Property and Antibacterial Spectrum of Partially Purified Enterocin Produced by Entrocinogenic Enterococcus faecalis Isolated from the Gut of Cockroach

Enterocins are small, heat stable and antimicrobial agents are directed against a broader spectrum of bacteria. Isolation, partial characterization and antibacterial activity of partially purified enterocin from Enterococcus faecalis form the aim of this study. The protein content of crude enterocin of the enterocin from highest producing strain was 16.6 mg/ml and its activity was 170 AU/ml. The antibacterial activity of crude enterocin produced by Enterococcus faecalis was tested on both Gram-positive bacteria which include Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus and Bacillus cereus, while Gram-negative bacteria were Klebsiella pneumoniae, Serratia marcescens, Pseudomonas aeruginosa, Proteus mirabilis, Listeria monocytogenes and Salmonella Typhi. The effect was pronounced on Gram-negative than Gram-positive pathogens. The enterocin was stable at 40, 50, 60 and 70oC and over a pH range between 4.0 and 8.5. It has bactericidal effect and cause rapid inhibition of the growth of the sensitive strains. No change was observed in the enterocin bioactivity after treatment with sodium chloride, magnesium chloride, sodium dodecyl chloride, ethylene diamine tetra-acetic acid and urea. In conclusion, since it can withstand a broad range of temperature and pH, it can be used as biocontrol of both pathogenic and spoilage organisms

Evaluation of Antimicrobial Activities of Albizia zygia DC Leaf Extracts against Some Clinically Important Pathogens

In vitro antimicrobial effects of aqueous, ethanolic and methanolic extracts of Albizia zygia dc leaf against some clinically important bacterial and fungal pathogens were reported. Following extraction of air dried A. zygia dc leaf by different solvents (water, ethanol and methanol), the filtrates were concentrated in vacuo using rotary evaporator. The antibacterial and antifungal activities were assayed by agar diffusion method on Muller-Hinton Agar (Himedia Laboratories Pvt. Ltd, Vadhani) and Potato dextrose agar (Oxoid, Ltd, Bashingstoke, Hampshire, England) plates, respectively. Standard methods were used to determine the time-kill assay of methanolic extract, the amount of protein and potassium ion leaked in the test bacteria. All the extracts (aqueous, ethanolic and methanolic) did not possess any antifungal property. The aqueous and ethanolic extracts were not active against the test bacteria.  Methanolic extract showed significant antibacterial effect on greater percentage of the test bacteria with diameter of zones of inhibition ranging from 3.0 to 21.12 mm at 30 mg/ml and 5.2 to 25.4 mm at 50 mg/ml of the extract. The minimum inhibitory concentration (MIC) of the methanolic extract ranged between 3.75 and 15.3 mg/ml. The methanolic extract of A. zygia leaf showed a significant bactericidal and bacteriostatic activity against Bacillus subtilis and Klebsiella pneumoniae over the time range (15-120 min) at different MIC concentrations. The time-kill assay of methanolic extract of A. zygia against K. pneumoniae was dose dependent. The amount of protein leaked was higher in B. subtilis than K. pneumoniae at 30 µg/ml (P = 0.05). There was no significant difference in the level of  K+ leaked at 15 µg/ml (1 X MIC) and 30 µg/ml (2 X MIC) of the extract. The methanolic leaf extract of A. zygia showed a considerable inhibitory effect on greater percentage of the test bacterial pathogens, but did not possess antifungal property. The antibacterial potential could be harnessed in the folklore management of infections caused by the susceptible test bacteria.

Effects of different substrates on the morphological characteristics and proximate content of Pleurotus pulminarius

