Antibacterial Products Research Articles

Alternative therapies in controlling oral malodour: a systematic review

Is there a role for alternative therapies in controlling intra-oral halitosis? Treatments other than tongue cleaning and anti-halitosis products containing zinc, chlorhexidine and cetylpyridinium chloride were considered as alternative therapies. Four databases were searched (PubMed, EMBASE, Web of Science and The Cochrane Library). Inclusion criteria were: examination of alternative halitosis therapies, study population with oral malodour, a (negative or positive) control group and evaluation of breath odour via organoleptic and/or instrumental assessment. Data were extracted for descriptive analysis. The screening of 7656 titles led to the inclusion of 26 articles. Analysis showed heterogeneity concerning the population of interest (from cysteine-induced to genuine halitosis), the examined treatment and the reported outcomes. This made a meta-analysis impossible. Essential oils, fluoride-containing products and herbal substances were the most studied. Results varied enormously and none of the active ingredients had an unambiguously positive effect on the malodour. The risk of bias was assessed as high in all articles. Given the fact that little evidence was found for each of the investigated treatments, it could be concluded that there is currently insufficient evidence that alternative therapies are of added value in the treatment of halitosis. Clinical relevance Scientific rationale: Halitosis is a common problem causing social isolation. Out of embarrassment, patients search the internet, leading to many questions about alternative solutions (e.g. oil pulling, herbs). This is the first systematic review on these alternative therapies. Principal findings: Results varied among studies. Some promising results were found for fluoride-containing toothpastes and probiotics. For other products (such as herbal and antibacterial products and essential oils) results were inconsistent. Long-term follow-up studies on these products are scarce. Moreover, the quality of the studies was poor. Practical implications: No clear evidence was found to support a certain alternative anti-halitosis therapy.

Mg2TiO4 spinel modified by nitrogen doping as a Visible-Light-Active photocatalyst for antibacterial activity

Nitrogen doped Mg2TiO4 spinel, i.e. Mg2TiO4−xNy, has been synthesized and investigated as a photocatalyst for antibacterial activity. Mg2TiO4−xNy demonstrates superior photocatalytic activity for E. coli disinfection under visible light illumination (λ ≥ 400 nm). Complete disinfection of E. coli at a bacterial cell density of 1.0 × 107 CFU mL−1 can be achieved within merely 60 min. Mg2TiO4−xNy is capable of generating superoxide radicals (O2−) under visible light illumination which are the reactive oxygen species (ROSs) for bacteria disinfection. DFT calculations have verified the importance of nitrogen dopants in improving the visible light sensitivity of Mg2TiO4−xNy. The facile synthesis, low cost, good biocompatibility and high disinfection activity of Mg2TiO4−xNy warrant promising applications in the field of water purification and antibacterial products.

Development of novel BiOBr0.75I0.25 nanostructures with remarkably High dark phase bactericidal activities

Semiconductor materials with promising photocatalytic activities are being developed for numerous applications including their use in the development of antibacterial products. However, the light may not be available everywhere, which restrict the use of semiconductor photocatalytic materials in real applications. In this area, we report a novel nanostructure of BiOBr0.75I0.25 to show enormously high bactericidal activities even at dark. We used a solution based single step method at room temperature to produce highly porous and crystalline BiOBrxI1-x (x = 0–1) nanostructures. Next, the developed materials were thoroughly characterized by different analytical techniques, such as FESEM, XRD, XPS, etc. To evaluate the bactericidal activities Escherichia coli (gram-negative bacteria) and Bacillus subtilis (gram-positive bacteria) were selected. Interestingly we found that the solid solutions exhibited high potential towards both the bacteria and among them, BiOBr0.75I0.25 showed extremely high efficiencies even at dark. Due to their semiconductor behavior, the materials have shown higher activities in the presence of any light source. The knowledge about the behavior of these unique materials revels a new area of research and would certainly help to find out the solution for ever-increasing environmental issues.

