bioremediation.
PubMed: 33806067
DOI: 10.3390/life11040273 -
Life (Basel, Switzerland) Dec 2021Use of antibiotics for the treatment and prevention of bacterial infections in humans, agri- and aquaculture as well as livestock rearing leads to antibiotic pollution...
Use of antibiotics for the treatment and prevention of bacterial infections in humans, agri- and aquaculture as well as livestock rearing leads to antibiotic pollution of fresh water and these antibiotics have an impact on free-living bacteria. While we know which antibiotics are most common in natural environments such as rivers and streams, there is considerable uncertainty regarding antibiotics' interactions with one another and the effect of abiotic factors such as temperature. Here, we used an experimental approach to explore the effects of antibiotic identity, concentration, mixing and water temperature on the growth of , a common, ubiquitous bacterium. We exposed to the four antibiotics most commonly found in surface waters (ciprofloxacin, ofloxacin, sulfamethoxazole and sulfapyridine) and investigated antibiotic interactions for single and mixed treatments at different, field-realistic temperatures. We observed an overall dependence of antibiotic potency on temperature, as temperature increased efficacy of ciprofloxacin and ofloxacin with their EC lowered by >75% with a 10 °C temperature increase. Further, we show that mixtures of ciprofloxacin and ofloxacin, despite both belonging to the fluoroquinolone class, exhibit low-temperature-dependent synergistic effects in inhibiting bacterial growth. These findings highlight the context dependency of antibiotic efficacy. They further suggest antibiotic-specific off-target effects that only affect the bacteria once they enter a certain temperature range. This has important implications as freshwater systems already contain multi-drug antibiotic cocktails and are changing temperature due to environmental warming. These factors will interact and affect aquatic food webs, and hence this creates an urgent need to adapt and improve laboratory testing conditions to closer reflect natural environments.
PubMed: 34947966
DOI: 10.3390/life11121435 -
Italian Journal of Food Safety Mar 2023Biofilms represent an evolutionary form of life, which translates from life in free-living cells to a community lifestyle. In natural habitats, biofilms are a...
Biofilms represent an evolutionary form of life, which translates from life in free-living cells to a community lifestyle. In natural habitats, biofilms are a multispecies complex, where synergies or antagonisms can be established. For example, and are associated with a dual-species biofilm that is widespread in dairy plants. In food plants, multiple strategies are devised to control biofilms, including natural compounds such as essential oils (EOs). In this respect, this study evaluated the effectiveness of (L.) Cav. (TEO) and (CEO) against a dual-species biofilm of and , mimicking dairy process conditions. Based on Minimum Inhibitory Concentrations results, the EOs concentration (10 μL/mL) was chosen for the antibiofilm assay at 12°C on polystyrene (PS), and stainless-steel surfaces for 168 h, using a Ricotta-based model system as culture medium. Biofilm biomass was assessed by crystal violet staining, and the planktonic and sessile cells were quantified in terms of Log CFU/cm. Results showed that CEO displayed the greatest antibiofilm activity, reducing significantly (P<0.05) and sessile cells of about 2.5 and 2.8 Log CFU/cm after 72 h, respectively. However, gained the protection of , evading CEO treatment and showing a minimal sessile cell reduction of 0.7 Log CFU/cm after 72 h. Considering the outcome of this study, CEO might have promising perspectives for applications in dairy facilities.
PubMed: 37064519
DOI: 10.4081/ijfs.2023.11048 -
BMC Microbiology Apr 2021Faba bean (Vicia faba L.) cultivation is highly challenged by faba bean black root rot disease (Fusarium solani) in high lands of Ethiopia. To ensure sustainable...
In-vitro compatibility assay of indigenous Trichoderma and Pseudomonas species and their antagonistic activities against black root rot disease (Fusarium solani) of faba bean (Vicia faba L.).
