<i>Bacillus licheniformis</i> (MN900686) Mediated Synthesis, Characterization and Antimicrobial Potential of Silver Nanoparticles
Mohammad Shahzad TufailIram LiaqatSikander AliMobina UlfatAyesha ShafiAyesha SadiqaRiffat IqbalFatima Ahsan
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Abstract:
The use of bacteria in the synthesis of silver nanoparticles (AgNPs) emerges as an ecofriendly and exciting approach. In the present study, we reported the biosynthesis of AgNPs by using culture supernatant of the bacteria Bacillus licheniformis (MN900686). The biogenically synthesized AgNPs were confirmed by the change in the color of the culture filtrate from yellow to brown after the addition of AgNO3. Further characterization performed by means of UV vis-spectroscopy showed absorption peak at 414 nm which confirmed the formation of AgNPs. Fourier Transfer infrared (FTIR) confirmed the involvement of biological molecules in the formation of nanoparticles (NPs). The SEM revealed that the NPs have approximately 38 nm size. The agar well diffusion assay was used to determine antibacterial activity while tube dilution method was used to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The human pathogenic bacterial strains i.e., P. aeruginosa (MN900691) and B. subtilis (MN900684), were used as test strains. The anti-bacterial assay against test strains revealed that these NPs showed concentration dependent increased zone of inhibition (ZOI). The maximum ZOI at 25 µL of AgNPs was 20 mm against B. subtilis after 24 hours of incubation. One-way ANOVA test showed significant ZOI (p ≤ 0.05) against B. subtilis. The MIC was ranged from 4.3-6.6 μg/mL while MBC ranged from 8.3 to 6.6 μg/mL. Overall, this study suggested that the biogenically synthesized NPs are an effective alternative source of antimicrobials against pathogenic bacteria.Keywords:
Bacillus licheniformis
Minimum bactericidal concentration
Agar diffusion test
Silver nanoparticle
Pathogenic bacteria
Aim: The aim of this in vitro study was to compare the antimicrobial efficacy of calcium hydroxide-based sealer (Apexit Plus), zinc oxide eugenol-based sealer (Endoflas FS) and resin-based sealer (EndoRez) root canal sealers against Enterococcus faecalis microbial type culture collection (MTCC) 439 and Candida albicans MTCC 239 using agar diffusion test. Materials and Methods: In the present study, 20 Mueller Hinton agar (MH agar) plates were employed. Three wells were made by removal of agar at equidistant points and filled with root canal sealers according to manufacturer's instructions. The strains of the bacteria and fungi used in this study were E. faecalis MTCC 439 and C. albicans MTCC 227. Both micro organisms were grown at 37°C for 24 h in MH Broth and seeded into MH agar to produce a turbidity of 0.5 on the McFarland scale, which corresponds to a concentration of 10 8 CFU/mL. This MH broth was used as a second layer. The seeded agar was then added over the plates immediately after the insertion of sealer cements. After incubation, the diameters of zones of inhibition around the plates were measured. Results: The results were statistically analyzed using two way ANOVA test. Against both the micro organisms used in this study, Endoflas FS showed the largest zones of inhibition followed by Apexit Plus and EndoRez. Conclusion: Within the limitations of this study, it can be concluded that: Root canal sealers showed different inhibitory effects depending on their types and microbial strains tested. Against Enterococcus faecalis and Candida albicans, zinc oxide based sealers showed the highest microbial zones of inhibition followed by the calcium hydroxide based sealer and resin based sealer respectively
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It summarizes the studies about the inhibitory efficacy and the sterilizing efficacy of the dry distillated oil made from seeds of hawthorn on five enteric pathogenic bacteria. To these five bacteria (Staphylococcus aureus, Escherichia coli, Salmonella paratyphi, Shigella flexneri, Pseudomonas aeruginosa), the Minimum inhibitory concentration (CMIC) is about 025%～05%, and the Minimum bactericidal concentration(CMBC) is about 10%～20%. The antimicrobes efficacy varied with the concentration of the dry distillated oil, the reaction time and the kinds of the bacteria.
