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Marine species are known as rich sources of metabolites largely involved in the pharmaceutical industry. This study aimed to evaluate in silico the effect of natural compounds identified in algae on the SARS-CoV-2 Main protease, RNA-dependent-RNA polymerase activity (RdRp), endoribonuclease (NSP15) as well as on their interaction with viral spike protein. A total of 45 natural compounds were screened for their possible interaction on SARS-CoV-2 target proteins using Maestro interface for molecular docking, molecular dynamic (MD) simulation to estimate compounds binding affinities. Among the algal compounds screened in this study, three (Laminarin, Astaxanthin and 4'-chlorostypotriol triacetate) exhibited the lowest docking energy and best interaction with SARS-CoV-2 viral proteins (Main protease, RdRp, Nsp15, and spike protein). The complex of the main protease with laminarin shows the most stable RMSD during a 150 ns MD simulation time. Which indicates their possible inhibitory activity on SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Dyes are priority pollutants, commonly found at significant concentrations in textile effluents. The presence of dye stuffs in wastewater can cause severe problems to aquatic life and human beings....

Aflatoxin B1 (AFB1) is the most harmful mycotoxin. Aflatoxin occurrence in tea makes this beverage unsuitable for consumption and presented risks to human health. Therefore, researches in aflatoxin microbial degradation are necessary to overcome this problem. Kombucha beverage is associated with health promoting effects. Thus, novel strains (Lactic acid bacteria and yeasts) were isolated from a Kombucha culture and assessed for AFB1 degradation in the liquid medium (Man Rogosa and Sharpe broth, yeast extract peptone dextrose broth and black tea). The main strains involved in AFB1 decontamination were identified based on DNA sequencing and the toxicity of the new products was evaluated on Hep2 cells and on Brine shrimp (Artemia salina). Our results showed that after 7 days of fermentation, kombucha was able to degrade 97% of AFB1 in black tea. Moreover, the effective yeasts present in Kombucha were identified as Pichia occidentalis, Candida sorboxylosa and Hanseniaspora opuntiae and the highest AFB1 degradation capacity was accorded to P. occidentalis (59%) when cultivated in black tea. Data on cytotoxicity tests on Hep2 cells and Brine shrimp (Artemia salina) showed that the biodegraded products were less toxic than pure AFB1. These findings suggest that, kombucha isolated strains could be potential candidates for application in the food and feed industry with a potential aflatoxin B1 detoxification properties.

In the current study, a simple method for the synthesis of 3-methyl-2-propyl-2H-[1,2,4]triazolo[4,3b][1,2,4,6]thiatriazine-1,1-dioxide (2) was carried out. In the presence of pyridine, a reaction between amidine (1) and sulfuryl chloride occurs. FTIR spectroscopy, 1H and 13C NMR, mass spectra, and elemental analysis were utilized in order to verify the structure of a novel synthetic molecule. The antibacterial activities of compound (2) were tested against eight pathogenic bacteria and the minimum inhibitory concentration as well as minimum bactericidal concentration were determined. Moreover, the possible antibiofilm effect of compound (2) was evaluated. Molecular docking was investigated to determine the interaction between compound (2) and eight crystal structures of bacterial and yeast proteins associated with virulence activity and antimicrobial resistance. Our results showed that the new 3-methyl-2-propyl-2H-[1,2,4]triazolo[4,3b][1,2,4,6]thiatriazine-1,1-dioxide (2) compound has a moderate antibacterial activity toward the selected pathogenic bacteria. The obtained MICs varied from 32 to 512 µg/mL being the lowest values attributed to Staphylococcus epidermidis ATCC 14990 and Streptococcus mutans ATCC 25175 (MIC = 32 µg/mL).We noted also that heterocyclic compound (2) may inhibit bacterial biofilm formation at concentration depend manner with a lowest value obtained against S.mutans ATCC 25175 (BIC50= 490 µg/mL). Molecular docking showed a promising inhibitory activity of compound (2) on TetM-mediated tetracycline resistance (3J25) and Staphylococcus aureus gyrase (3G7B) with lower binding energy compared to the other target proteins. KEY WORDS: Synthesis, Thiatriazine-1,1-dioxide, Antibacterial, Antibiofilm, Molecular docking Bull. Chem. Soc. Ethiop. 2022, 36(1), 109-117. DOI: https://dx.doi.org/10.4314/bcse.v36i1.10 &nbsp