BACKGROUND
Faba bean (Vicia faba L.) cultivation is highly challenged by faba bean black root rot disease (Fusarium solani) in high lands of Ethiopia. To ensure sustainable production of faba beans, searching for eco-friendly disease management options is necessary to curb the progress of the disease timely. The indigenous biocontrol agents that suit local environments may effectively strive with in-situ microorganisms and suppress local pathogen strains. This study aimed to screen antagonistic indigenous compatible Trichoderma and Pseudomonas strains against Fusarium solani. In the pathogenicity test, soil-filled pots were arranged in complete random block design and sown with health faba bean seeds. The effect of some fungicides was evaluated against Fusarium by food poisoning methods to compare with the biocontrol agents. The antagonistic efficacy of biocontrol agents and their compatibility was investigated on Potato dextrose agar medium.
RESULTS
Fusarium solani AAUF51 strain caused an intense root rotting in faba bean plant. The effect of Mancozeb 80% WP at 300 ppm was comparable with Trichoderma and Pseudomonas strains against Fusarium. The mycelial growth of test the pathogen was significantly (P ≤ 0.05) reduced to 86.67 and 85.19% by Trichoderma harzianum AAUW1 and Trichoderma viridae AAUC22 strains in dual culture, respectively. The volatile metabolites of Pseudomonas aeruginosa AAUS31 (77.78%) found the most efficient in reducing mycelial growth of Fusarium followed by Pseudomonas fluorescens AAUPF62 (71.11%) strains. The cell-free culture filtrates of Pseudomonas fluorescens AAUPF62 and Pseudomonas aeruginosa AAUS31 were more efficient than the Trichoderma strain in reducing the growth of Fusarium isolates. There was no zone of inhibition recorded between Trichoderma harzianum AAUW1, Trichoderma viridae AAUC22, Pseudomonas aeruginosa AAUS31, and Pseudomonas fluorescens AAUPF62 strains, hence they were mutually compatible.
CONCLUSIONS
The compatible Trichoderma and Pseudomonas strains showed antagonistic potentiality that could be explored for faba bean protection against black root rot disease and might have a future dual application as biocontrol agents.
Topics: Microbial Interactions; Pest Control, Biological; Plant Diseases; Plant Roots; Pseudomonas; Soil Microbiology; Trichoderma; Vicia faba
PubMed: 33865331
DOI: 10.1186/s12866-021-02181-7 -
Frontiers in Microbiology 2020The aim of this study was to obtain the growth parameters of specific spoilage micro-organisms previously isolated in minced pork (MP) samples and to develop a...
The aim of this study was to obtain the growth parameters of specific spoilage micro-organisms previously isolated in minced pork (MP) samples and to develop a three-spoilage species interaction model under different storage conditions. Naturally contaminated samples were used to validate this approach by considering the effect of the food microbiota. Three groups of bacteria were inoculated on irradiated samples, in mono- and in co-culture experiments ( = 1152): , , and spp. ( and ). Samples were stored in two food packaging [food wrap and modified atmosphere packaging (CO 30%/O 70%)] at three isothermal conditions (4, 8, and 12°C). Analysis was carried out by using both 16S rRNA gene amplicon sequencing and classical microbiology in order to estimate bacterial counts during the storage period. Growth parameters were obtained by fitting primary (Baranyi) and secondary (square root) models. The food packaging shows the highest impact on bacterial growth rates, which in turn have the strongest influence on the shelf life of food products. Based on these results, a three-spoilage species interaction model was developed by using the modified Jameson-effect model and the Lotka Volterra (prey-predator) model. The modified Jameson-effect model showed slightly better performances, with 40-86% out of the observed counts falling into the Acceptable Simulation Zone (ASZ). It only concerns 14-48% for the prey-predator approach. These results can be explained by the fact that the dynamics of experimental and validation datasets seems to follow a Jameson behavior. On the other hand, the Lotka Volterra model is based on complex interaction factors, which are included in highly variable intervals. More datasets are probably needed to obtained reliable factors, and so better model fittings, especially for three- or more-spoilage species interaction models. Further studies are also needed to better understand the interaction of spoilage bacteria between them and in the presence of natural microbiota.
PubMed: 32328055
DOI: 10.3389/fmicb.2020.00639