Test Bacterial Species Research Articles

Antibacterial Properties of Young and Mature Mango Leaves (Mangifera indica) Extract on Some Clinical Isolates

Aim: This study was carried out to investigate the antibacterial properties and efficacy of mango (Mangifera indica) leaf extracts on some clinical isolates as test rganisms. 
 Study Design: The study employed statistical analysis of the data and interpretation
 Place and Duration of Study: Young and mature mango leaves were collected from the Botanical Garden, Kenule Beeson Saro-Wiwa Polytechnic, Bori, Nigeria, and taken to the laboratory for analyses. 
 Methodology: The samples were dried in an oven at 80oC for 3 days. Thereafter, 50 g of each ground mango leaf (young and mature leaves) were soaked separately in 500 ml of water, ethanol (95% v/v), and acetic acid (99.9% v/v) respectively for another 3 days. The soaked materials were filtered through Whatman No. 1 filter paper into sterile beakers and evaporated to dryness in a water bath at 80oC. The dried extracts obtained were reconstituted with water at concentrations of 100, 75, 50, and 25 mg/ml. Test organisms, Escherichia coli, Staphylococcus aureus, Salmonella typhi, Proteus mirabilis, Bacillus cereus, and Pseudomonas aeruginosa were obtained after proper laboratory screening of isolates from the diagnostic laboratory of the Rivers State University Teaching Hospital, Port Harcourt, Nigeria, for confirmation of identity and storage in universal bottles in a refrigerator. Sensitivity tests were carried out with the agar well diffusion method against the test organisms, using tetracycline as the standard control drug, with cultures incubated accordingly. The measured zones of inhibition were compared with the controls and interpreted as resistant, intermediate, or susceptible to mango extracts in accordance with the interpretive guidelines published by the National Committee for Clinical Laboratory Standards (NCCLS). Assay for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was also carried out.
 Results: Results obtained showed that acetic acid young leaf extract at 100mg/ml produced 50 % susceptibility and 50 % intermediate response of test bacterial species. Generally, at 100 mg/ml, acetic acid young leaf extracts yielded 50% susceptibility and 50% intermediate response among both Gram-positive and Gram-negative bacteria. Ethanolic extracts gave 100% intermediate sensitivity of Gram-negative species and 50% each of resistant and intermediate response in Gram-positive forms. Aqueous extracts also produced no susceptibility among the test organisms as there was 100% resistance. Extracts of mature mango leaves of all solvents and at all concentrations used yielded no susceptibility response among the test bacterial species on the NCCLS scale. Minimum inhibitory and bactericidal concentrations were found to range from 25 mg/ml to 50 mg/ml. Additionally, it was observed that the sensitivity of organisms to mango extracts increased with concentration.
 Conclusion: In conclusion, acetic acid has a better extracting potential than ethanol and water as a solvent for the extraction of mango parts. More so, young mango leaves extracted with acetic acid possess higher broad-spectrum antibacterial properties than the mature mango leaves extracted from the same plant. It is therefore recommended that young mango leaves, extracted with acetic acid, be used for the treatment of microbial infections at concentrations not below 50 mg/ml.

Comparative Study of the Antimicrobial Activity of Clove Oil and Clove Extract on Oral Pathogens

Objective The main objective of the present study was to do the comparative study of clove oil and clove extract on the oral micro-biota causing dental caries and also to assess the antifungal activity. Materials and Methods The antimicrobial activity of clove oil and clove extract was assessed against Halobacterium sp., Lactobacillus sp., Pseudomonas sp., Micrococcus sp. and Streptococcus mutans (major causative bacteria of dental plaque) by the paper disc diffusion method. For each extract three replicate trials were conducted against each organism. The antifungal activity of clove oil and extract was also assessed against seven fungal species (Aspergillus niger, A. fumigatus, Aspergillus sp., Alternaria sp., Rhizomucor sp., Rhizopus sp. and Penicillium sp.) by agar disc diffusion method. Results Both clove oil and clove extract was found to exhibit broad spectrum of antibacterial activity inhibiting all the ten test bacterial species involved in dental caries. Clove oil produced maximum inhibition zone of diameter (IZD) against themajor causative bacteria of dental plaque as compared to clove extract, thereby, showing that clove oil possesses strong bactericidal activity against oral pathogens. The highest inhibition zone of diameter was observed by clove oil as compared to clove extract against the test fungal species Conclusion The clove oil has the potential to be used as a natural antibacterial agent for oral pathogens.