Background: Globularia alypum L. is a Mediterranean plant of the Globulariaceae family which has been used in folk medicine to cure several diseases. Different studies have been done in vitro and in vivo using diverse G. alypum extracts to understand this traditional use. Methods: In this study, Tunisian G. alypum leaf methanol extract (GAME) was chemically identified using LC-ESI-MS, then examined in vitro for its antioxidant, antibacterial, and antifungal activities. Besides, a molecular docking study was also conducted. Results: Nineteen phenolic compounds were detected, with trans-cinnamic acid (45.14%) and luteolin 7-O-glucoside (19.82%) being the dominant ones. The GAME demonstrated important antioxidant activities, especially against 2, 2-diphenyl-l-1-picrylhydrazil (DPPH) radical (IC50 = 16.1±1.1 μg.ml-1) and exhibited an anti-proliferative effect against Vero cells with (IC50 2091 ± 177 μg.ml-1). Data also reveals that the GAME inhibited the growth of oral bacteria, in particular Streptococcus oralis (MICs value ranged from 2560 to 20480 μg.ml-1). In addition, GAME has a significant antifungal action, especially against Candida albicans ATCC 90028 (MIC=2560 μg.ml-1). Docking study identified one of the major molecules (luteolin 7-O-glucoside) present in the GAME extract, displaying a good interaction with tyrosinase (docking score -9.6 kcal.mol-1) and other antibacterial (tyrosyl-tRNA synthetase, gyrase, deformylase) and antifungal (n-myristoyltransferase, chitinase) target proteins. Conclusion: This study illustrates that GAME has potent sources of antioxidants and antimicrobials useful in combating oral bacteria. Hence GAME can be of reasonable use in food technology, processing, as well as the medical field.

Fumonisin B1 (FB1) was a possible carcinogenic molecule for humans as classified by the IARC on 2B group. In livestock, it was responsible for several mycotoxicosis and economic losses. Lactobacillus strains, inhabitants of a wide range of foodstuffs as well as our gastro-intestinal tract, were Generally Recognized as Safe (GRAS). Thus, the aim of this work was to evaluate the protective effect of Lactobacillus paracasei (LP) against FB1 induced reprotoxicities including testicular histopathology, sperm quality disturbance and testosterone level reduction. Pubescent mice were divided randomly into four groups as bellow: Group1: Control; Group 2: FB1 (100 µg/kg b.w); Group 3: LP (2× 109 CFU/kg b.w); Group 4: LP (2× 109 CFU/kg b.w) and FB1 (100 µg/kg b.w) to be then treated for 10 days. After the end of the treatment, animals were sacrificed; the plasma and epididyms and testicles were harvested to the reproductive system studies. Our results highlighted that LP counteracted the harmful effect generated by FB1. Indeed; it induced sperm quality reduction, oxidative stress generation and histological alterations. In conclusion, the used strain was able to prevent FB1-reproductive system damages of in balb/c mice and could be valorised as an anti-cating agent in animal FB1-contaminated diet.

Fumonisin B1 (FB1) is a carcinogenic (Class 2B) mycotoxin produced by Fusarium fungi and is responsible for several types of mycotoxicoses in animals and humans. Lactobacillus paracasei (LP), as a probiotic, is known to impart a wide range of advantageous effects on host health. The objective of the current study was to evaluate if LP (type BEJ01) isolated from Tunisian artisanal butter, could potentially help protect a host against intestinal alterations caused by exposure to FB1. Here, adult male Balb/c mice were randomly assigned to four groups, i.e., control (vehicle only), treated with FB1 (100 µg/kg BW), LP (2 × 109 CFU/ml [≈ 2 mg/kg BW]) and FB1 (100 µg/kg BW) + LP (2 × 109 CFU/ml) and treated per os daily for 10 days. At 24 hr after the final treatment, mice were euthanized and their jejunum harvested for examination of intestinal alterations induced by the FB1. The data showed that a variety of negative effects in jejunal tissue were induced by the FB1, including DNA fragmentation, oxidative stress, apoptotic cell death, and histopathological alterations. The results also showed that co-treatment of LP with FB1 was able to mitigate the harmful FB1 effects. LP alone imparted no damage to jejunal tissues. These results show that apart from potential use as a bio-preservative for extending the shelf-life of food and feeds, LP may also provide a benefit of helping prevent untoward effects from a potent mycotoxin like FB1.