Development of a Benzalkonium Chloride Based Antibacterial Paper for Health and Food Applications

Pathogenic bacteria and other microorganisms pose a potent threat to humans by causing various infectious diseases. To control the spread of infection, different antibacterial products have been developed. However, most of them are known to be associated with health hazards, environmental pollution, complex fabrication, and/or higher cost. To address these issues, in this study, a low cost, biodegradable and human skin compatible antibacterial paper has been developed. A quaternary ammonium compound, benzalkonium chloride (BKC) has been used for paper surface treatment. The concentration of aqueous solution of BKC coated on paper was varied from 0.1 wt% to 0.2 wt%. No external binder was required for coating BKC onto paper. The efficacy of the coated paper was investigated against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739 bacterial strains. This antibacterial paper is highly effective against both strains with the concentrations of BKC being within the allowable limit for cytotoxic effects. The optimum concentration of BKC coated on paper can be considered as 0.15 wt%, as nearly 100% inhibition was achieved with it against both strains. The developed antibacterial paper is suitable for being used in the industry for disinfection and food packaging purposes, and also by the public for hand sanitization.

Preparation of 3D printed silver nanocomposites and their antibacterial properties

The 3D printed antibacterial polymer products were rapidly sintered to obtain by selective laser sintering with highly dispersed Nano-silver modified Kaolin powder and polyamide/polypropylene composite engineering material. The preparation method of polymer products not only shortens the preparation period, but also guarantees the precision and quality of the product as well as the slow-release function of the Nano-silver.

NATURAL PRODUCTS: THE LEADING INDUSTRY AS PHARMACEUTICAL DRUGS

This review is being focused on the importance and emergence of natural products in therapeutic field due to their multiple sources and their multiple biological use. The uses of natural products are as old as 40’s and 50’s century. Many natural products are being discussed in this review that focuses on different targets, like anti-bacterial natural products in which different antibacterial agents from natural sources is being discussed with brief discussion on plant Hyssopus caspidatus. Many more activities is being discussed in this review like antifungal, anti-tumor, anti-diabetic, anti-malarial in which their mechanisms and their suitable example is described in this review

THE FUNCTIONAL CHARACTER OF Auricularia auricula CRUDE POLYSACCHARIDES: ANTIOXIDANT AND ANTIBACTERIAL ACTIVITY

The food stuffs can be clasified as functional food since the foods can improve the human health. One of them are the food stuffs which have function as antioxidant and antibacterial. These activities were studied on crude polysaccharides from Auricularia auricula. The sample was subsequently isolated using hot water and 1 M NaOH to obtain water and alkali soluble of crude polysaccharides. The antioxidant activity was evaluated using β-caroten-linoleat assay. The results showed that the alkali soluble of crude polysaccharides had the highest antioxidant activity (85.82%) at 350 μg/ml. The water and alkali soluble of crude polysaccharides from A.auricula were evaluated for their antibacterial activity using disc diffusion method. The alkali soluble of crude polysaccharides was found to have the highest antibacterial activity at 100 mg/ml against Staphylococcus aureus InaCC B4 and Escherichia coli InaCC B5 with clear zone values of 3.18 mm and 5.10 mm, respectively. The findings indicated that the alkali soluble of crude polysaccharides from A. auricula could potentially be used in part of well-balanced diets and could be considered as a potential source of natural antioxidant and antibacterial products.

Mini-Review: Antibacterial Products from Teak Leaf Extract (Tectona grandis L.)

Teak (Tectona grandis L.) is a plant that has a high resistance to weather changes and termite attacks. The dominant use of teak in the furniture industry left behind its leaf as agricultural waste (agro-waste). Several pharmacological activities have been identified in the teak leaf part. In this review article, the authors gathered information from previous studies regarding the potential use of teak leaf antibacterial compounds to be made into various antibacterial products, namely hand sanitizers, floor disinfectants, fruit and vegetable disinfectants, and deodorant. Literature searches are carried out through search engines and online journal databases. The results of the literature review show that there are at least eight antibacterial compounds from teak leaf that have been isolated, identified, and tested for their activity, namely anthratectone, naphthotectone, juglone, gallic acid, ellagic acid, rutin, quercetin, and sitosterol. Furthermore, it is known that the solvent that can be used for teak leaf extraction by providing the best antibacterial activity is ethanol. This information is used as a recommendation for optimization of teak leaf extraction as part of the author’s suggestion in making antibacterial products. In addition, previous research related to the use of ethanol extract from the teak leaf as an antibacterial product for liquid soap was also included. The study shows that the teak leaf extract liquid soap has promising activity compared to its comparable commercial soap, thereby strengthening the author's idea to utilize teak leaf extract as a component of the active ingredient of other antibacterial products, namely hand sanitizers, floor disinfectants, fruit and vegetable disinfectants, and deodorant.