Evaluation of antibacterial efficacy of Ocimum sanctum L. against certain bacterial species and phytochemical analysis

In the present study antibacterial efficacy of aqueous and methanol extract obtained from leaves and stem of Ocimum sanctum L. was evaluated against certain test bacterial species viz. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus cereus. It is a traditional medicinal herb, commonly used for the treatment of various human health disorders. The antibacterial activity was determined by using agar well diffusion method. Among the solvent extracts tested, aqueous extract of leaves exhibited higher antibacterial activity as compared to methanolic extract of leaves. Maximum antibacterial activity was recorded 17.6 mm against Bacillus cereus and minimum value was recorded 14 mm against S. aureus. Maximum antibacterial efficacy of O. sanctum leaves was found 7.3mm against P. aeruginosa and minimum value was 5mm against B. cereus in methanolic extract. Similar trend has been observed in extract of stem of O. sanctum in aqueous and methanolic solvent. The antibacterial efficacy has been found nil in methanolic extract. However in aqueous extract moderate activity has been recorded i.e. 9.3 mm against E.coli and minimum 7.3 mm against K. pneumoniae. The trend of phytochemicals revealed non significant variation. Phytochemical analysis of leaves and stem extracts of O. sanctum revealed the presence of various phytoconstituents i.e. alkaloids, flavonoids, saponins, tanins, glycosides.

Bacterial growth inhibition and antioxidant potentials of leaf infusions of (Moringa oleifera), locust beans (Parkia biglobosa) and bitter leaf (Vernonia amygladina)

This study was aimed at assessing the bioactive potential of aqueous leaf infusions of three plant species, moringa (Moringa oleifera), locust beans (Parkia biglobosa) and bitter leaf (Vernonia amygdalina). The antimicrobial studies were carried out using the agar diffusion method against the selected isolates. For growth rate studies, known quantities of the respective crude leaf infusions only or in combination with ascorbic acid were added to sterile nutrient broth before inoculating with the respective test bacterial species and incubated. Growth was then monitored every 1 h, for a 10 h duration and after 24 h. Antimicrobial and growth rate studies were carried out using five bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae). Results of the agar diffusion procedure revealed bitter leaf infusion showing inhibition against P. aeruginosa, S. aureus, K. pneumoniae and E. coli. The locust bean leaf infusion showed inhibition against E. coli only while the moringa leaf infusion inhibited the growth of P. aeruginosa, S. aureus, K. pneumoniae and E. coli. For the growth rate studies, all test bacterial species showed extended lag period in nutrient broth that contained the leaf infusions or a combination of the leaf infusions and ascorbic acid. None of the infusions was able to completely stop the growth of the test bacterial species for a 24 h growth period. In nutrient broth that contained the locust bean leaf infusion only, longer lag period of the test bacterial species was observed than in medium that contained both the leaf infusion and ascorbic acid. All the leaf infusions showed antioxidant activities when investigated for their ability to scavenge free radicals. The study was able to show the antimicrobial and antioxidant potentials of the infusions, hence their possible application as antimicrobial agents.

Chemical Constituents, Antioxidant and Antimicrobial Activity of Syzygium aromaticum

