Reduction In Bacterial Population Research Articles

Evaluation of temocillin efficacy against KPC-2-producing Klebsiella pneumoniae isolates in a hollow-fibre infection model.

Temocillin is an old antimicrobial that is resistant to hydrolysis by ESBLs but has variable activity against carbapenemase-producing Enterobacteriaceae. The current EUCAST susceptibility breakpoints for Enterobacterales are set at ≤16 mg/L (susceptible with increased exposure) based on a dose of 2 g q8h, but there is limited information on the efficacy of this dose against temocillin-susceptible carbapenemase-producing Klebsiella pneumoniae isolates. To evaluate the efficacy of this dose using a hollow-fibre infection model (HFIM) against six KPC-2-producing clinical isolates of K. pneumoniae. The isolates were characterized by WGS and temocillin susceptibility was determined using standard and high inoculum temocillin. Mutant frequencies were estimated and temocillin activity was tested in time-kill assays and in the HFIM. At standard conditions, three of the isolates were classified as susceptible (MIC ≤ 16 mg/L) and three as resistant (MIC > 16 mg/L). The HFIM was performed over 3 days to mimic human-like pharmacokinetics of 2 g q8h. Bacterial counts were performed by plating on Mueller-Hinton agar (MHA) and MHA containing 64 mg/L temocillin to detect resistant subpopulations. All isolates showed a reduction in bacterial population of at least 3 log cfu/mL within the first 8 h of simulated treatment in the hollow-fibre assay. Regrowth was observed for the three resistant isolates and one of the susceptible ones. The MIC value for these isolates was higher by at least two dilutions compared with their initial values. These data suggest that an optimized pharmacokinetic regimen may be of clinical interest for the treatment of KPC-2-producing K. pneumoniae susceptible to temocillin. These data showed activity of temocillin against KPC-2-producing K. pneumoniae susceptible to temocillin; however, a dose of 2g q8h administered over 30 min may be inadequate to prevent the emergence of resistant variants.

Durable Surface Modification of Low-Density Polyethylene/Nano-Silica Composite Films with Bacterial Antifouling and Liquid-Repelling Properties for Food Hygiene and Safety.

The growing prevalence of antimicrobial resistance in bacterial strains has increased the demand for preventing biological deterioration on the surfaces of films used in applications involving food contact materials (FCMs). Herein, we prepared superhydrophobic film surfaces using a casting process that involved the combination of low-density polyethylene (LDPE) with solutions containing surface energy-reducing silica (SRS). The bacterial antifouling properties of the modified film surfaces were evaluated using Escherichia coli O157:H7 and Staphylococcus epidermidis via the dip-inoculation technique. The reduction in bacterial populations on the LDPE film embedded with SRS was confirmed to be more than 2 log-units, which equates to over 99%, when compared to the bare LDPE film. Additionally, the modified film demonstrated liquid-repelling properties against food-related contaminants, such as blood, beverages, and sauces. Moreover, the modified film demonstrated enhanced durability and robustness compared to one of the prevalent industry methods, dip-coating. We anticipate that the developed LDPE/nano-silica composite film represents a promising advancement in the multidisciplinary aspects of food hygiene and safety within the food industry, particularly concerning FCMs.

Bacteria reduction and quality improvement of 3D printed fresh carrots by inner design and moderate microwave treatment

AbstractBacteria reduction and quality change of 3D printed carrots with different infill percentages (%) were studied after being treated with microwave (MW) at three power levels (120, 230, and 390 W). The color, appearance, texture (hardness, chewiness, and gumminess), and total polyphenol contents (TPCs) were comprehensively evaluated. The results showed that infill levels had no effect on bacterial population reduction but significantly affected the appearance of the samples after MW treatment. The total number of colonies (TNCs) were decreased by 0.27–0.68 (120 W, 60 s), 2.24–2.48 (230 W, 60 s), and 4.27–4.54 (390 W, 60 s) log CFU/g under the three MW treatments, respectively. 390 W MW treated achieved a very significant effect on inoculated Escherichia coli, with a death rate of 81.13%. MW treatment enhanced the hardness, chewiness, and TPC of the printed carrots as well as improved sticky mouthfeel without adversely affecting the visual color. The bacterial reduction effect of MW 390 W treatment for 60 s was relatively better. 60% infill sample was the best for the purpose of avoiding surface shrinkage and deformation of low infill samples and surface puffing of high infill samples.Practical applicationsIn this study, fresh vegetables were used for printing and MW sterilization was combined into 3D printing, so as to ensure the microbial safety of 3D printed products and provide technical basis for the sterilization treatment of meat, seafood, and other printed foods susceptible to microbial contamination.