Commiphora gileadensis, locally known as becham, is a plant used in traditional Arabian medicine for treating headache, constipation, stomach, joint pain, and inflammatory disorders. Several studies have reported its antibacterial properties; however, no study has demonstrated its antiviral activity. This study aimed to evaluate the antiviral activity of C. gileadensis as well as to isolate its active compound and investigate its mode of action. This activity was evaluated using 4 viruses, herpes simplex virus type 2 (HSV-2), respiratory syncytial virus type B (RSV-B), coxsackie virus B type 3, and adenovirus type 5 by performing the plaque reduction assay and the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays for enveloped and nonenveloped viruses, respectively. The methanol extract of C. gileadensis leaves only showed antiviral activity against enveloped viruses with a selectivity index of 11.19 and 10.25 for HSV-2 and RSV-B, respectively. The study of the mechanism underlying antiviral activity demonstrated a virucidal effect by direct contact with these target viruses. The active compound, isolated using bio-guided assays involving TLC, was identified as guggulsterone by HPLC-diode array detection coupled with electrospray ionization mass spectrometry. Guggulsterone is an antagonist of the bile acid receptor and a modulator of cholesterol metabolism; however, its antimicrobial properties have been reported for the first time in this study.

The diversity of oral microbiota is affected by diets habits, gender, age, ethnic group, and environment. The acquisition of oral microbiota and the role of family on oral microbiota development is poorly understood. This study aims to characterize and compare the oral bacterial microbiota among families using 16S rRNA gene sequencing. This work was conducted in Jeddah city from 2020 to 2021, in which four families composed of 20 members of different ethnicity and lifestyle were recruited. After the collection of saliva samples, the DNA was extracted and processed for 16S rRNA gene metagenomics sequencing. Among 378 OUTs generated, 39 (10.3%) were unique in group A, 13 (3.4%) unique in group B, and 11 (2.9%) were unique in groups C and D. We observed a significant variation at the level of top abundance phylum (14), families (23), genera (24), and species (22) of bacteria among family members. Within family groups, different bacterial species were reported to be more dominant among certain family members than the other

UV-vis and impedance measurements were performed to determine the stable formation of the Hydroxychloroquine-Zinc (HCQ-Zn) complex within the oleic acid (oil) phase of the oil-water system. Decreased UV absorbance with increased Zn concentration was associated with the gradual formation of the complexes within the oil phase, agreeing with existing reports and our time-dependent-density-functional calculations. The reproducibility of our data over a long period indicates the stability of the complex within the oil phase. The impedance measurement showed that the dielectric loss of the oil phase due to the polarization of the complex is less than that due to the polarization of HCQ. A basic impedance measurement revealed that the aqueous-to-oil transfer of Zn is not possible without the HCQ, a result pertinent to the recent report that HCQ is Zn ionophore. Our work is thus important to the fundamental physical chemistry and the current COVID-19 issue where the Zn infusion across the living cell phospholipid membrane (mimicked as an oil-water interface) reduces viral replication.

Marine species are known as rich sources of metabolites involved mainly in the pharmaceutical industry. This study aimed to evaluate the effect of biologically active compounds in the marine sponge on the SARS-CoV-2 RNA-dependent-RNA polymerase protein (RdRp) using the in-silico method. A total of 51 marine compounds were checked for their possible interaction with SARS-CoV-2 RdRp using Maestro interface for molecular docking, molecular dynamic (MD) simulation, and MM/GBSA method to estimate compounds binding affinities. Among the 51 compounds screened in this study, two (mycalamide A, and nakinadine B) exhibited the lowest docking energy and best interaction. Among these compounds, mycalamide A was identified as a potent inhibitor of SARS-CoV-2 RdRp that showed the best and stable interaction during molecular dynamic simulation, with residues (Asp760 and Asp761) found in the catalytic domain of RdRp. The analysis through MM/GBSA for molecular dynamic simulation results revealed binding energy −59.7 ± 7.18 for Mycalamide A and −56 ± 10.55 for Nakinadine B. These results elucidate the possible use of mycalamide A for treating coronavirus disease. Communicated by Ramaswamy H. Sarma