Phenolic constituents from residue after clove oil extraction and oil on oral micro-biota causing dental caries werestudied. Both clove oil and extract were found to exhibit broad spectrum of antibacterial activity inhibiting all the ten testbacterial species involved in dental caries. Clove oil produced inhibition zone of diameter (IZD) of 19.0, 19.0, 18.0, 17.0 and 15.0 mm against Halobacterium sp., Lactobacillus sp., Pseudomonas sp., Micrococcus sp. and Streptococcus mutans, respectively as compared to extract from residue (15.0, 14.0, 16.0, 15.0 and 13.0mm). The inhibitory effect was concentrationdependent and has the potential to be used as a natural antibacterial agent. The antifungal activity of oil and extractassessed against seven fungal species (Aspergillus niger, A. fumigatus, Aspergillus sp., Alternaria sp., Rhizomucor sp., Rhizopus sp. and Penecillium sp.) and both were able to inhibit the test fungal strains but clove oil was superior in efficacy. The highest IZD 42.0mm was observed against A. niger by oil while extract produced IZD 30.0mm against Alternaria sp. The chemical constituents of clove oil analyzed by GC-MS showed 35 constituents with major ingredients as eugenol (81.6%), eugenyl acetate (5.2%), -caryophyllene (2.3%) and as minor β-farnesene (0.98%), β-phellandrene (0.74%), linalool (0.73%) and γ-Terpinene (0.69%). Phenolic compounds identified from extract of residue left after oil extraction were biflorin, kaempferol, rhamnocitrin, myricetin, gallic acid and ellagic acid. The free radical quenching antioxidant activity varied from 75.8 to 89.6% and was comparable to synthetic antioxidants (BHT and BHA).

Antibacterial Activities of Five Medicinal Plants in Ethiopia against Some Human and Animal Pathogens.

Objective To evaluate the in vitro antibacterial activities of five plant extracts which have been used as traditional medicines by local healers against three multidrug resistant bacteria, namely, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Results The highest mean zone of inhibition (4.66 mm) was recorded from methanol extract of Calpurnia aurea (Ait.) Benth. at a concentration of 200 mg/ml against S. aureus, followed by Croton macrostachyus Del. (4.43 mm) at the same dose and solvent for the same bacterial species, while methanol and chloroform extracts of E. brucei Schwein. did not inhibit growth of any bacterial species. The lowest value (100 μg/ml) of minimum inhibitory concentration (MIC) was observed from both methanol and chloroform extracts of C. aurea (Ait.) Benth. against all the three bacteria. The results of the positive control had no statistically significant difference (P > 0.05) when compared with crude extracts of C. aurea (Ait.) Benth. at concentration of 200 mg/ml against S. aureus. Conclusion The results of the present study support the traditional uses of these medicinal plants by the local healers. Except Erythrina brucei Schwein., all the plants investigated in this study exhibited antibacterial activities against the test bacterial species. Further researches are needed to be conducted to evaluate efficacy of these medicinal plant species on other microbes in different agroecological settings and their safety levels as well as their phytochemical compositions.

Effect of nitrogen source concentration on decolouration rates of laboratory dyes by immobilized cells of two bacterial species.

The aim of this study was to assess the effect of sodium nitrate concentration on the decolouration of laboratory dyes (bromothymol blue, crystal violet, eosin blue, eosin yellow and methylene blue), by alginate immobilized cells of Pseudomonas aeruginosa and Bacillus subtilis. The sodium nitrate concentrations used in the study were 5, 10, 15 and 20g/L. A control setup that contained no sodium nitrate was also studied. During incubation, aliquot samples were withdrawn from each flask every 24 for 144h duration for the estimation of decolouration rate of the dyes, using standard procedures. The results revealed remarkable decolouration of the bromothymol blue and crystal violet in presence of the P. aeruginosa occurring at sodium nitrate concentrations of 10 and 15g/L, respectively. In the case of media that was inoculated with the B. subtilis cells, although no remarkable decolouration of the bromothymol blue and crystal violet was observed throughout the period of incubation, highest decolouration were observed at sodium nitrate concentration of 5 and 10g/L, respectively. For the eosin blue and methylene dyes, no remarkable decolouration were observed in presence of the test bacterial species at the respective sodium nitrate concentrations. Highest decolouration of the eosin yellow was however observed in media with sodium nitrate concentration of 5g/L. The results of this study could be applied in scale up studies and continuous process, for implementation in biological decolouration of dye effluents.