Selüloz ve PLA Biyopolimer Nonwoven Malçların Toprak Sağlığına Etkisi

The nonwoven mulches produced from regenerated viscose and PLA fibres as well as conventional agro foil were placed on the soil by randomly arranged blocks of four replication plots. After 50 days, the soil samples beneath each mulch and on the control field were collected, where the bacteria and fungi population as well as the physio-chemical properties of the soil were measured. The severe reduction in bacterial population in soil under the agro foil and mulches made of PLA fibres occurs due to the prevalence of high soil temperature. The bacterial population of soil beneath the mulches made of viscose fibre significantly increased due to favourable anaerobic conditions, respectively soil temperature and moisture. Under all mulches, compared to the control field, a higher fungal population was observed. The fungal population under the nonwoven mulch produced by viscose fibres was 161% higher in comparison to the control field. The available nutrient contents of soils under the nonwoven mulches were higher compared to the control field. The control field showed higher available nutrient contents of soil than the field covered by conventional agro foil.
 The results of the study reveal that usage of nonwoven mulches made of viscose fibres is most appropriate for short-term mulching application since successfully increases microbial population and improves the physio-chemical properties of soil.

Copper-bearing titanium alloy prepared by two-wire electron beam additive manufacturing with enhanced antibacterial activity

Bacterial biofilms on titanium implant surfaces may lead to the development of peri-implant diseases. For the first time, Ti6Al4V/Cu prepared by double-wire electron beam additive manufacturing (EBAM) were subjected to in-vitro antimicrobial test. The antimicrobial activity of the materials was investigated against S.aureus and C.albicans strains depending upon the amount of copper added. Increasing the copper content in material to 9.7 wt% allowed achieving 99% bacterial population reduction on the copper-containing substrate. Such an enhanced antimicrobial acivity of the substrate was caused by the release of copper ions from the Ti6Al4/Cu alloys.

Mentha longifolia Essential Oil and Pulegone in Edible Coatings of Alginate and Chitosan: Effects on Pathogenic Bacteria in Lactic Cheese.

Mentha longifolia is a valuable medicinal and aromatic plant that belongs to Lamiaceae family. This study looked at the antibacterial effects of M. longifolia essential oil and pulegone in edible coatings made of chitosan and alginate on the growth of Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli in cheese. For this purpose, first fresh mint plant was collected from the cold region of Jiroft in Kerman province. Plant samples were dried in the shade at ambient temperature, and essential oil was prepared using Clevenger. The essential oil was analyzed by gas chromatography using mass spectrometric (GC/MS) detection. The major composition of M. longifolia oil was pulegone (26.07%), piperitone oxide (19.72%), and piperitone (11.88%). The results showed that adding M. longifolia essential oils and pulegone to edible coatings significantly reduced the growth of bacteria during storage. The bacterial population decreased by increasing the concentration of chitosan, M. longifolia, and pulegone in edible coatings. When the effects of pulegone and M. longifolia essential oils on bacteria were compared, it was found that pulegone had a stronger effect on bacterial population reduction. Coating treatments showed more antibacterial activity on E. coli than other bacteria. In general, the results of this research showed that alginate and chitosan coatings along with M. longifolia essential oil and its active ingredient pulegone had antibacterial effects against S. aureus, L. monocytogenes, and E. coli in cheese.