Morphological characteristics and proximate content of Pleurotus pulminarius cultivated on different substrates were investigated. The substrates used are cotton waste, sawdust, palm fruit waste, paper, mixture of sawdust and palm fruit waste and mixture of cotton waste and paper (1:1) were sterilized and inoculated with Pleurotus pulminarius spawn (sorghum-produced) aseptically, incubated under controlled temperature and humidity before exposure to sunlight. Length and, diameter of stalk and pileus were measured during stages of harvest. Protein, fat, carbohydrate, crude fibre, ash and moisture content were determined by standard methods. Pleurotus pulminarius appeared on saw dust and cotton waste; paper, combination of saw dust and palm fruit waste, mixture of paper and cotton waste; and palm fruit waste after 2 days, 3 days and 5 days respectively. For the first stage of harvest, Saw dust had the highest length of stalk (cm) of 5.40 ± 0.63 and the lowest value of 2.70 ± 0.14 was obtained from palm fruit waste only. Mixture of paper waste and cotton waste has the highest diameter of stalk (3.25 ± 0.61 cm) (second harvest), the lowest diameter of stalk (0.4 ± 0.1 cm) was recorded for palm fruit (third harvest). Cotton waste had the highest diameter of pileus (7.88 ± 1.29 cm) (first harvest) while the lowest value (1.78 ± 0.63 cm) was obtained from mushroom harvested on the mixture of paper and cotton waste (second harvest). Pleurotus pulminarius harvested on mixture of paper and cotton waste has the highest percentage protein of 40.54% while the least value 28.79% protein was obtained from mushroom harvested on saw dust. Mushroom harvested on saw dust has the highest percentage fat content of 0.99% and palm fruit waste gave the lowest percentage fat of 0.74%. Palm fruit waste displayed the highest percentage ash and crude fibre contents of 4.38% and 4.81% respectively while cotton and paper wastes had the least ash and crude fibre content of 1.81% and 0.47% respectively. Saw dust gave the highest percentage carbohydrate of 62.54%s. Moisture content of 0.51% was obtained for mushrooms harvested on Palm fruit waste, Sawdust and mixture of sawdust and palm fruit waste as the least value while the mixture of paper and cotton waste has the highest moisture content of 3.49%. The study concluded that mushroom can serve as cheap source of food supplements such as protein, crude fibre, ash (micro and macro nutrients), fat, carbohydrate and moisture with beneficial bioconversion of agricultural and other wastes materials in the environment. Key words: Pleurotus pulminarius, cotton, sawdust, palm fruit, paper, wast

Antibiotic resistance and Molecular characterization of Salmonella in diarrhoeal patients’ faeces in south-western Nigeria

The study reports the prevalence of multiple antibiotic resistance (MAR) and molecular chacterization of resistance (BlaCTX and GyrA) genes in Salmonella recovered from stool samples of diarrhoeal patients in Ile-Ife, Osun state, Nigeria. Salmonella was cultured on molten Salmonella and Shigella agar (Oxoid, Ltd, Bashingstoke, Hampshire, England) plate at 370C. Susceptibility of isolates to antibiotics was done on Mueller Hinton (Himedia lab Ltd, Vadhani) by disk diffusion technique. Detection of plasmid DNA in multiple antibiotic resistant isolates was carried out by alkali lysis (TENS) method and resistance genes (BlaCTX and GyrA) were detected by the polymerase chain reaction. A total of 69 Salmonella (S.Typhimurium(82.6 %), S.Typhi(10.1 %) and S.ParatyphiA (7.3 %)) were cultured from 187 diarrhoeal stool samples analysed. Resistance was mostly to nitrofurantoin (100%), ceftriazone (97.2 %), and gentamicin (94.2 %) among others.  Sixty seven (97.1 %) of the Salmonella isolates were resistant to at least two different classes of antibiotics with 32 antibiotypes. Multiple plasmids of molecular weights (1.46 - 23.13 kbp) and resistance genes (GyrA-282 bp, blaCTX-480 bp) were detected in the representative MAR isolates. The prevalence of MAR Salmonella in diarrhoeal patients’ stool samples is high in the study area with attendant public health and economic loss consequences. Keywords:Salmonella, diarrhoea, antibiotic resistance, plasmid, resistance gene

Antibiotic-resistant commensal Escherichia coli in faecal droplets from bats and poultry in Nigeria

The prevalence of antibiotic resistance and plasmid carriage among commensal faecal Escherichia coli isolates of bats, broilers and free-range chickens in Ile-Ife, Osun State, Nigeria was studied. A total of 125 E. coli isolates were recovered from the fresh faecal samples of bats, broilers and free-range chickens on eosin methylene blue agar plates and characterised using standard biochemical tests. The susceptibility of the isolates to antibiotics was performed using the disk diffusion method. All isolates developed resistance to antibiotics to varying degrees; resistance to augumentin, amoxicillin and tetracycline was significantly higher (p0.05) with the exception of ciprofloxacin, pefloxacin gentamicin and ofloxacin. A total of 90% of the bat isolates developed multiple antibiotic resistance with 28 multiple antibiotic resistance patterns. The free-range chicken and broiler isolates displayed 10 and 38 multiple antibiotic resistance patterns, respectively. Resistance was mostly plasmid-mediated with molecular weights ranging between 0.91 kb and 40.42 kb. Antibiotic resistance and plasmid carriage among the commensal E. coli isolates studied was relatively high and may be implicated in zoonotic infections