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The effects of crude extracts of seeds of Azadarichta indica against pathogenic Staphylococcus aureus, Staphylococcus pyogenes, Escherichia coli andPseudomonas aeruginosa obtained as clinical isolates from patients diagnosed with eye and ear infections were investigated using the agar well diffusion method . The growth of all the isolates were inhibited, though to varying degrees, with gram-positive more susceptible than gram-negative bacteria. The control laboratory strains were more sensitive to the toxic effects of the crude extracts than the corresponding test bacteria. Hexane extracts were more effective, producing larger zones of growth inhibition sizes and smaller MIC and MBC values, than the aqueous extracts. The MIC values ranged from 1.59 -25 mg/ml while the MBC values ranged from 3.17-50 mg/ml. The extracts were more effective under elevated temperature and acidic conditions. The ability of the crude extracts to inhibit the growth of such pathogenic bacteria that frequently cause eye and ear infections as those used in this study is an indication that the neem seed has the potential and can be used as a source for new broad spectrum oral antibiotics. The result obtained in this study validates the use of the neem seeds in traditional medicine to treat infectious conditions especially those involving the eye and ear.
Key words: Azadarichta indica, neem seeds, pathogenic, disc diffusion, validates, infectious condition.
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Plants with medicinal value produce certain chemical elements known as phytochemicals that have antibacterial activity. The study was aimed at determining the antibacterial activity of Vernonia amygdalina against bacterial isolates using agar well diffusion method. In addition, the phytochemicals analysis of the extracts was also determined. The phytochemical analysis showed the presence of saponins, steroids, terpenoids, tannins, alkaloids, and flavonoids. The result of Vernonia amygdalina showed that the average zones of inhibitions observed against these bacterial ranges from 6-22mm. The highest zone is also exhibited against E. coli with average diameter of zone of inhibition of 22mm. At 100mg/ml concentration for Samonella, the zone of inhibition was recorded to be 21mm while at 12.5mg/ml there was no inhibition. At 25mg/ml and 12.5mg/ml, against Pseudomonas there was no inhibition. In other to further confirm the activity of these plant extracts, the minimum inhibitory concentration and minimum bactericidal concentration was determined and the result showed that the extract exerted good antibacterial activity on all the test organisms at different concentration. The result of minimum inhibitory concentration ranges from 10 to 12.5mg/ml and that of MBC ranges from 5 to 20mg/ml. It is worthy to note that MBC values is greater than that of minimum inhibitory concentration. The study provides insight into the antibacterial activities of the plant extracts and its use in the treatment of bacterial infections.
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This study aimed at evaluating the health benefits of popular Moringa oleifera leaf. The aqueous and methanolic extracts of the leaf at two different concentrations (1:1 and 1:2) was used to determine the phytochemical screening and its antibacterial activity. Escherichia coli, Streptococcus pneumonia and Staphlococcus aureus were used in this study, applying agar diffusion methods. The phytochemical screening indicated presence of secondary metabolites such as alkaloid, flavonoids, anthraquinoines, tannins and phenol in both extracts making it to have antibacterial potentials. Both extract showed remarkable activity against the growth of the selected bacteria; nevertheless, the methanol extract had more antibacterial activity than the water extract, more so the extracts were discovered to be more active at higher concentration. The water extract was not active at low concentration, that is 1:1 but had diameter zone of inhibition of 10 mm each for 1:2 concentration. The minimum inhibition concentration (MIC) that inhibits these bacterial ranged between 1:4 and 1:16 and the minimum bactericidal concentration (MBC) that kills the growth of the bacterial isolates completely was 1:16. The result of this study showed that M. oleifera could be a valuable antibacterial drug in the treatment of infections caused by the test organisms. Key words: Agar diffusion method, aqueous and methanol extracts, secondary metabolites, zone of inhibition, minimum inhibition concentration (MIC), minimum bactericidal concentration (MBC).
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Aims: Out of many properties that an endodontic disinfecting agent should possess, the most important is that of having a wide range of antibacterial efficacy. This study has been performed to see the effect of different agents on the bacterial microflora and to see how efficient they are against them. Our study has used 3 different agents (Chlorohexidine, Sodium Hypochlorite, and Neem extract) and compared their efficacy against bacterial microflora.
Study Design: Experimental study design
Place and Duration: The study was conducted in the Department of Endodontics at Fatima Jinnah Dental College and Hospital, Karachi, Pakistan from February 2020 to March 2020.
Methodology: Infected samples from individuals were collected through paper points and then allowed to be cultured and incubated on blood agar plates at 37 degrees in an incubator for 24 hours. The colonies were then identified through the gram staining procedure and grown on MHA agar to conduct the disk diffusion test for sensitivity. Individual zones of inhibition for irrigants were measured and compared against each other.
Results: A total of 36 infected samples were included in the study out of which 12 samples were irrigated with chlorohexidine, 12 with sodium hypochlorite, and 12 with neem extract. there was a statistically significant difference in mean diameters of the inhibition zone observed between the three groups for the mean inhibition zone (F=12.28, P=0.001).