Egg-yolk antibodies raised to VacJ passively immunize mice against Acinetobacter baumannii pneumonia in a neutropenic murine model

There is no effective antibiotic against emerging highly resistant Acinetobacter baumannii strains, and there is a need for alternative treatment options. Egg-yolk antibodies (IgYs) are the avian equivalent of mammalian IgG that could confer passive protection against various infections. VacJ is a virulence factor of the pathogen in the lungs. In addition, previous studies have shown that immunization of mice with this antigen resulted in decreased bacterial burden in the lung. Hence, it could be a suitable antigen to achieve protective IgYs. In the current study, the recombinant VacJ was expressed, purified, and administered to laying White Leghorn hens followed by IgY extraction from egg yolks. Indirect ELISA showed maximum IgY titers against VacJ raised two weeks following the last immunization. The immunoprotective effects of IgYs were investigated in neutropenic mice. The mice received intranasal IgYs one hour before the nasal instillation of the 10 ×LD50 with a clinical isolate of A. baumannii. A significant reduction in bacterial population loaded in the lungs and spleen was noted. A 100% survival was recorded in the group receiving anti-VacJ antibodies. The results indicate that VacJ is a good immunogen for the production of anti-A. baumannii IgY.

Design of silicone interfaces with antibacterial properties

Silicone implants are widely used for plastic or reconstruction medical applications. However, they can cause severe infections of inner tissues due to bacterial adhesion and biofilm growth on implant surfaces. The development of new antibacterial nanostructured surfaces can be considered as the most promising strategy to deal with this problem. In this article, we studied the influence of nanostructuring parameters on the antibacterial properties of silicone surfaces. Nanostructured silicone substrates with nanopillars of various dimensions were fabricated using a simple soft lithography technique. Upon testing of the obtained substrates, we identified the optimal parameters of silicone nanostructures to achieve the most pronounced antibacterial effect against the bacterial culture of Escherichia coli. It was demonstrated that up to 90% reduction in bacterial population compared to flat silicone substrates can be achieved. We also discussed possible underlying mechanisms behind the observed antibacterial effect, the understanding of which is essential for further progress in this field.

Phosphatidylinositol-phospholipase C3 negatively regulates the hypersensitive response via complex signaling with MAP kinase, phytohormones and reactive oxygen in Nicotiana benthamiana.

Phospholipid signaling plays important roles in plant immune responses. Here, we focused on two phospholipase C3 (PLC3) orthologs in the Nicotiana benthamiana genome, NbPLC3-1 and NbPLC3-2. We created NbPLC3-1 and NbPLC3-2-double-silenced plants (NbPLC3s-silenced plants). In NbPLC3s-silenced plants challenged with Ralstonia solanacearum 8107, the induction of the hypersensitive response (HR), including HR-related cell death and bacterial population reduction, was accelerated, the expression level of Nbhin1, an HR marker gene was enhanced, the expression levels of genes involved in salicylic acid and jasmonic acid signaling drastically increased, the reactive oxygen species hyper-production, was accelerated, and NbMEK2-induced HR-related cell death were also enhanced. Accelerated HR-cell death was also observed by bacterial pathogens Pseudomonas cichorii and P. syringae and bacterial AvrA, oomycete INF1 and TMGMV-CP with L1 in NbPLC3s-silenced plants. Although HR-related cell death was accelerated, the bacterial population was not reduced in double NbPLC3s and NbCoi1 suppressed plants nor in NbPLC3s-silenced NahG plants. The HR-related cell death acceleration and bacterial population reduction resulting from NbPLC3s-silencing were compromised by the concomitant suppression of either NbPLC3s and NbrbohB or NbPLC3s and NbMEK2. Thus, NbPLC3s may negatively regulate both HR-related cell death and disease resistance through MAP kinase- and reactive oxygen species-dependent signaling. Disease resistance was also regulated by NbPLC3s through jasmonic acid- and salicylic acid-dependent pathways.

Phosphatidylinositol-phospholipase C4 suppresses the hypersensitive response of Nicotiana benthamiana.