Limonia acidissima L. leaf mediated synthesis of silver and zinc oxide nanoparticles and their antibacterial activities

Green chemistry is a novel method for the synthesis of silver and zinc oxide nanoparticles. The present investigation focused on synthesis of biogenic silver and zinc oxide nanoparticles. They were assayed for their antibacterial activities against test bacterial species. The results revealed that the silver nanoparticles showed the maximum zone of inhibition 15.16, 15.5 and 13.33 mm at 400 μg/mL to S. aureus, S. typhi and P. aeruginosa respectively, when compared to the Erythromycin. While zinc oxide nanoparticles showed less activity in comparison to silver nanoparticles owing to the agglomeration of nanoparticles. It is evident from our investigation that silver nanoparticles could be used as an antimicrobial due to their intrinsic properties in biomedical application and food packing industries.

Design, synthesis and antimicrobial evaluation of pyrimidin-2-ol/thiol/amine analogues

BackgroundPyrimidine is an aromatic heterocyclic moiety containing nitrogen atom at 1st and 3rd positions and play an important role to forms the central core for different necessity of biological active compounds, from this facts, we have designed and synthesized a new class of pyrimidin-2-ol/thiol/amine derivatives and screened for its in vitro antimicrobial activity.Results and discussionThe synthesized pyrimidine derivatives were confirmed by IR, 1H/13C-NMR, Mass spectral studies and evaluated for their in vitro antimicrobial potential against Gram positive (S. aureus and B. subtilis), Gram negative (E. coli, P. aeruginosa and S. enterica) bacterial strains and fungal strain (C. albicans and A. niger) by tube dilution method and recorded minimum inhibitory concentration in µM/ml. The MBC and MFC values represent the lowest concentration of compound that produces in the range of 96–98% end point reduction of the used test bacterial and fungal species.ConclusionIn general all synthesized derivatives exhibited good antimicrobial activity. Among them, compounds 2, 5, 10, 11 and 12 have significant antimicrobial activity against used bacterial and fungal strains and also found to be more active than the standard drugs.Graphical abstractPyrimidine is an aromatic heterocyclic moiety containing nitrogen atom at 1st and 3rd positions and play an important role to forms the central core for different necessity of biological active compounds, from this facts, we have designed and synthesized a new class of pyrimidin-2-ol/thiol/amine derivatives and screened for its in vitro antimicrobial activity. The synthesized pyrimidine derivatives were confirmed by IR, 1H/13C-NMR, Mass spectral studies and evaluated for their in vitro antimicrobial potential against Gram positive (S. aureus and B. subtilis), Gram negative (E. coli, P. aeruginosa and S. enterica) bacterial strains and fungal strain (C. albicans and A. niger) by tube dilution method and recorded minimum inhibitory concentration in µM/ml. The MBC and MFC values represent the lowest concentration of compound that produces in the range of 96–98% end point reduction of the used test bacterial and fungal species.

Demonstration of in vitro antibacterial activity of the popular cosmetics items used by the Dhaka locality

ObjectiveTo demonstrate the antibacterial activity of cosmetic products commonly used by the community of Dhaka metropolis. MethodsA total of 10 categories of cosmetic samples (with a subtotal of 30 brands) were subjected to microbiological analysis through conventional culture and biochemical tests. Agar well diffusion method was used to determine the antibacterial trait in the tested samples which was further confirmed by the minimum inhibitory concentration method. ResultsAll samples were found to be populated with bacteria and fungi up to 10 CFU/g and 103 CFU/g, respectively. Growth of Staphylococcus spp., Pseudomonas spp. and Klebsiella spp. was recorded as well. Conversely, 7 out of 30 items were found to exhibit the in vitro antibacterial activity against an array of laboratory test bacterial species including Staphylococcus spp., E. coli, Bacillus spp., Pseudomonas spp., Klebsiella spp. and Listeria spp. Consequently, all the samples showed antibacterial activity below the concentration of 0.46 mg/mL as found in the minimum inhibitory concentration test. ConclusionsOverall, the presence of huge microbial population in cosmetic products is not acceptable from the point microbiological contamination level. The antibacterial trait of these items, in contrary, may draw an overall public health impact.

