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The efficiency of seven disinfectants (Divomil Forte, Nobactel, Domestos, SU 392, Buraton, Descosal, Cidex) was tested against Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 10231, Bacillus subtilis ATCC 6633, Aspergillus niger ATCC 16404. Surface test was used in order to evaluate the efficiency of disinfectants during the everyday sanitizing practice on special industrial surfaces. Test organisms represented pathogenic, spore forming bacteria, yeast and mould. Surface test was started with minimal concentration of agents and was not increased above the maximal concentrations, which were recommended by manufacturers in order not to corrode surfaces or risk the safety of use. Test organisms were inoculated on test areas and after drying inoculated surfaces were treated with disinfectants. Seven disinfectants were tested and four were effective against every test organism. (Buraton: 1%, Descosal: 1%, Cidex: 100%, SU 392: 75%.) Two disinfectants were ineffective against Aspergillus niger (Nobactel: 2%, Domestos: 2%) and 1 against Staphylococcus aureus and Aspergillus niger (Divomil Forte: 2%).
Lipopolysaccharide and b-1,3-glucan binding protein (LGBP) is a pattern recognition receptor that can recognize and bind LPS and b-1,3-glucan. LGBP has crucial roles in innate immune defense against Gram-negative bacteria and fungi. In this study, LGBP functions in Portunus trituberculatus innate immunity were analyzed. First, the mRNA expression of PtLGBP in hemocytes, hepatopancreas, and muscle toward three typical pathogen-associated molecular patterns (PAMPs) stimulations were examined using real-time PCR. Results show that the overall trend of relative expressions of the LGBP gene in three tissues is consistent, showing up-down trend. In each group, the highest expression of the LGBP gene was at 3 and 12 h post-injection. The LGBP gene is also expressed significantly higher in the hemocytes and hepatopancreas than in the muscle. The highest level of LGBP was in the lipopolysaccharides (LPS) and glucan-injected group, whereas the lowest level was in the PGN-injected group. Furthermore, bacterial agglutination assay with polyclonal antibody specifically for PtLGBP proved that the recombinant PtLGBP (designated as rPtLGBP) could exhibit obvious agglutination activity toward Gram-negative bacteria Escherichia coli, Vibrio parahaemolyticus, and V. alginolyticus; Gram-positive bacteria Bacillus subtilis; and fungi Saccharomyces cerevisiae. LGBP in Portunus trituberculatus possibly served as a multi-functional PRR. In addition, LGBP is not only involved in the immune response against Gram-negative and fungi, as manifested in other invertebrates, but also has a significant role in anti-Gram-positive bacteria infection.
In the present investigation the acetone extracts of three macroalgae, Cystoseira amentacea, Cystoseira barbata and Cystoseira compressa, were tested for antioxidant, antimicrobial and cytotoxic potential. As a result of the study, C. amentacea extract had more potent free radical scavenging activity (IC50 = 409.81 μg/mL) than C. barbata and C. compressa extracts. For reducing power, measured values of absorbance varied from 0.0352 to 0.8873. The IC50 values for superoxide anion scavenging activity for different extracts were 521.45–976.62 μg/mL. Total phenol and flavonoid contents in extracts were 39.96–81.28 μg PE/mg and 20.85–64.58 μg RE/mg respectively. Further, all three Cystoseira species exhibited a similar antimicrobial activity. The lowest MIC value (0.312 mg/mL) was shown in the extract obtained from C. compressa against Bacillus subtilis. Finally, extract of C. amentacea expressed the strongest cytotoxic activity toward tested cell lines with IC50 values ranging from 94.72 to 186.55 μg/mL. Based on these results, it can be stated that the tested macroalgae can be used as potential natural antioxidants and antimicrobial and cytotoxic agents.