Phospholipid signaling plays an important role in plant immune responses. Here, we isolated two phospholipase C4 (PLC4) orthologs in the Nicotiana benthamiana genome, designated as N. benthamiana PLC4-1 and PLC4-2 (NbPLC4-1 and NbPLC4-2). We created NbPLC4-1- and NbPLC4-2- silenced plants. Induction of the hypersensitive response (HR), including HR cell death and bacterial population reduction, was accelerated in both NbPLC4-1- and NbPLC4-2-silenced plants challenged with N. benthamiana-incompatible Ralstonia solanacearum 8107. The NbPLC4-1- and NbPLC4-2-silenced plants also showed enhanced expression of Nbhin1, a HR marker gene. Expressions of genes for salicylic acid (SA) and jasmonic acid (JA) signaling were drastically increased in NbPLC4-1- and NbPLC4-2-silenced plants by R. solanacearum inoculation. In addition, NbPLC4-1 and NbPLC4-2 silencing triggered reactive oxygen species (ROS) hyper-production. These results suggest that NbPLC4s are closely associated with JA, SA, and ROS signaling and act as negative regulators of the HR in N. benthamiana.

Production of Silver Nano-Inks and Surface Coatings for Anti-Microbial Food Packaging and Its Ecological Impact

Food spoilage is an ongoing global issue that contributes to rising carbon dioxide emissions and increased demand for food processing. This work developed anti-bacterial coatings utilising inkjet printing of silver nano-inks onto food-grade polymer packaging, with the potential to enhance food safety and reduce food spoilage. Silver nano-inks were synthesised via laser ablation synthesis in solution (LaSiS) and ultrasound pyrolysis (USP). The silver nanoparticles (AgNPs) produced using LaSiS and USP were characterised using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectrophotometry and dynamic light scattering (DLS) analysis. The laser ablation technique, operated under recirculation mode, produced nanoparticles with a small size distribution with an average diameter ranging from 7-30 nm. Silver nano-ink was synthesised by blending isopropanol with nanoparticles dispersed in deionised water. The silver nano-inks were printed on plasma-cleaned cyclo-olefin polymer. Irrespective of the production methods, all silver nanoparticles exhibited strong antibacterial activity against E. coli with a zone of inhibition exceeding 6 mm. Furthermore, silver nano-inks printed cyclo-olefin polymer reduced the bacterial cell population from 1235 (±45) × 106 cell/mL to 960 (±110) × 106 cell/mL. The bactericidal performance of silver-coated polymer was comparable to that of the penicillin-coated polymer, wherein a reduction in bacterial population from 1235 (±45) × 106 cell/mL to 830 (±70) × 106 cell/mL was observed. Finally, the ecotoxicity of the silver nano-ink printed cyclo-olefin polymer was tested with daphniids, a species of water flea, to simulate the release of coated packaging into a freshwater environment.

Scalable Synthesis of Self‐Disinfecting Polycationic Coatings for Hospital Relevant Surfaces

AbstractThe prevention of microbial infections is a global challenge. Efficient antimicrobial coatings that rapidly kill microorganisms upon contact can help minimize their transmission. However, their scalable synthesis is challenging. This work demonstrates the scalable synthesis and characterization of self‐disinfecting nanofilms for the postmodification of hospital‐relevant surfaces. Their antimicrobial action is based on charge interactions between a supercharged cationic surface film and the negatively charged bacteria membrane. Photoinitiated bulk polymerization of an air‐dried [2‐(methacryloyloxy)ethyl]trimethylammonium chloride film on cotton (gowns), nitrile rubber (protective gloves), and glass surfaces (tables, screens) is used for their supercharging, and studied with streaming potential measurements. A 6 nm thick coating dominated by cationic quarternary amine groups is shown by a combination of spectroscopic imaging ellipsometry and X‐ray photoelectron spectroscopy. Antimicrobial in vitro evaluation of the coated surfaces demonstrates up to ≈4 log reductions in bacterial populations in less than 5 min. Confocal laser scanning microscopy and live‐dead staining confirm the surface‐induced killing of bacteria. The coating's range of compatible materials and its rapid bactericidal activity can combat the surface transmission of bacteria and may help to contain the spread of infectious diseases. Its synthesis in environmental conditions is promising for integration into industrial processes.