Bioautography screening of Jatropha gossypsifolia L. Leaves against the Gram positive organisms

Jatropha gossypifolia L ., belonging to the family Euphorbiaceae is traditionally used in curing various ailments. It is commonly called as cotton leaf, physic nut and Belly ache. In Tamil commonly called as Kattamanakku. Humans are natural hosts for many bacterial species that colonize the skin as normal flora. Staphylococcus aureus and Streptococcus epidermis is infrequent resident flora, but they account for a wide variety of bacterial pyodermas. Predisposing factors to infection include minor trauma, pre-existing skin disease, poor hygiene, and rarely, impaired host immunity. The present study deals with the antibacterial activity and phytochemical screening of Jatropha gossypifolia . Sequential extraction was carried out using solvents such as chloroform, ethanol, and water from leaf of the plant were investigated for preliminary phytochemical and antibacterial property. Results of the study showed that all the extracts had good inhibitory activity against Gram-positive test organism. Although all four extracts showed promising antibacterial activity against test bacterial species, yet maximum activity was observed in ethanol extract. The minimum inhibitory concentration ranged in between 64 to 1024 ? g/ml. Evaluation of phytochemicals such as alkaloids, flavonoids, saponin, tannin, glycosides, phenolic compound, proteins and amino acids revealed the presence of most of constituents in polar extracts of aqueous. All the findings exhibit that the leaf extracts have broad-spectrum activity and suggest its possible use in treatment of infectious diseases.

The Effect of Temperature on Nitrate and Phosphate Uptake from Synthetic Wastewater by Selected Bacteria Species

Aim: The aim of this study was to ascertain the effect of temperature on nutrient uptake ability of four bacterial species. Methodology: A total of four bacterial species (Klebsiella sp., Pseudomonas sp., Lysinibacillus sp. and Staphylococcus sp.) were used for the study. The media used for the investigation was synthetic wastewater. Four different temperatures (25oC, 30oC, 35oC and 40oC) were used for the investigation. The study was carried out under shake flasks conditions. Immediate after inoculation with the respective test bacterial species and every 24 h for a 96 h incubation time, aliquot wastewater samples were removed from the flasks for the estimation of total phosphate, nitrate, pH and growth rate, using standard procedures. Results: The results revealed phosphate and nitrate removal ranges of 10.84 % to 55.55 % and 90.67 % to 97.27 %, respectively in the presence of the Klebsiella sp. In the presence of the Pseudomonas sp, Lysinibacillus sp. and Staphylococcus sp., phosphate removals Original Research Article British Microbiology Research Journal, 4(3): 328-342, 2014 329 ranges of 0.36 % to 46.98 %, 11.89 % to 50.80 % and 2.74 % to 51.21 % were observed, respectively. For nitrate concentrations, removal levels that ranged from 2.19 % to 92.95 %, 0.97 % to 23.12 % and 7.56 % to 91.66 % were observed in the presence of Pseudomonas sp, Lysinibacillu ssp. and Staphylococcus sp., respectively. All the test bacterial species showed some measure of efficiency in phosphate removal. For nitrate removal, the Lysinibacillus sp. did not exhibit remarkable nitrate removal ability at any of the temperatures. In addition, the optimum temperatures for phosphate removals were observed to be 30oC to 40oC for the Klebsiella sp. and Pseudomonas sp; and 30oC to 35oC for the Lysinibacillus sp. and Staphylococcus sp. For nitrate removal, optimum temperatures for removal were observed to be 25oC to 40oC, for the Klebsiella sp and 25oC to 35oC, for the Pseudomonas sp. and Staphylococcus sp. Conclusion: The study was able to reveal the optimum temperatures for phosphate and nitrate uptake in synthetic wastewater by the test bacterial species.

An efficient catalyzed Green synthesis of substituted coumarins using Potassium dihydrogen phosphate Catalyst and studies their Anti-microbial activities