The Functional Heterogeneity of Neutrophil-Derived Extracellular Vesicles Reflects the Status of the Parent Cell.

Similar to other cell types, neutrophilic granulocytes also release extracellular vesicles (EVs), mainly medium-sized microvesicles/microparticles. According to published data, authors have reached a consensus on the physical parameters (size, density) and chemical composition (surface proteins, proteomics) of neutrophil-derived EVs. In contrast, there is large diversity and even controversy in the reported functional properties. Part of the discrepancy may be ascribed to differences in the viability of the starting cells, in eliciting factors, in separation techniques and in storage conditions. However, the most recent data from our laboratory prove that the same population of neutrophils is able to generate EVs with different functional properties, transmitting pro-inflammatory or anti-inflammatory effects on neighboring cells. Previously we have shown that Mac-1 integrin is a key factor that switches anti-inflammatory EV generation into pro-inflammatory and antibacterial EV production. This paper reviews current knowledge on the functional alterations initiated by neutrophil-derived EVs, listing their effects according to the triggering agents and target cells. We summarize the presence of neutrophil-derived EVs in pathological processes and their perspectives in diagnostics and therapy. Finally, the functional heterogeneity of differently triggered EVs indicates that neutrophils are capable of producing a broad spectrum of EVs, depending on the environmental conditions prevailing at the time of EV genesis.

Fabrication and Characterization of Novel Antibacterial Ultrafine Nylon-6 Nanofibers Impregnated by Garlic Sour

Antibacterial products have paid much more attraction all over global world. In this study, a novel and economical rout has been studied for antibacterial product, ultrafine nylon-6 (NY-6 NFS) nanofibers impregnated into garlic sour was synthesized by electrospinning method. The morphology of impregnated nanofiber mats was characterized by electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) was used to analyze the chemical interaction of Nylon-6 nanofiber mats and garlic sour. The antibacterial activities of impregnated garlic sour samples G-1, G-2 and G-3 were evaluated against Escherichia coli and Staphylococcus aureus bacteria by using disc diffusion method. It was found that the garlic sour has played a vital role for antibacterial activity. The nanofiber mats impregnated into garlic sour showed excellent antibacterial activity. It was observed that the antimicrobial effect for Escherichia coli and Staphylococcus aureus was more than 99 %. The excellent hydrophobic property which revealed water contact angle was examined with dropping method and TGA were examined excellent thermal degradation rate of NY-6 NFS and impregnated garlic sour samples. NY-6 NFS showed good mechanical strength according to ASTM D-638 standard. The obtained results indicate that the NY-6 NFS impregnated in garlic sour is a promising antibacterial product that can be utilized as antibacterial wound dressing.

Antibacterial and Antifungal Properties of Composite Polyethylene Materials Reinforced with Neem and Turmeric.

With the increased scientific interest in green technologies, many researches have been focused on the production of polymeric composites containing naturally occurring reinforcing particles. Apart from increasing mechanical properties, these additions can have a wide range of interesting effects, such as increasing the resistance to bacterial and fungal colonization. In this work, different amounts of two different natural products, namely neem and turmeric, were added to polyethylene to act as a natural antibacterial and antifungal product for food packaging applications. Microscopic and spectroscopic characterization showed that fractions of up to 5% of these products could be dispersed into low-molecular weight polyethylene, while higher amounts could not be properly dispersed and resulted in an inhomogeneous, fragile composite. In vitro testing conducted with Escherichia coli, Staphylococcus aureus, and Candida albicans showed a reduced proliferation of pathogens when compared to the polyethylene references. In particular, turmeric resulted in being more effective against E. coli when compared to neem, while they had similar performances against S. aureus. Against C. albicans, only neem was able to show a good antifungal behavior, at high concentrations. Tensile testing showed that the addition of reinforcing particles reduced the mechanical properties of polyethylene, and in the case of turmeric, it was further reduced by UV irradiation.