Synthesis and characterization of luminescent Cu2+-doped fluorapatite nanocrystals as potential broad-spectrum antimicrobial agents.

Nanomaterials based on metal-doped fluorapatite (FAP) have attracted considerable interest as potential next-generation antimicrobial agents. In this study, Cu2+-doped FAP nanocrystals have been successfully synthesized by a neutralization method at room temperature. Their structural, optical, antimicrobial, and hemcompatible properties have been investigated. XRD, FTIR, FESEM, and N2 adsorption-desorption studies indicate the formation of single-phase FAP mesoporous nanopowders, composed of rod-like particles. TEM images confirmed the formation of nanorodes with a length of 60nm and a width of about 18nm. Rietveld analysis shows that the Cu2+ ions preferentially substitute Ca2 (6h) sites in the hexagonal fluorapatite crystal structure. Fluorescence spectroscopy accompanied by MCR-ALS method confirms substitution of Cu2+ ions in FAP crystal lattice with extracting additional d-d band transition at green color from FAP broadband self-activated luminescence in violet-blue color. Antimicrobial studies conducted on Staphylococcus aureus, Escherichia coli and Micrococcus lysodeikticus showed that FAP nanopowder with the highest Cu2+ content have strong bacteriostatic action on Staphylococcus aureus bacterial strain in mediums containing nutrition matters. In addition, this sample in comparison to pure FAP achieved a high percentage of relative reduction of bacterial population for all three species, being >90% in most cases. Fungistatic action is noticed too, throwgh the slowing down mycelium growth of fungus Aspergillus niger, Aspergillus flavus and Penicillium roqueforti and reduction of sporulation of Aspergillus niger species. Cu2+-doped FAP nanocrystals shows a synergistic antimicrobial effect with Cu2+ and F- ions. Concerning the potential biomedical applications, the hemolysis ratios of the Cu2+-doped FAP samples were below 5%. The obtained results pointed out the possible use of the synthesized nanocrystals as broad-spectrum antimicrobial agents for various biomedical and health care preparations.

Chitosan-hydroxyapatite composites made from sustainable sources: A morphology and antibacterial study

Chitosan (Cs) and hydroxyapatite (HA) 3D scaffolds/composites were prepared with a sustainable process, as HA was obtained using CaCO3 derived from cork, a natural material used as a template agent. The HA@Cs composites were prepared with HA in situ formation in a Cs solution, with a dissolution-precipitation mechanism.Different reaction times were considered, with time of 72 h leading to the best materials (sample CsHA_72). X-ray Diffraction (XRD) analysis confirmed HA formation. The analysis of Cs unit cell parameters showed that, for the unmodified Cs, the cell had larger dimensions and a higher degree of distortion than previously reported in literature; HA incorporation in the CsHA_72 composite led to a further increase in the cell dimensions.The morphology of the scaffolds was studied with Scanning Electron Microscopy (SEM) and a high level of porosity was observed; a statistical comparison was performed between the unmodified Cs and CsHA_72 to determine the pore size, structure, and distribution. This analysis, the first of this kind for this type of composites, showed smaller and more circular pores for the CsHA_72 composite (average diameter of 70 μm vs. 88 μm for unmodified Cs). The overall level of porosity, however, did not change (>77%); likewise, the Young modulus was not affected by HA incorporation (about 11 kPa).Antibacterial tests, performed on Escherichia coli and Staphylococcus aureus, showed that HA presence did not significantly reduce the antimicrobial properties; the composites were particularly effective towards S. aureus, as a >90% the bacterial population reduction was observed for an incubation time of 2 h. HA@Cs also showed excellent biocompatibility and good cell proliferation.The properties of these 3D scaffolds make them suitable for application as biomaterials.