The ability of Streptococcus mutans to adhere to oral surfaces and form biofilm is a key step in the tooth decay process. The aim of this study was to investigate a berry (wild blueberry, cranberry, and strawberry) polyphenolic fraction, commercialized as Orophenol®, for its antibacterial, anti-biofilm, and anti-adhesion properties on S. mutans. Moreover, the biocompatibility of the fraction with human oral epithelial cells was assessed. Phenolic acids, flavonoids (flavonols, anthocyanins, flavan-3-ols), and procyanidins made up 10.71%, 19.76%, and 5.29% of the berry polyphenolic fraction, respectively, as determined by chromatography and mass spectrometry. The berry polyphenolic preparation dose-dependently inhibited S. mutans biofilm formation while not reducing bacterial growth. At concentrations ranging from 250 to 1000 µg/mL, the fraction inhibited the adhesion of S. mutans to both saliva-coated hydroxyapatite and saliva-coated nickel–chrome alloy. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that incubating S. mutans with the berry polyphenolic fraction was associated with a reduced expression of luxS gene, which regulates quorum sensing in S. mutans. The berry fraction did not show any significant cytotoxicity in an oral epithelial cell model. In conclusion, Orophenol®, which is a mixture of polyphenols from wild blueberry, cranberry and strawberry, possesses interesting anti-caries properties while being compatible with oral epithelial cells.

The textile dyeing and printing industries has led to extensive environmental pollution and severely threatens ecosystems. The best microbial species for such application was selected among the isolated bacterial populations by conducting CI Reactive Blue 40 (CI RB 40) batch degradation studies with the bacterial-algal-probiotic strains. In this study, three suitable species (Pseudomonas putida, Chlorella and Lactobacillus plantarum) were applied to degrade and detoxify CI RB 40, a reactive diazo dye in Real Textile Wastewater, used in textile dyeing industry worldwide. Process parameters were optimized using Response Surface Methodology and under the optimum conditions (e.g., inoculum size of 10%), temperature of 35 °C, 150 ppm, and time of 6 days). The maximum COD and color removal efficiencies, when tested with 1000 ppm of dye using batch reactors were found to be 89% and 99%, respectively. Our results showed also that bacteria had a high decolorization capacity. The regression analysis revealed a good match of the experimental data to the second-order polynomial with a high coefficient of determination (R2). UV–Visible and FTIR spectroscopy analysis confirmed the biodegradation of CI RB 40. Finally, toxicity of CIRB 40 before and after biodegradation was studied and the detoxification of CIRB 40 dye solution after biodegradation process was confirmed.

Mycotoxins are secondary metabolites produced by various toxigenic fungi belonging to the genera Aspergillus, Fusarium and Penicillium. They have mutagenic, teratogenic, carcinogenic, immunosuppressive and endocrine disrupting effects on both humans and animals. The ubiquitous occurrence and heat stability of these mycotoxins during food and feed processing pose serious health problems in human and animals. Therefore successful biotechnological detoxification tools are in great demand. Recently, the use of bacteria, yeast, moulds and enzymes to mitigate/bind or biodegrade various mycotoxins is a novel strategy used for mycotoxins removal. In this review, recent development in biological control of mycotoxins removal and detoxification will be discussed.

Coronavirus disease (COVID-19) is caused by SARS-CoV-2 and represents the causative agent of a potentially lethal disease. COVID-19 has been described as a significant global public health pandemic by the World Health Organization due to its high mortality rate, rapid spread, and the lack of drugs and vaccines for it. Active antiviral drugs are desperately needed to combat the potential return of severe acute respiratory syndrome (SARS).In this study, we selected 39 natural compounds present in plants, algae, and sponges with antiviral activity. Molecular docking was used to screen the compounds’ activity on SARS- CoV-2 RNA-dependent-RNA polymerase, receptor-binding domain (RBD), and the human ACE2 receptor. Compounds with binding energy ≤ -6.5 kcal/mol enter pre-clinical testing using in silco ADME/Tox (absorption, distribution, metabolism, excretion, and toxicity).We found eight potential SARS-CoV-2 inhibitors: (glycyrrhizin, rutin, baicalin, 1, 6-di-O- galloyl-beta-D-glucose, pyropheophorbide A, pheophorbide A, beta-Sitosterol, and vitexin). These outcomes indicate that these compounds could be potential candidates to be utilized in lead optimization for the design and production of the anti-SARS-CoV-2 drug.