Lactic acid bacteria in fermented foods help in the improvement of flavour, preservation of the nutritive values of the raw material, and inhibition of growth or killing of food spoilage and pathogenic bacteria. Beside other metabolites, the produced bacteriocin, which is a ribosomally synthesized antimicrobial peptide, is the major metabolite involved in the killing of food spoilage microorganisms and acts as a biopreservative. In search of a bacteriocin having specific inhibitory activity against food pathogenic bacteria, isolation of bacteriocin producing lactic acid bacteria from various food items was carried out. Based on maximum production of the bacteriocin, strain BS13 was characterized and was further identified as Enterococcus faecium BS13 on the basis of physicochemical properties and 16S rRNA analysis. In MRS medium this isolate presented the maximum production of bacteriocin (27 306 AU ml−1) after 18 h of incubation period. BS13 bacteriocin showed antimicrobial activity against a wide range of bacteria, including Bacillus subtilis, Staphylococcus sp., Pediococcus sp., Listeria monocytogenes and Lactobacillus sp.
A recently introduced microtiter-plate multienzyme-inhibition assay using rabbit liver esterase (RLE), Bacillus subtilis (BS2) esterase, and cutinase from Fusarium solani pizi has been successfully transferred to high-performance thin-layer chromatography. Paraoxon, malaoxon, and carbofuran as esterase inhibitors with high, medium, and low inhibitory activity, respectively, were used to optimize method performance with regard to enzyme concentration, incubation time, and time of immersion in α-naphthyl acetate-fast blue salt B substrate. For paraoxon as strongest inhibitor, limits of detection (LOD) of 1.3, 1.2, and 540 pg per band were determined using RLE, BS2, and cutinase, respectively. Respective LODs were 7.9, 7.4, and 760 ng per band for malaoxon, and 33, 54, and 1420 ng per band for carbofuran. With regard to the LODs of strong, medium, and weak inhibitors, the detectability range is favorably reduced for the low-sensitivity cutinase (0.54–1420 ng per band) whereas it was approximately 3 × 10 4 and 5 × 10 4 for RLE and BS2, respectively.
In this study, six numerical data sets are presented valid for eighteen thyme (Thymus L.) species and characterizing three biological properties of these herbs, i.e., antioxidant, antibacterial, and anticancer activity. Four data sets characterize antioxidant properties, one data set characterizes antibacterial property, and one data set characterizes anticancer activity. Antioxidant properties were measured with two free radical standards (DPPH and ABTS), two free radical scavenger standards (trolox and gallic acid), and three analytical techniques (EPR spectroscopy, ultraviolet–visible [UV–vis] spectrophotometry, and the dot blot test with bioautographic detection). Antibacterial activity was tested upon the Gram-positive Bacillus subtilis (ATCC 6633) strain, and anticancer activity was evaluated upon the human colon adenocarcinoma cells (HCT116). It was found out that the thyme extracts characterize with all three biological activities (yet with anticancer activity not very strongly pronounced) and that in quantitative terms, each activity strongly depends on the thyme species considered. An ultimate goal of this study was to investigate if any quantitatively confirmed correlation exists among these three biological activities, which might point out to a common mechanism of their action. To this effect, six sets of numerical data underwent hierarchical clustering and Principal Component Analysis. Based on the results obtained, no quantitative correlation was established among antioxidant, antibacterial, and anticancer activity of the thyme species, which seems indicative of different molecular mechanisms of these three actions.
DL-p-chlorophenylalanine (PCPA) and its derivatives were evaluated for genotoxic effects using Escherichia coli and Bacillus subtilis strains lacking various DNA-repair mechanisms in spottest and in suspension test. The mutagenic activity of studied compounds was determined by the Ames test. Reverse mutation test was performed with Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 without S9 mix. 0.02 M nitrosomethylurea (NMU) standard mutagen was used as a positive control. The results showed that the parent nonessential amino acid PCPA had no detectable genotoxic and mutagenic activities in bacteria. The methyl ester of this amino acid and its N-phenylacetyl derivative possessed weak genotoxicity. Meanwhile N-sec-butyloxycarbonyl, N-benzyloxycarbonyl, N-(p-nitrophenylacetyl) and N-(p-nitrophenoxyacetyl) derivatives of DL-p-chlorophenylalanine exhibited appreciable genotoxi- city. Among the seven tested compounds only N-benzyloxycarbonyl and N-(p-nitrophenoxyacetyl) derivatives of DL-p-chlorophenylalanine have been found to be mutagenic. Only parent PCPA possessed antimutagenic properties in respect of nitrosomethylurea. The structural modification, which strongly affects genotoxicity and mutagenicity perhaps may be due to steric hydrance of the substituents, causing interference with enzyme and DNA interactions.