Processing of raw donkey milk by pasteurisation and UV-C to produce freeze-dried milk powders: The effect on protein quality, digestibility and bioactive properties

Non-thermal processing of milk has been considered over the past decade as an alternative or adjunct to thermal processes. UV-C radiation in combination with turbulent flow of opaque liquids seems to be a promising non-thermal method for the reduction of bacterial populations in milk. Apart from confirming the efficacy of UV-C in destroying pathogens and spoilage bacteria, there is a need for assessment of the quality characteristics of the end-product and especially in added-value dairy products where bioactivity of constituents should be preserved during processing. Under this context, freeze-dried donkey milk powder processing by UV-C was studied and the effect on protein quality, digestibility and bioactive properties were assessed. Results show that UV-C treatment retains the protein's quality characteristics highly comparable to the not-treated milk (i.e. raw) rather than the pasteurized milk where some deterioration (i.e. lower bioactivities) was detected.

Effect of Commercial Probiotics on Growth Performance of Sabaki tilapia, Oreochromis spilurus

The use of beneficial bacteria to improve fish health and growth is an innovative method in aquaculture practice.  A study was conducted to test the efficiency of two commercial probiotics, such as Sanolife Pro-W and Protexin Balance on the microbial load in culture water and growth performance of Sabaki tilapia, Oreochromis spilurus in fiber glass tanks (400 liters) for a period of 75 days. Sanolife was supplied at 3ppm in the rearing water daily, and designated as Treatment 1. Protexin was incorporated at the rate of 1ppm in a supplementary feed, containing 35% protein in diet and considered as treatment 2. A control was also maintained without treating with probiotics in culture water or feed. Healthy and uniform size fish (3.1 ± 0.5g) were stocked at the rate of 25peaces/tank and both treatments and control tanks were set on a randomized design and triplicated. Water quality parameters (physical and chemical), microbial load in water, growth performance and body composition (nutrients) of fish were assessed during the culture period. Significant difference (p<0.01) on growth was observed between control and treatments, the highest growth was recorded in Protexin treated fish. Water quality parameters did not show significant variations. Carcass protein and lipid content showed significant difference between control and treatments. Considerable reduction in bacterial population and improved growth were observed in Sanolife Pro W treated water, when compared to Control. The result shows that Sanolife significantly reduce the bacterial population in culture water and Protexin improves the growth of fish. The outcome of the study has great application in the field of tilapia aquaculture sector in the Kingdom.

Survival of Clostridium perfringens, Staphylococcus aureus, Listeria monocytogenes and Salmonella enterica in alternatively cured ham during cooking and process deviations

Boneless hams were prepared with four different brines and inoculated on the surface and at a depth of 1 cm with multiple strains of Clostridium perfringens, Staphylococcus aureus, Listeria monocytogenes and Salmonella enterica. Hams were processed with a standard, low relative humidity or interrupted process cycle to an end point temperature of 70 °C. Microbiological populations were determined at the beginning, mid-point and end of the cycles. The change in population was calculated for each bacterium at each time point, by comparing the population to the initial inoculated population. There was no difference in the reductions in bacterial populations for all of the inoculated bacteria attributable to brine type. There were significant reductions in the populations of Staphylococcus aureus, Listeria monocytogenes and Salmonella enterica for both the surface and interior samples which were attributable to the end point temperature. Population reductions for Clostridium perfringens were approximately 1.8 log10 for both the surface and internal samples, and the population reductions for the surface samples were greatest with the interrupted cycle. The low Rh cycle resulted in the least reductions for the surface samples while the greatest population reductions for the surface samples were observed with the interrupted cycle.