Dyes are chemicals found in industrial water discharge, which may harm aquatic life and humans. In this study, halophilic bacteria was isolated from sea water in Jeddah, KSA, and then identified using 16SrDNA sequencing technique. Mathematical modeling has been achieved to predict the number of runs needed to reach the maximum of dye removal. Then the effect of four independent variables (NaCl concentration, Peptone concentration, temperature and agitation) was studied using full Factorial Design (FFD) for the determination of optimal abiotic and biotic condition, which reaches a maximum percentage of colour removal (% of decolourization) in artificial seawater (ASW). A model was proposed for the statistical analysis of colour removal prediction. Analytical techniques (UV–vis and FTIR) was also used to determining the degradation mechanisms. The active strain was then genetically characterized to identify genes related to chemical and dyes biodegradation. The isolated strain was identified as Photobacterium ganghwense. Our results revealed that P. ganghwense (5.106 CFU/ mL) was able to decolourize four tested dyes (Methyl orange, Congo red, Crystal violet and Malachite green) in modified ASW with different degrees and the maximum of decolourization was attributed to malachite green (79.61%). The biodegradation capability of the selected strain was confirmed by UV–Vis spectrum and FTIR analysis. Experimental data and model predictions were found to be in good agreement. Genomic analysis confirm the presence of several enzymes (reductase, dehydrogenase, oxidase, kinase, hydrolase, and transferase) associated with dyes and xenobiotic degradation, indicating its possible use in biotechnology applications.

The mycotoxins produced by filamentous molds are associated with economic losses and numerous health risks in the human food chain. Biological methods of eliminating the danger posed by mycotoxins to the health of humans and animals are being developed. In this context, kefir (i.e., milk fermented by kefir grains), kefir cell-free supernatant (CFS), and neutralized kefir CFS (CFS-pH7) were tested for their antifungal activities against Aspergillus flavus and A. carbonarius, which produce mycotoxins. Results showed that the pH increased and the titratable acidity decreased during 24 h of fermentation. Moreover, data showed that 10% kefir has the potential to inhibit the growth of A. flavus and A. carbonarius by 93.88% and 100%, respectively. Kefir CFS inhibited the growth of A. flavus and A. carbonarius by 51.11% and 46.66%, respectively. No inhibition of the growth of A. carbonarius was observed when the pH of the CFS was adjusted to 7, while minor inhibition (10%) of the growth of A. flavus was noted. The production of OTA by A. carbonarius was completely (100%) suppressed by kefir, and it reduced the production of AFB1 by A. flavus by 99.98%. CFS and CFS-pH7 reduced AFB1 and OTA production by 99.94–92.90% and 27.98–8.76%, respectively. The present findings suggest that kefir could be utilized to control A. flavus and A. carbonarius and thus the production of AFB1 and OTA, enhancing the safety of the human food chain.

Aflatoxin B

Graphical abstract, In this study, density functional theory (DFT) and docking calculations were systematically performed to study the non-competitive interaction between Hydroxychloroquine (HCQ) and azithromycin (AZTH). The calculated changes in Gibbs free energy and enthalpy (at 310 K) were positive, indicating the non-spontaneous formation of HCQ-AZTH specifically in water media. Docking calculation confirmed the obtained DFT result as evident from the different binding sites of both drugs to the SARS-CoV-2 main protease and human angiotensin-converting enzyme 2 (ACE2) proteins. The HCQ-AZTH structure revealed enhanced electrochemical properties, suggesting the synergy between HCQ and AZTH without affecting their therapeutic efficacy against SARS-CoV-2.

The Aims of the study was to evaluate the antibacterial susceptibility and the biofilm eradication of three natural compounds carvacrol (CAR), thymol (TH) and eugenol (EUG), alone or in combination with nalidixic acid (NA) against twelve Salmonella Typhimurium strains. The minimum inhibitory concentration (MIC) and the minimum biofilm eradication concentration (BEC50) of the tested compounds (CAR, TH and EUG) and their combinations with NA were evaluated. In order to assess whether these bacteria had active efflux pumps, ethidium bromide (EtBr) accumulation assays was achieved using spectrophotometric accumulation assays. Moreover, scanning electron microscopy was used to visualize the bacterial biofilm formation on stainless steel surfaces after exposed to NA, CAR, TH and EUG alone and in combination. TH was the most effective essential oil, with the lowest MICs values ranging from 32 to 128 μg/mL followed by EUG and CAR. In addition, the combination of NA with the different compounds enhances antibiotic susceptibility of the tested bacterial strains. These results were confirmed by EtBr accumulation assays. A pronounced effect in decreasing biofilm mass was also noticed. Moreover, SEM revealed that bacterial membrane was disrupted and a complete loss of membrane integrity was also evident. The combination of natural compounds with antibiotic enhances bacterial susceptibility to NA. This combination ameliorates eradication of biofilm formed by S. Typhimurium on polystyrene microtitre plates. Additionally, this synergy induces an alteration of the bacterial cell surface visualized by SEM.