Multifunctional chitosan-copper-gallic acid based antibacterial nanocomposite wound dressing

Antibacterial wound dressings can effectively avoid the residual of antibacterial nanomaterials for injection in vivo, reduce their biological toxicity to normal cells and tissues, making them be widely applied in biomedical field. Herein, an approach of combining ion-crosslinking, in-situ reduction and microwave-assisted methods was employed to prepare chitosan-copper-gallic acid nanocomposites (CS-Cu-GA NCs) with dual-functional nano-enzyme characteristics (oxidase- and peroxidase-like functions). The oxidase-like activity of CS-Cu-GA NCs can facilitate the production of hydrogen peroxide (H2O2) when it contacted with physiologically relevant antioxidants (AH2) in bacteria. Subsequently, H2O2 was catalyzed to generate hydroxyl radicals (OH) under the peroxidase-like activity of CS-Cu-GA NCs. Furthermore, CS-Cu-GA NCs integrate the inherent antibacterial properties of chitosan, Cu NPs and Cu2+. Animal experiments revealed that the antibacterial dressing incorporating CS-Cu-GA NCs exhibited its effective promotion of S. aureus-infected wounds healing, as well as no damage to normal tissues. Besides, the antibacterial dressing was prepared to a band aid with excellent water swelling and antibacterial properties, which was further fixed in a medical tape to construct a portable antibacterial product that can be applied to the surface of human skin and showed excellent waterproof performance, providing a new insight for the construction of clinical antibacterial wound healing products.

Green synthesis and physical properties of Gum Arabic‐silver nanoparticles and its antibacterial efficacy against fish bacterial pathogens

This study aimed to assess the antibacterial efficacy of Gum Arabic-based silver nanoparticles against certain fish bacterial pathogens. Silver nanoparticles were green-synthesized using Gum Arabic (AgNPs-GA), which served as a stabilizing and reducing agent. The AgNPs-GA were analysed using a UV spectrophotometer set at a wavelength of 450 nm. Transmission electron micrograph analysis showed that nearly all AgNPs-GA were sphere-shaped and 10.0 nm in diameter. Dynamic light scattering (DLS) analysis showed a narrow size distribution curve, whose highest peak was at 26.2 nm. The particles were negatively charged (−17.1 ± 4.9 mV). Silver concentration measured by inductively coupled plasma optical emission spectrometry (ICP-OES) and found to be 104 µg/ml. The in vitro antibacterial activity of AgNPs-GA was tested against Aeromonas hydrophila and Pseudomonas aeruginosa. Gum Arabic-silver nanoparticles exhibited clear inhibition zones of 22 and 20 mm against A. hydrophila and P. aeruginosa, with a minimum inhibitory concentration of 1.625 µg/ml and 3.25 µg/ml for AgNPs-GA respectively. The antibiofilm activity indicated that AgNPs-GA significantly inhibit A. hydrophila and P. aeruginosa biofilm formation at AgNPs-GA concentrations of 1.625 µg/ml. There was no significant difference at a AgNPs-GA concentration of 0.8215 µg/ml between the control-positive groups and the AgNPs-GA treatment groups in both bacterial strains. In summary, green-synthesized sliver nanoparticles display efficient antibacterial properties, which suggests that they would be suitable for use in a commercialized antibacterial product for the aquaculture industry.