Quorum sensing (QS) is the chemical communication processes between bacteria, which may be inter-genus or intra-genus. In general, several physiological functions, such as nutrient uptake, competence development, biofilm formation, sporulation, and toxin secretion, are accomplished through QS process. The QS (cell density-dependent process) circuit in Gram-positive bacteria consists mainly of two parts: an inducer molecule and a receptor protein. The binding of inducer molecule to receptor activates the target gene, which then performs the necessary function in bacteria. In the past few years, several investigations have been conducted to explore the QS circuit in various bacteria, but still this information is insufficient to fully understand the bacterial gene expression cascade. In the present review, we summarize the QS architecture and their associated gene regulation in four Gram-positive bacteria, such as Bacillus subtilis, Staphylococcus aureus, Bacillus cereus, and Streptococcus pneumoniae. It is well established that S. aureus, B. cereus, and S. pneumoniae are potent human pathogen. A detailed understanding of QS circuit in these bacteria would be useful in preparation of customized medicine in future. Whereas, B. subtilis is an industrially important candidate and has been used in several biotechnology sectors. Understanding of QS circuit in B. subtilis will definitely enrich the antibiotics and enzyme industries.
The incidence of outbreaks of foodborne listeriosis has indicated the need for a reliable and rapid detection of the microbe in different foodstuffs. A method combining redox potential measurement and real-time polymerase chain reaction (PCR) was developed to detect Listeria monocytogenes in artificially contaminated raw milk and soft cheese. Food samples of 25 g or 25 ml were homogenised in 225 ml of Listeria Enrichment Broth (LEB) with Oxford supplement, and the redox potential measurement technique was applied. For Listeria species the measuring time was maximum 34 h. The absence of L. monocytogenes could reliably be proven by the redox potential measurement method, but Listeria innocua and Bacillus subtilis could not be differentiated from L. monocytogenes on the basis of the redox curves. The presence of L. monocytogenes had to be confirmed by real-time PCR. The combination of these two methods proved to detect < 10 cfu/g of L. monocytogenes in a cost- and time-effective manner. This method can potentially be used as an alternative to the standard nutrient method for the rapid detection of L. monocytogenes in food.
Fusarium wilt of tomato is one of the most prevalent and economically important diseases of tomato worldwide especially in tropical regions. The aims of the present study were to isolate and characterize Bacillus bacteria from tomato rhizospheric soil of various regions in Iran and determine the isolates that exhibit high levels of antagonistic efficiency against tomato Fusarium wilt pathogen, Fusarium oxysporum f. sp. lycopersici (Fol) and growth promotion activity. In this study, 303 Bacillus isolates were obtained from tomato rhizospheric soil. Dual culture and volatile metabolite tests were used to screen for antagonism of Bacillus isolates against Fol. Among them, 20 isolates were found to inhibit pathogen growth by 67.77% and 33.33% in dual culture and volatile metabolite tests, respectively. Based on the results of physiological tests and 16S rRNA and gyrA gene sequence analysis of 20 effective isolates, 11, seven and two isolates were identified as B. subtilis, B. velezensis and B. cereus, respectively. The results of greenhouse assessment showed that KR1-2, KR2-7 and A2-9 isolates which were characterized as Bacillus subtilis, reduced the disease index to 16.67% and promoted the plant growth by 80%. These isolates may serve as potential promising biocontrol agents against Fusarium wilt of tomato.