An Injectable Antibiotic Hydrogel that Scavenges Proinflammatory Factors for the Treatment of Severe Abdominal Trauma

AbstractBacterial infection and excessive inflammation following abdominal injury can cause life‐threatening complications that lead to multiple organ failure and death. Removing bacteria and proinflammatory factors—which are predominantly negatively charged—from the wound site with a cationic, antibiotic‐containing hydrogel wound dressing is therefore a promising treatment approach for severe abdominal trauma. Here an injectable, self‐healing hydrogel composed of the gel‐forming glycosaminoglycan oxidized chondroitin sulfate (OCS), cationic polyethylenimine (PEI), and the antibiotic tobramycin (Tob) via a Schiff's base reaction is developed. Compared with hydrogels lacking either PEI or Tob, only the Tob/PEI/OCS hydrogels exhibit a large binding capacity for negatively‐charged proinflammatory factors including cell‐free DNA, lipopolysaccharides, TNF‐α, and high mobility group box 1 protein, and a large reduction in bacterial populations in vitro. In a murine model of severe abdominal trauma, the Tob/PEI/OCS hydrogel exhibits good biodegradability and biosafety, reduced local and systemic inflammation and infection, and prevents multiple organ failure, resulting in 100% survival. This hydrogel dressing is thus a promising biomaterial for preventing complications and improving outcomes following severe abdominal trauma.

Efficacy of bacteriocin-based formula for reducing staphylococci, streptococci, and total bacterial counts on teat skin of dairy cows

The use of teat dips is one of the most effective strategies to control mastitis by preventing new intramammary infections. Reducing bacterial load on teat skin helps control the spread of pathogens and spoilage and improves the quality of milk. The objective of this study was to evaluate the reduction of bacterial populations through the application of bacteriocin-based teat formulas. Teats of 12 Holstein cows received 2 different concentrations of bactofencin A, nisin, and reuterin alone or in combination, as well as iodine (positive control) and saline (negative control). Teat swabs were collected before and after application of teat formulas and analyzed for staphylococci, streptococci, and total bacteria counts. There were no differences for staphylococci, streptococci, and total bacterial counts for samples collected before application throughout the entire experiment. Reuterin-low and reuterin-high treatments reduced total bacterial count by 0.47 and 0.36 logs, respectively, whereas bactofencin A had no effect on any tested bacterial groups. Nisin-low treatment reduced staphylococci, streptococci, and total bacterial counts by 0.47, 0.30 and 0.50 logs, respectively. Nisin-high treatment resulted in 0.50, 0.50, and 0.47 log reduction for staphylococci, streptococci, and total bacterial counts. The bacteriocin consortium showed the highest reduction rates with 0.91, 0.54, and 0.90 log reductions obtained for staphylococci, streptococci, and total bacteria counts, respectively, for the low-concentration consortium. Similarly, the high-concentration consortium showed reduction rates with 0.95, 0.60, and 0.82 log reductions obtained for staphylococci, streptococci, and total bacteria counts, respectively. Thus, nisin and the bacteriocin consortium showed the most promise as a teat disinfectant by reducing staphylococci, streptococci, and total bacteria counts.

Synthesis of biogenic silver nanoparticles using butter fruit pulp extract and evaluation of their antibacterial activity against Providencia vermicola in Rohu

ObjectiveDevelopment of antimicrobial materials using nano approach and several industries like aquaculture greatly depend on novel biogenic materials. Biogenic techniques to develop nanomaterials with potent antimicrobial activity have been explored recently. The present study demonstrates the green synthesis of AgNPs using butter fruit (Persea americana) pulp extract and its antibacterial efficacy against the fish pathogen Providencia vermicola using Rohu fish. ResultsThe AgNPs were prepared and characterized using various spectroscopic and microscopic techniques. The infrared spectroscopic analysis identified that the fruit biological molecules were involved in the stabilization of AgNPs. Transmission electron microscopic analysis revealed that particles size ranged from 20 to 50 nm. Further, the nanoparticles (5 µg) encapsulated fish feed were given to P. vermicola infected Rohu fish. The survival rate observed was 72 % in experimental group as compared to the control group. Total plate count and histopathological results indicated that the AgNPs treated groups showed significant reduction of bacterial population and restore the tissues in the normal range. ConclusionThe results suggest that the green synthesized (AgNPs) using butter fruit pulp have good efficiency in reducing the infection caused by P. vermicola in Rohu fish.