In this study thymol (THY) and carvacrol (CAR), two monoterpenic phenol produced by various aromatic plants, was tested for their antibacterial and efflux pump inhibitors potencies against a panel of clinical and foodborne pathogenes. Our results demonstrated a substantial susceptibility of the tested bacteria toward THY and CAR. Especially, THY displayed a strong inhibitory activity (MIC's values ranged from 32 to 64 μg/mL) against the majority of the tested strains compared to CAR. Moreover, a significant reduction in MIC's of TET and benzalkonium chloride (QAC) were noticed when tested in combinations with THY and CAR. Their synergic effect was more significant in the case of THY which resulted a reduction of MIC's values of TET (2–8 fold) and QAC (2–8 fold). We noted also that THY and CAR inhibited the ethidium bromide (EtBr) cell efflux in a concentration-dependent manner. The rate of EtBr accumulation in food-borne pathogen was enhanced with THY and CAR (0, 250 and 500 μg/mL). The lowest concentration causing 50% of EtBr efflux inhibition (IC 50) was noticed in Salmonella enteritidis (1129) at 150 μg/mL of THY and 190 μg/mL of CAR respectively. These findings indicate that THY and CAR may serve as potential sources of efflux pump inhibitor in food-borne pathogens.

Three bacterial strains (TE1, TD3 and FB2) were isolated from date palm (degla), pistachio and barley. The presence of nitrate reductase (narG) and nitrite reductase (nirS and nirK) genes in the selected strains was detected by PCR technique. Molecular identification based on 16S rDNA sequencing method was applied to identify positive strains. In addition, the D-optimal mixture experimental design was used to optimize the optimal formulation of probiotic bacteria for denitrification process. Strains harboring denitrification genes were identified as: TE1, Agrococcus sp LN828197; TD3, Cronobacter sakazakii LN828198 and FB2, Pedicoccus pentosaceus LN828199. PCR results revealed that all strains carried the nirS gene. However only C. sakazakii LN828198 and Agrococcus sp LN828197 harbored the nirK and the narG genes respectively. Moreover, the studied bacteria were able to form biofilm on abiotic surfaces with different degree. Process optimization showed that the most significant reduction of nitrate was 100% with 14.98% of COD consumption and 5.57 mg/l nitrite accumulation. Meanwhile, the response values were optimized and showed that the most optimal combination was 78.79% of C. sakazakii LN828198 (curve value), 21.21% of P. pentosaceus LN828199 (curve value) and absence (0%) of Agrococcus sp LN828197 (curve value).

Almonds and peanuts are a rich source of proteins, vitamins and unsaturated fatty acids. However, they can be also contaminated by mycotoxigenic fungi; a reason that has enhanced to investigate efficient strategies of management of these fungal contaminations. Some Lactic acid bacteria have been proven capable of inhibiting growth and mycotoxin production in livestock and transform it into nontoxic derivatives. In this work, four lactic acid bacteria (LAB) were tested for their abilities to inhibit the growth and mycotoxin production of Aspergillus flavus and Aspergillus carbonarius. Antifungal activity was evaluated in agar medium as well as in almonds and peanuts. Results showed that LAB significantly inhibited Aspergillus flavus and Aspergillus carbonarius in agar medium but none of the strains were able to completely inhibit fungal growth. The highest fungal growth inhibition was obtained using L. kefiri FR7 (51.67% and 45.56% growth inhibition of A. flavus and A. carbonarius, respectively). The cell-free supernatants (CFS) from LAB reduced fungal growth with average growth inhibitions ranging from 13.33% to 40.56% and 12.78% to 37.78% for A. flavus and A. carbonarius, respectively. We noted also that cell-free supernatants at pH7 (CFS-pH7) from the entire tested LAB did not inhibit fungal growth. L. kefiri FR7 was the most effective strain in mycotoxin suppression with a reduction percentage reaching 97.22%, 95.27% and 75.26% for AFB1, AFB2 and OTA respectively. Moreover, the inoculation of L. kefiri FR7 in almonds artificially contaminated with A. flavus decrease 85.27% of AFB1 and 83.94% of AFB2 content after 7 days of incubation. On the other hand, application of L. kefiri FR7 in peanuts artificially contaminated with A. carbonarius reduced OTA content to 25%. Our study revealed the potential use and application of L. kefiri FR7 in the control of fungi growth and mycotoxins production in almonds and peanuts.