Conclusion: Chlorohexidine showed greater efficacy against bacterial microflora, compared to both sodium hypochlorite and neem extract.
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The use of bacteria in the synthesis of silver nanoparticles (AgNPs) emerges as an ecofriendly and exciting approach. In the present study, we reported the biosynthesis of AgNPs by using culture supernatant of the bacteria Bacillus licheniformis (MN900686). The biogenically synthesized AgNPs were confirmed by the change in the color of the culture filtrate from yellow to brown after the addition of AgNO3. Further characterization performed by means of UV vis-spectroscopy showed absorption peak at 414 nm which confirmed the formation of AgNPs. Fourier Transfer infrared (FTIR) confirmed the involvement of biological molecules in the formation of nanoparticles (NPs). The SEM revealed that the NPs have approximately 38 nm size. The agar well diffusion assay was used to determine antibacterial activity while tube dilution method was used to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The human pathogenic bacterial strains i.e., P. aeruginosa (MN900691) and B. subtilis (MN900684), were used as test strains. The anti-bacterial assay against test strains revealed that these NPs showed concentration dependent increased zone of inhibition (ZOI). The maximum ZOI at 25 µL of AgNPs was 20 mm against B. subtilis after 24 hours of incubation. One-way ANOVA test showed significant ZOI (p ≤ 0.05) against B. subtilis. The MIC was ranged from 4.3-6.6 μg/mL while MBC ranged from 8.3 to 6.6 μg/mL. Overall, this study suggested that the biogenically synthesized NPs are an effective alternative source of antimicrobials against pathogenic bacteria.
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This study synthesized silver N-methyl chitosan (Ag-NMC) and tested it for its antimicrobial and antifungal activity. Ag-NMC was characterized by FTIR, XRD, measured for its molecular weight (MW), solubility, and toxicity. The antimicrobial activity was tested by the agar diffusion method, determining the MIC (Minimum Inhibitory Concentration), MBC (Minimum Bactericidal Concentration) against Staphylococcus aureus and Escherichia coli bacteria, and determining the Minimum Fungicidal Concentration (MFC) against the fungus Candida albicans. The results showed that Ag-NMC had MW, solubility, and LC50 of 555.65 g/mol, 50 mg/mL, 945,492 mg/L, respectively. The diameter of the inhibition zone from the resulting diffusion test showed that Ag-NMC had better antimicrobial activity than N-methyl chitosan (NMC) and chitosan. The MIC, MBC, and MFC values of Ag-NMC were always lower than that of NMC and chitosan.
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Screening and isolation of proteolytic bacteria were carried out from soil samples of Ikogosi warm spring (SW, Nigeria). Eighteen isolates were positive on skim milk agar (10%) of which fifteen produced protease in culture broth. Three isolates, identified as Bacillus macerans IKBM-11, B. licheniformis IKBL-17 and B. subtilis IKBS-10, were selected for further study. These Bacillus species could grow up to 65°C within a broad pH range of 5 to 10 with an optimal growth temperature and pH at 60°C and 8.0, respectively. For the three Bacillus species, protease production occurred between 37°C and 65°C and pH 5 to 10. Maximum growth and maximum enzyme production was observed at 48 h when grown in 50 ml medium (pH 8.0) under shaking condition at 60°C. The results showed that Bacillus species under study are good producers of extracellular protease at high temperature. This might be an indication that proteases produced would be thermostable. Keywords Protease; proteolytic bacteria; Bacillus macerans; Bacillus licheniformis; Bacillus subtilis African Journal of Biotechnology Vol. 4 (8), pp. 776-779
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Bacillaceae
Proteolytic enzymes
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Eight different preservation methods for eighteen common pathogenic bacteria were compared for their preservation time and their influences upon their biological characteristics. The results indicated: freeze-drying method could do the longest preservation (at least 15 years) while beef broth agar plate method did the shortest (only 2 to 3 months). If the preservation time was put into order, it went like this: freeze-drying method semisolid freeze methodsemisolid slope covered with paraffin oli method semisolid slope method beef broth covered with paraffin oil method blood agar plate method beef broth agar plate method. However, even the same method had different preservation time for different pathogenic bacteria. The pathogenic bacteria whose preservation time was within a year had no changes in their biological characteristics while some pathogenic bacteria such as corynebacterium diphtheriae, staphylococcus aureus, salmonella paratyphi A, salmonella paratyphi B, which was preserved by means of freeze-drying method, had some changes in their biological characteristics.
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