Anti-aging potential, anti-tyrosinase and antibacterial activities of extracts and compounds isolated from Rosa chinensis cv. ‘JinBian’

Rosa chinensis cv. ‘JinBian’, a cultivar of Rosa chinensis Jacq., is one of major raw material of rose tea and possesses sufficient plant resources in China. However, the studies on the chemical constituents and cosmetic activities of R. chinensis cv. ‘JinBian’ are almost blank. The main purpose of this study was to evaluate the anti-aging, skin-whitening, and antibacterial potentials of extracts and chemical constituents of the flower by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, elastase inhibition, anti-tyrosinase, and antibacterial assays. Bioassay results suggested both 95 % and 65 % ethanol extracts possessed significant antioxidant, elastase inhibition, and anti-tyrosinase activities. The combined active extract was studied with bioassay-guided fractionation to give a new compound, kaempferol 3-O-α-l-rhamnopyranosyl (1→6)-(2”,3”-O-digalloyl)-β-d-glucopyranoside (1) and fourteen known compounds (2–15). All compounds were firstly isolated from this species and subjected to the above mentioned bioassays. Ten compounds exhibited antioxidant activities with DPPH radical scavenging rate from 63.40 %–94.04 % under the concentration of 100 μg/mL. The antioxidant activities of 1, 2-phenylethyl 1-O-β-d-(6'-O-galloyl)-glucopyranoside (12), vomifoliol (14), and 4, 4'-dimethoxy-3'-hydroxy-7, 9': 7', 9-diepoxylignan-3-O-β-d-glucopyranoside (15) were firstly found with DPPH radical scavenging rate of 83.24 %, 91.10 %, 63.40 %, and 77.75 %, respectively. The moderate elastase inhibitory activities of 12, ethyl gallate (13), and 15 were firstly found with the inhibitory rate of 43.69 %, 43.25 %, and 35.34 % at the concentration of 100 μg/mL. Multiflorin B (3), 12, and 13 showed strong tyrosinase inhibitory activities with the inhibition rate at 43.83 %–55.80 %, comparing with the positive control, α-arbutin (22.15 %). In addition, 1 showed significant antibacterial activity against Staphylococcus aureus with the MIC50 of 8.51 ± 0.26 μg/mL. Compounds 2–4 and 12–14 showed moderate antibacterial activities against S. aureus. Compounds 6 and 13 also exhibited moderate inhibitory effects against Klebsiella pneumoniae. Above results manifested that R. chinensis cv. ‘JinBian’ possessed potential application values in the development of natural anti-aging, skin-whitening and antibacterial products.

Genetic classification of two Vibrio species isolated from Florida Gulf Coast using multi-locus sequence analysis

Prokaryotic species classification has lagged dramatically behind eukaryotic species due to the dependence on the difficult DNA-DNA hybridization technique required for species designation. This is disadvantageous for the general understanding of the diversity of microbial life and unique microorganisms, along with their metabolic abilities, like bioremediation of hazardous waste. This applies to the secondary metabolites microorganisms produce that can be beneficial for humans and other living organisms, such as antibiotics or other industrially important compounds. In an effort to isolate and identify new microbial species, environmental samples were collected from marine sediment environments as marine habitats are under-sampled compared to non-marine habitats. Two marine isolates designated MI-1 and MI-2 were isolated from marine sediment environments off the Gulf Coast of Florida and chosen for further study because of their antibacterial production and unique colony pigmentation. They were genetically analyzed through sequencing of the 16s rRNA gene, shotgun cloning, and an eight-gene multi-locus sequence analysis comparison to 66 other species of the same genus. From these, MI-1 and MI-2 can be classified as members of the Vibrio genus most closely related to Vibrio ruber and a distinct strain from V. ruber type strain VR-1.