A Staphylococcus lentus strain, isolated from Red sea water, was tested for decolorization capacity of Congo red, Evans blue, and Eriochrome Black T azo dyes. Biodegradation (100 mgl−1) of these dyes was studied within 24 h in Mineral Salt Medium solution containing 0.10 % (w/v) yeast extract and 7 mM of glucose at a pH of 7.2 and a temperature of 37 °C. Using a 2.2 × 106 CFU/mL inoculum size, S. lentus was able to decolorize these azo dyes with different degree. The staphylococcal biomass achieves approximately 100 % decolorization of Congo red and Eriochrome Black T by the end of treatment. FTIR and UV–Vis analyses confirm biodegradation potential of the tested strain. Moreover, the phytotoxicity of the dye solutions resulting from this treatment shows lower toxic nature compared to untreated solution of the respective dyes.

Synthesized Pyridin-2-yl hexanoate was screened for its antibacterial and antibiofilm activities using the broth microdilution method and XTT assay respectively. The obtained results revealed that synthesized molecule inhibited the growth of pathogenic bacteria (MICs value ranged from 80 to 640 μg ml−1). Moreover, it induced a strong antibiofilm effect against Gram positive cocci (BIC50 was 366, 378 and 412 μg ml−1 for Streptococcus mutans ATCC 25175, Streptococcus salivarius ATCC 13419 and Streptococcus oralis ATCC 6249 respectively). Basis on these results, pyridin-2-yl hexanoate may be considered as effective compound with antibacterial and antibiofilm activities.

Dental caries remains the most prevalent oral infectious disease worldwide. In this study, the antibacterial and the antibiofilm activities of five essential oils (EO's): eugenol (EUG), carvacrol (CAR), thymol (TYH), p-cymene (CYM) and γ-terpinene (TER) were tested (alone or in combinaison with tetracycline) against oral bacteria. In addition, their potential roles to enhance the accumulation of ethidium bromide (EtBr) in bacterial cells were tested. Our results indicated that EO's induced a selective antimicrobial activity. A synergistic effect of EO's and tetracycline (TET) was noticed with a reduction rate ranged from 2 to 8-fold. In addition, the efflux of EtBr was inhibited with a decrease in loss of EtBr from the bacteria. On the other hand a significant anti-biofilm activities of EO's (alone or combined with antibiotics) was noticed. In conclusion the tested EO's may be considered as a potential natural source with a resistance-modifying activity and may be applied to eradicate bacterial biofilm.

A strategy to reduce the deleterious effects of mycotoxins is to use dietary supplements that contain microorganisms that bind mycotoxins and diminish their gastrointestinal absorption. Novel strains were isolated from a Kefir culture and assessed for their mycotoxin adsorption and biotransformation ability. The most active strains were identified using DNA sequencing, and the stability of microorganism/mycotoxin complexes was evaluated using buffer solutions to simulate the pH conditions in the gastrointestinal tract. Our results showed that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B1 (AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The main strains that were capable of mycotoxin adsorption were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strain L. kefiri KFLM3 was the most active, adsorbing 80 to 100% of the studied mycotoxins when cultivated in milk. Nonetheless, the strain K. servazzii KFGY7 retained more mycotoxin after the desorption experiments (65, 69 and 67% for AFB1, OTA and ZEA, respectively). These findings suggest that Kefir consumption may help to reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. The isolated strains may be of interest for the development of fermented dairy products for human consumption that have a new probiotic characteristic, the adsorption of mycotoxins., This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of the UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), by the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte and by the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462). Luís Abrunhosa was supported by a grant, UMINHO/BPD/51/2015, from the project UID/BIO/04469/2013 financed by FCT/MEC (OE)., info:eu-repo/semantics/publishedVersion

Cardamom (Elettaria cardamomum) is a traditional aromatic plant for which several pharmacological properties have been associated. In this study, the antibacterial activity of two cardamom extracts (fruit and seeds), rich in volatile compounds, against major periodontal pathogens was evaluated. Moreover, the ability of the extracts to exert anti-inflammatory activity was tested. Both cardamom fruit and seed extracts exerted an antibacterial effect against Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia (minimum inhibitory concentrations: 0.5% [v/v], 0.25%, 0.062%, 0.125%, respectively and minimum bactericidal concentrations: 1%, 0.25%, 0.062%, 0.25%, respectively). The cell membrane of P. gingivalis was disrupted by a treatment with cardamom extracts suggesting the bactericidal mode of action. The extracts also inhibited biofilm formation although it correlated with a growth reduction. Moreover, the cardamom extracts significantly decreased the secretion of IL-1β, TNF-α, and IL-8 by lipopolysaccharide-stimulated macrophages. Evidence were brought that the anti-inflammatory activity may result from inhibition of the NF-κB signaling pathway. This study is the first to provide evidence that cardamom fruit and seed extracts through their antibacterial and anti-inflammatory properties may be therapeutic agents of interest against periodontal infections.

