Expression and characterization of α-Amylases from penicillium citrinum with bread as growth substrate

In an attempt to enhance the industrial production of α-amylases in the tropics, sterile fresh bread was inoculated with spore suspensions of Penicillium citrinum at 25 oC. Extracellular α-amylases were produced and subjected to partial purification by ammonium sulphate precipitation and dialysis. Further purification by gel filtration and ion-exchange chromatography was engaged. The molecular weights of the α-amylase fractions obtained and estimated by gel filtration using Sephadex G-100 were approximately 56,234 Daltons, 53,089 Daltons and 11,885 Daltons. The apparent Michalis-Menten constant (Km) values for the hydrolysis of starch by the purified α-amylase fractions were approximately 8.3 mg/ml, 10 mg/ml and 7.14 mg/ml respectively. Optimum activities were at 30 oC for one of the fractions and 35 oC for the other two fractions and were at pH 5.5 and pH 6.0. The activities of the α-amylase fractions produced by the fungus were stimulated at varying degrees by NaCl, KCl, CaCl2 and MgCl2 but inhibited by Ethylene Diamine Tetraacetic Acid (EDTA), mercuric chloride (HgCl2) and 2,4-dinitrophenol (DNP). The α-amylase fractions were sensitive to heat, losing all their activities within twenty minutes of heating at 80 oC. The industrial production of α-amylases should be encouraged in the tropics using bread as a cheap source of substrate.Keywords: α-Amylase, expression, bread, purification, characterization

Epidemiology of methicillin-resistant Staphylococcus aureus among hospitalized patients and apparently healthy individuals in Ekiti and Ondo States, Nigeria.

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) in hospitalized patients and apparently healthy individuals was investigated in two western states of Nigeria using standard microbiological methods. One thousand and two hundred non-repeat isolates of S. aureus were recovered from the subjects. At varying degrees the isolates were resistant to cotrimoxazole (54.8%), augmentin (36.9%), pefloxacin (35.9%), gentamycin (28.3%), erythromycin (24.9%), vancomycin (10.3%), ofloxacin (5.2%) and ciprofloxacin (0.3%). One hundred and fifty six (13.0%) were resistant to methicillin out of which 4.8% and 8.2% were from healthy individuals and patients respectively. There was no correlation between prevalence of MRSA and age or sex (p < 0.05). There was no correlation between the antibiotic resistance pattern in MRSA from healthy volunteers and patients (P < 0.05). A total of 9.0%, 12.2% and 21.2% of the MRSA were resistant to 3, 4 and 5 antibiotics respectively. Antibacterial activities of five biocides examined using agar diffusion method showed that 38.5%, 53.2%, 59.6%, 61.5% and 71.8% of the MRSA were not inhibited by Izal®, Morigad®, Septol®, Dettol® and Purit® respectively, at concentrations two times higher than the in-use concentration. This finding points to the fact that MRSA occurs among patients and in the communities in the study areas, which calls for a public health concern and awareness

Antibiotic resistant bacteria in faecal samples of apparently healthy individuals in Ado-Ekiti, Nigeria

The occurrence of antibiotic-resistant bacteria in faeces of apparently healthy individual volunteers was investigated. Faecal samples were collected from 216 individuals comprising 138 adults (70 males and 68 females) and 78 children aged between 4 months and 42 years (mean age was 30.2 months). Individuals on antibiotics were excluded from the study. Faecal samples were examined microbiologically for the presence of bacteria resistant to commonly employed antibiotics. Three hundred and eleven bacterial isolates were recovered; the bacteria detected included Escherichia coli (16.6%), Enterobacter sp. (13.6%), Salmonella sp. (13.2%), Proteus sp. (12.6%), Serratia sp. (11.9%), Klebsiella sp. (9.3%) and Citrobacter sp. (7.9%). Others included Hafnia sp. (3.6%), Providencia sp. (3.0%), Shigella sp. (3.0%), Edwardsiella sp. (2.6%), Yersinia sp. (2.0%) and Pseudomonas sp. (0.7%). Overall resistance to antibiotics was generally high; resistance to streptomycin (59.0%) was highest, while it was least to gentamicin (39.5%). High proportion (96%) of the isolates showed multiple antibiotic resistance (MAR) with 151 phenotypes. Journal of Science and Technology(Ghana) Vol. 27 (1) 2007: pp. 51-6