SUCUKTAN İZOLE EDİLEN PEDIOCOCCUS SUŞLARININ BAZI TEKNOLOJİK ÖZELLİKLERİNİN BELİRLENMESİ

Bu çalışmanın amacı, sucuktan izole edilen Pediococcus acidilactici (31 adet) ve Pediococcus pentasaceus (2 adet) suşlarının starter kültür olarak kullanım potansiyellerinin belirlenmesidir. Bu amaçla Pediococcus suşlarında laktik asit üretimi, proteolitik aktivite, lipolitik aktivite, nitrat redüktaz aktivitesi ve antibakteriyel madde üretim yetenekleri araştırılmıştır. Üç farklı besiyerinde (skim milk besiyeri, glukoz içeren skim milk besiyeri ve MRS broth besiyeri) 6. saat ve 24. saat sonunda yapılan pH ölçümleri kıyaslandığında en yüksek ΔpH değeri MRS broth besiyerinde 24 saat sonunda 1.71-2.49 aralığında hesaplanmıştır. En yüksek laktik asit üretimi de yine MRS broth besiyerinde 24 saat sonunda % 0.83-1.62 aralığında bulunmuştur. Suşların hiçbiri besiyeri ortamlarında proteolitik ve lipolitik aktivite göstermemiştir. Yirmi iki Pediococcus suşu kuvvetli, 4’ü ise zayıf nitrat redüktaz aktivitesi göstermiştir. Ayrıca tüm Pediococcus suşlarının indikatör bakterileri inhibe ettiği saptanmıştır. Sonuç olarak, hızlı asit üreten, nitrat redüktaz ve antibakteriyel aktiviteye sahip olduğu belirlenen Pediococcus suşlarının fermente et ürünleri üretiminde starter kültür olarak kullanılabileceği tespit edilmiştir.

Extract from Oenothera biennis L. stalks efficiently inhibits Staphylococcus aureus activity by affecting cell permeability and respiratory metabolism

Current studies on Oenothera biennis L. have focused on seeds rather than on stalks. Thus, information on the bioactive effects of O. biennis stalks is lacking. Therefore, this study investigated the antibacterial effect of O. biennis stalk extract (OBSE) and its underlying mechanisms against Staphylococcus aureus in terms of cell permeability and respiration metabolism to effectively utilize O. biennis stalks. Results showed that OBSE inhibited S. aureus growth. The diameter of the inhibitory zone reached 13.57 mm, and the minimum inhibitory concentration was 1 mg/mL. The activity of alkaline phosphatase and the levels of electronic conductivity, nucleic acid, and protein in S. aureus suspension were remarkably decreased (p < 0.01) by OBSE treatment because of the leakage of cell contents. Furthermore, OBSE inhibited S. aureus respiration. The superposition rate of OBSE and trisodium phosphate was the lowest, and the activity of glucose-6-phosphate dehydrogenase was obviously decreased (p < 0.01) by OBSE treatment. Thus, OBSE was involved in regulating the hexose monophosphate pathway. Consequently, O. biennis stalks have a potential application in antibacterial products.

Identification and in vitro evaluation of probiotic attributes of lactic acid bacteria isolated from fermented food sources.

Consumer's vigilance towards health-promoting foods beyond only taste and nutrition has increased the recognition for probiotic products. In the present study, various parameters have been studied to define the probiotic properties of cultures isolated from different fermented products. Around 118 samples were selectively screened for antimicrobial compound (AMC) producing isolates by overlay-plate assay using Micrococcus luteus ATCC9341. Among 134 zone producing isolates, 48 cultures showing Gram-positive, catalase negative, non-spore forming and non-motile rods and cocci were selected. Subsequently, 18 strains were chosen based on non-hemolytic, absence of biogenic amine production, gelatinase and lecithinase negative trait for safer isolates. These were identified by biochemical assays and then subjected to RAPD-PCR. The selected cultures DB-1aa, DB-b2-15b, Cu2-PM7, Cu3-PM8 and IB-pM15 were identified by 16S rDNA sequencing as Enterococcus durans, Enterococcus faecium, Lactobacillus plantarum, and two Lactobacillus fermentum, respectively. Several in vitro experiments were carried out including acid and bile tolerance, survival under simulated gastrointestinal condition, adhesion assay to evaluate the probiotic potential of the isolates. In addition, the isolates were studied for competent properties such as antibacterial, antioxidant activity, and enzyme production for their functional application. The results of the study prove the efficiency of selected isolates as potential probiotic cultures and hence can be recommended for application in any functional food formulations.

Antibacterial Activity of Bacillus inaquosorum Strain T1 against pirABVp -Bearing Vibrio parahaemolyticus: Genetic and Physiological Characterization.