1-alkyl-2-pyridones, 2a-c, and 2-acyl-2-hydroxypyridines, 3a-b, were synthesized under ultrasonic irradiation. The synthesized compounds were characterized by 1HNMR and FTIR spectroscopy. DFT calculations were performed in order to study reactivity of the N and O-sites of 2-hydroxypyridine towards these reactions. The results showed that the electrophilicity index of the alkyl and acyl halide were found to be higher than that of 2-hydroxypyridine. Furthermore, these compounds were screened for antimicrobial activities and were found to be significantly inhibit bacterial and fungal strains. 1-hexyldecyl-2-pyridone (2c) and 2-acyl-2-hydroxypyridines (3a) displayed strong antibacterial activities towards Micrococcus luteus ATCC 10240 and Enterococcus faecalis ATCC 2921. Moreover compound 3a was found to effective inhibit Aspergillus fumigatus ATCC 204305 and Saccharomyces cerevisiae ATCC 9763. Hence to further validate the binding of these compounds, molecular docking studies were performed. The results revealed that compounds 2c and 3a were found to be interactive within the active sites of E. coli DNA gyrase enzyme and cytochrome P450, 14-α-sterol demethylase (CYP51) with good binding affinities. Furthermore, their comparative molecular docking results suggested to the compound 2c have a higher binding affinity than 3a with the selected receptors.

The persistence of pathogenic bacteria in the marine environment has been thoroughly investigated. The potential threat that these microorganisms pose to public health in recreational waters has always been a concern. In this study, the persistence and the response of Pseudomonas aeruginosa ATCC27853 to starvation and osmotic stress were studied after its incubation in sterilized seawater during 12 months. Three different colonial variants were isolated: A7 after one month, and A81 and A82 after 8 months of incubation period. The incubation effect on the bacterial phenotype and genotype were studied by analyzing modifications in morphology, antibiotic and metal resistance, molecular typing (PFGE and MLST), pigment production and virulence factors. The starved variants showed three different colony forms, but an indistinguishable PFGE pattern and belonged to ST155, as P. aeruginosa ATCC27853. The starved variants maintained the susceptibility to the 13 tested antibiotics, with the exception of the imipenem-resistant A82 strain, which also showed a small colony variant phenotype and the highest values of tolerance to the CuSO4 + NaCl combination. Significant differences were detected in the pigment production, the elastase activity and cytotoxic potential of the starved isolates in comparison to P. aeruginosa ATCC27853. Long-term exposure to stress, such as the incubation in seawater, was shown to induce different responses in P. aeruginosa, including virulent and resistant phenotypes.

Listeria monocytogenes is the main bacteria incriminated in contaminating cold storage food and ready-to-eat products. Survival of four L. monocytogenes food isolates was examined during freezing and cold storage. Slices of artisanal cheese were inoculated with Listeria strains and incubated at -20 °C. Their survival rate was recorded during the storage period. Then, transcript levels of four virulence genes (hlyA, iap, fri, and flaA) were evaluated using a semiquantitative reverse transcriptase PCR. Our results revealed that after 6 months of frozen storage, the number of L. monocytogenes cells had declined by 2.04 ± 0.1 log10 colony-forming units (CFU) g(-1), 2.52 ± 0.1 log10 CFU g(-1), and 2.58 ± 0.1 log10 CFU g(-1) for the strains S2, S3, and S4, respectively. Our data revealed that all the studied genes (hlyA, iap, fri, and flaA) were expressed after 6 months of incubation in artisanal cheese at -20 °C, and the transcript level has been affected by the factor freezing, whether for the reference strain ATCC 19115 or for other isolates. The iap gene expression was decreased for the four strains after 6 months of storage, and hlyA expression rate was consistently slightly lower. Transcript levels of fri and flaA genes were consistently higher in L. monocytogenes cells before cold exposure than in stressed cells and were significantly affected by the freezing process.