The Coumarine heterocyclic ring is common feature of various bioactive compounds such as calanolides, lipid-lowering agents. The Chemists all over the globe are motivated not only for the environmentally benign synthesis of new products but also to develop green synthesis for existing chemicals. Coumarins, the most important classes of fluorescent molecules constitute important structural features present in a number of bioactive natural products. Recent studies have been revealed that coumarin and the derivatives exhibit several other medicinal applications such as anti-coagulants, antifungal, insecticidal, hypnoticsphytoalexins, HIV protease & inhibitors. Coumarins act as in intermediate for the synthesis of various biologically active molecule such as coumarones, and fluorocoumarins . Thus the synthesis of coumarins is of continuing interest.Potassium dihydrogen phosphate a commercially available environmentally benign catalyst non-toxic widely used for the synthesis of the substituted coumarin .The scope of this catalyst has not been fully explored, but can be used as buffer, neutralizing agent. Owing to the numerous advantages associated with cheap and non-hazardous catalyst, and also realizing g the importance of coumarin herein we would like to focus the eco -friendly method for his synthesis of derivatives of coumarin using cheaper and commercially available acid catalysts Potassium dihydrogen phosphate and also by the Knoevenagel condensation under microwave irradiation. The synthesized coumarin derivatives were screened in Vitro anti-microbial efficacy testing. In vitro anti-microbial efficacy testing was carried out by broth dilution method by broth dilution method as mentioned in Pharmaceutical Microbiology. For anti-bacterial activity, MullerHintonmedium was used as the nutrient media. Test bacterial species used are Escherichia coli ,(ATCC 10148), Staphylococcus aureus(NCTC 3750), Pseudomonas aeruginosa (Fisher'Immunotype IV), test fungi species used are Aspergilliusniger(ATCC 16404) and Candida albicans (ATCC 10231) in different concentrations starting from 25ppm .All the coumarin derivatives are active against the test bacteria and fungai in different concentrations. This paper focuses is to develop environment friendly reactions, simple, highly efficient and high yielding protocol for the synthesis of coumarin derivatives using Potassium dihydrogen phosphate as a catalyst.Even though a number of modified methods have been reported, but many of them suffer from drawbacks such as unsatisfactory yields, longer reaction time, and corrosive reagents. Thus the development of an efficient and versatile method to synthesis of coumarin derivatives is an active ongoing research and there is a scope further improvement towards milder reaction condition and yield. This methodology offers significant improvements for the synthesis of derivatives of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic conventional catalysts and solvents. Therefore owing the importance of Potassium dihydrogen phosphate a facile catalyst used for the green synthesis of new derivatives of coumarin .

Antibacterial and Antioxidant Activities of Various Medicinal Plants Used in Oriental Medicine

The antibacterial activities of the ethanol extracts of 35 medicinal plants were screened against Escherichia coli, Bacillus cereus, and Staphylococcus aureus by following standard antimicrobial susceptibility testing procedures. The ethanol extracts of Coptis chinensis and Glycyrrhiza uralensis showed antibacterial activity against all three test bacterial species. The screened extracts were also tested for their antioxidant activities using the DPPH free radical scavenging activity assay, and for their cytotoxic and antioxidant activity in vitro using an assessment of cell viability on mouse embryonic fibroblast cells. The ethanol extracts of both C. chinensis and G. uralensis showed good radical scavenging antioxidant properties and attenuated the rate of cell death caused by oxidative damage. Our results showed that C. chinensis and G. uralensis are promising sources of natural products with good antibacterial and antioxidant activities.

Screening Antimicrobial Peptides In Vitro for Use in Developing Transgenic Citrus Resistant to Huanglongbing and Citrus Canker