Acute hepatopancreatic necrosis disease (AHPND) is caused by PirAB toxin-producing Vibrio parahaemolyticus and has devastated the global shrimp aquaculture industry. One approach for preventing the growth of AHPND-producing Vibrio spp. is through the application of beneficial bacteria capable of inhibiting these pathogens. In this study, we focused on the inhibitory activity of Bacillus inaquosorum strain T1, which hinders V. parahaemolyticus growth in coculture experiments in a density-dependent manner; inhibition was also observed using cell-free supernatants from T1 stationary-phase cultures. Using mariner-based transposon mutagenesis, 17 mutants having a complete or partial loss of inhibitory activity were identified. Of those displaying a total loss of activity, 13 had insertions within a 42.6-kb DNA region comprising 15 genes whose deduced products were homologous to nonribosomal polypeptide synthetases (NRPSs), polyketide synthases (PKSs), and related activities, which were mapped as one transcriptional unit. Mutants with partial activity contained insertions in spo0A and oppA, indicating stationary-phase control. The levels of expression of NRPS and PKS lacZ transcriptional fusions were negligible during growth and were the highest during early stationary phase. Inactivation of sigH resulted in a loss of inhibitor activity, indicating a role for σH in transcription. Disruption of abrB resulted in NRPS and PKS gene overexpression during growth as well as enhanced growth inhibition. Our characterization of the expression and control of an NRPS-PKS gene cluster in B. inaquosorum T1 provides an understanding of the factors involved in inhibitor production, enabling this strain's development for use as a tool against AHPND-causing Vibrio pathogens in shrimp aquaculture.IMPORTANCE The shrimp aquaculture industry has been significantly impacted by acute hepatopancreatic necrosis disease (AHPND), resulting in significant financial losses annually. AHPND is caused by strains of the bacterial pathogen Vibrio parahaemolyticus, and treatment of AHPND involves the use of antibiotics, which leads to a rise in the number of antibiotic-resistant strains. Alternative treatments include the application of beneficial microorganisms having inhibitory activities against pathogens causing AHPND. In this study, we examined the ability of Bacillus inaquosorum strain T1 to inhibit the growth of an AHPND-causing Vibrio strain, and we show that this activity involves a gene cluster associated with antibacterial compound production. We found that gene expression is under stationary-phase control and that enhanced activity occurs upon inactivation of a global transition state regulator. Our approach for understanding the factors involved in producing B. inaquosorum strain T1 inhibitory activity will allow for the development of this strain as a tool for AHPND prevention and treatment.

Microbial contamination and efficacy of disinfection procedures of companion robots in care homes.

BackgroundParo and other robot animals can improve wellbeing for older adults and people with dementia, through reducing depression, agitation and medication use. However, nursing and care staff we contacted expressed infection control concerns. Little related research has been published. We assessed (i) how microbiologically contaminated robot animals become during use by older people within a care home and (ii) efficacy of a cleaning procedure.MethodsThis study had two stages. In stage one we assessed microbial load on eight robot animals after interaction with four care home residents, and again following cleaning by a researcher. Robot animals provided a range of shell-types, including fur, soft plastic, and solid plastic. Stage two involved a similar process with two robot animals, but a care staff member conducted cleaning. The cleaning process involved spraying with anti-bacterial product, brushing fur-type shells, followed by vigorous top-to-tail cleaning with anti-bacterial wipes on all shell types. Two samples were taken from each of eight robots in stage one and two robots in stage two (20 samples total). Samples were collected using contact plate stamping and evaluated using aerobic colony count and identification (gram stain, colony morphology, coagulase agglutination). Colony counts were measured by colony forming units per square centimetre (CFU/cm2).ResultsMost robots acquired microbial loads well above an acceptable threshold of 2.5 CFU/cm2 following use. The bacteria identified were micrococcus species, coagulase negative staphylococcus, diptheriods, aerobic spore bearers, and staphylococcus aureus, all of which carry risk for human health. For all devices the CFU/cm2 reduced to well within accepted limits following cleaning by both researcher and care staff member.ConclusionsCompanion robots will acquire significant levels of bacteria during normal use. The simple cleaning procedure detailed in this study reduced microbial load to acceptable levels in controlled experiments. Further work is needed in the field and to check the impact on the transmission of viruses.