Huanglongbing {HLB [associated with Candidatus Liberibacter sp. (CLas)]} and asiatic citrus canker {ACC [causal organism Xanthomonas citri ssp. citri (XCC)]} are bacterial diseases that seriously threaten sustainability of the Florida citrus (Citrus sp.) industry. Sweet orange (Citrus sinensis) and grapefruit (Citrus paradisi) are highly susceptible to ACC and improvement through conventional breeding is a long-term process, making transgenic solutions attractive. No strong HLB resistance has been identified within cultivated citrus scion types: creation of transgenic citrus that would permit economic citrus production where HLB is endemic is a high priority. Little is known about the HLB pathosystem and thus broad-spectrum antimicrobial peptides (AMPs) have been the focus for current work, and identification of safe and effective transgenes is essential to our efforts. In vitro assessment of minimum inhibitory concentration (MIC) for 44 AMPs was conducted using Sinorhizobium meliloti and Agrobacterium tumefaciens as surrogates for the unculturable CLas because they are closely related alpha proteobacteria (class Alphaproteobacteria). XCC is also a gram-negative bacterium and was included in these analyses in anticipation that HLB and ACC resistance can be achieved with the same AMP transgene if expressed using non-tissue-specific promoters. Twenty AMPs from diverse sources were initially tested. AMPs with the lowest MICs included tachyplesin I from horseshoe crab (Tachypleus tridentatus), SMAP-29 from sheep (Ovis aries), D4E1 and D2A21 (which are synthetic AMPs derived through evaluation of critical amino acid residues in AMPs, overall peptide structure, and AMP effectiveness), the human (Homo sapiens) LL-37, and the honeybee (Apis mellifera) venom AMP melittin. These AMPs inhibited growth of all three test bacterial species at 1 μM or less. An additional 20 synthetic AMPs were designed based on structures of the most effective AMPs and seven of these showed effectiveness at 1 μM or less across all three test bacteria. Most AMPs were comparable in effectiveness across the three bacterial species, but some species × AMP interactions were observed. Hemolytic activity was assessed by exposure of porcine erythrocytes (from Sus scrofa) to the AMPs. Hemolysis from most AMPs was not significantly different from water, whereas melittin was highly hemolytic.

Antimicrobial activity of selected natural products against Gram-positive, Gram-negative and Acid-fast bacterial pathogens

Recurring epidemics of drug resistant bacterial diseases such as those caused by mycobacteria (tuberculosis and non-tuberculous infections), staphylococci (methicillin-resistant <em>Staphylococcus aureus</em> or MRSA infections) and various Gram-negative enterobacteria (enterobacterial infections) have reinforced the need to search for alternative antimicrobials. In this context, we investigated the anti-bacterial potential of nine different natural products and compared them with the antibiotic controls, using three test bacterial species, representing the Gram-negative (<em>Escherichia coli</em>), Gram-positive (<em>Staphylococcus epidermidis</em>), and Acid-fast (<em>Mycobacterium smegmatis</em>) pathogen groups. Six of the nine products showed detectable but variable zones of inhibition (mm2). The anti-bacterial activity (mm2 per 100 mg) of the extracts from the four solid natural products was in the following order for all three pathogen groups: Mint (<em>Mentha arvensis</em>) leaf extract, 264-930>Mushroom (<em>Agaricus bisporus</em>) cap extract, 112-241>Turmeric (<em>Curcuma longa</em>) root extract, 4-10>Ginger (<em>Zingiber officinale</em>) root extract, 3-9. For the liquid products, the activity measured on 100 μL aliquots was in the following order: Eucalyptus (<em>Eucalyptus globules</em>) oil, 264-1044>Mustard (<em>Brassica campestris</em> L. var. brown sarson) oil, 45-96. Taken together, these results indicated the highest activity in Mint extract and Eucalyptus oil against all three test organisms. However, the individual test strains showed the following variable order of susceptibility: Mint extract (<em>M. smegmatis</em>><em>E. coli</em>><em>S</em>. <em>epidermidis</em>); Eucalyptus oil (<em>M. smegmatis</em>><em>S. epidermidis</em>><em>E</em>. <em>coli</em>). Based on these results it can be concluded that Mint leaves and Eucalyptus oil have an unusually broad spectrum activity and may, therefore, be promising sources of new broad spectrum antimicrobials.

Biodegradable and biocompatible epoxidized vegetable oil modified thermostable poly(vinyl chloride): Thermal and performance characteristics post biodegradation with Pseudomonas aeruginosa and Achromobacter sp.

The increased production of municipal solid waste by the disposal of plastic materials heightens the urgency to develop biodegradable materials for daily use. In vitro-biodegradation study on poly(vinyl chloride) (PVC) plasticized by epoxidized Mesua ferrea L. seed oil at three different weight percentages (PVC/ENO ratio of 75/25, 50/50 and 25/75) was conducted by using Pseudomonas aeruginosa and Achromobacter sp. bacteria. The test bacterial species were able to grow on the polymer matrix by using it as a source of energy; however the pristine PVC did not support the microbial growth. The PVC/ENO material of 25/75 ratio showed the highest percent (%) of biodegradation compared to other tested systems. The bacterial count and the dry biomass post 180 days of inoculation in 25/75 plasticized PVC suggested bacterial growth at the expense of degradation of the system. The tensile strength of 25/75 PVC/ENO system, post 180 days of inoculation by Pseudomonas aeruginosa and Achromobacter sp. decreased by about 53% and 43% respectively. Further, surface erosion phenomenon and structural change of the matrix after bacterial growth, as studied by FTIR and SEM analysis of PVC/ENO of 25/75 ratio exhibited noticeable deterioration post 180 days of inoculation.

Antibacterial activity of Phoenix dactylifera L. leaf and pit extracts against selected Gram negative and Gram positive pathogenic bacteria

The crude methanol, acetone and water extracts of leaves and pits of three varieties ofPhoenix dactylifera were tested for antibacterial action against selected Gram positive and Gram negative pathogenic bacteria. Barring Enterococcus faecalis, the acetone and methanol extracts showed good antibacterial activity against Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Shigella flexeneri, Staphylococcus aureus, and Streptococcus pyogenes, whereas the water extract had very little effect on all test bacterial species and there was almost negligible effect on P. aeruginosa. Pits extracts of all three varieties of P. dactylifera were found to be more effective than leaves extracts. Results clearly showed that S.pyogenes was most sensitive pathogen to the crude extracts and had shown maximum zone of inhibition. Minimum inhibitory concentration (MIC) for S. pyogenes was found to be 1.3, 1.1, 1.6 and 1.4 mg/ml for methanol leaves and pits extracts and acetone leaves and pits extracts, respectively. Key words: Date palm, Phoenix dactylifera L, antibacterial, crude extracts.

Antibacterial activities and phytochemical analysis of Cassia fistula (Linn.) leaf

Cassia fistula Linn. which belongs to family Leguminosae is a medium-sized tree and its different parts are used in ayurvedic medicine as well as home remedies for common ailments. Sequential extraction was carried out using solvents viz. petroleum ether, chloroform, ethanol, methanol and water from leaf of the plant were investigated for preliminary phytochemical and antibacterial property. Results of the study showed that all the extracts had good inhibitory activity against Gram-positive test organism. Although all five extracts showed promising antibacterial activity against test bacterial species, yet maximum activity was observed in ethanol extract. The minimum inhibitory concentration ranged in between 94 to 1 500 μg/ml. Evaluation of phytochemicals such as alkaloids, flavonoids, carbohydrates, glycosides, protein and amino acids, saponins, and triterpenoids revealed the presence of most of constituents in polar extracts (ethanol, methanol, and aqueous) compared with nonpolar extracts (petroleum ether and chloroform). Furthermore, the ethanol extract was subjected to TLC bioautography and time-kill study against Staphylococcus epidermidis. All the findings exhibit that the leaf extracts have broad-spectrum activity and suggest its possible use in treatment of infectious diseases.

Comparative Antibacterial Studies On The Root, Stem Bark And Leaf Extracts Of Parkia Clappertoniana.

The research on medicinal plants is gradually gaining popularity due to millions of people depending on the use of different parts of these materials for various ailments.The antibacterial activity of hot and cold water and ethanolic extracts of the root, stem and leaf of Parkia clappertonia against Escherichia coli ATCC 11775, Pseudomonas aeruginosa ATCC10145, Staphylococcus aureus ATCC 12600 was evaluated using agar-well diffusion and agar dilution methods. All the organisms were susceptible to all the extracts with the diameter of zones of inhibition ranging between 14 mm – 27 mm for hot water extracts, 12 mm – 22 mm for cold water extracts and 12 mm – 25 mm for ethanolic extracts. The Minimum Inhibitory Concentrations ranged between 2.5 mg/ml – 20.0 mg/ml. The rate of kill of the test bacterial species by hot water extract was concentration dependent. Saponin, flavonoids, tannin, glycoside, alkaloid and anthraquinone were the phytochemical constituents detected from the Parkia clapatoniana root, stem and leaf extracts. The implications of these findings in the medicinal use of Parkia clapertoniana are discussed.