ABSTRACT
Aim: To determine the antibiotic reaction and adhesion pattern of antimicrobial homofermenting LAB strains in the fermenting slurries of kunu zaki. Study Design: ANOVA. Inhibition of indicator lawn used ≥10mm inhibition as antibiotic susceptible. Adhesion was measured by staining and quantifying recorded as percentage and index values. Place and Duration of Study: Department of Microbiology, Federal University of Technology Akure and Biotechnology Unit, Federal Institute of Industrial Research, Oshodi, Nigeria between June, 2012 and December, 2012. Methodology: Kunu-zaki drinks were produced using spontaneously fermenting cereal grains of Digitaria exilis (acha), Sorghum bicolour (sorghum) and Pennisetum americanum (millet) in composite and non-composite proportions. LAB isolates were obtained on MRS agar. Homo-fermenting isolates were identified to species level using the API 50 CHL test kit. Antibiotic sensitivity testing on the identified isolates followed the modified standard Kirby-Bauer procedure on MRS agar (pH 7.4) using the disc diffusion technique with selected antibiotics. For quality control of the antibiotics, sensitive reference strains S. aureus ATCC 25923 and E. coli ATCC 25922 obtained from the Nigeria Institute of Medical Research were used. Adhesion and antimicrobial properties were determined using standard method. Results: Antimicrobial substances produced by the eight LAB isolates inhibited the growth of four selected human pathogens in vitro. All eight LAB isolates were resistant to amoxicillin, gentamycin and ciprofloxacin. L. plantarum126, L. paracasei subsp paracasei339 and Pediococcus damnosus32 were resistant to erythromycin whilst all others were susceptible. L. plantarum126 and L. paracasei subsp paracasei339 were resistant to all antibiotics tested. All LAB isolates demonstrated high in-vitro intestinal epithelial cell adhesion potential. Conclusion: LAB antimicrobial activity may not be affected if kunu zaki is consumed simultaneously with these antibiotic therapies. However, if these LAB strains are intended for use as kunu-zaki starter cultures, it is important that they should be further carefully examined for inability to transfer antibiotic resistance genes to food pathogens.
ABSTRACT
Antioxidant and antimicrobial potentials of extracts obtained from four wild mushrooms, Termitomyces clypeatus (TCE), Termitomyces robustus (TRE), Lentinus subnudus (LSE) and Lenzites species (LZE) collected in Nigeria were investigated. LSE and LZE displayed good scavenging activity against 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH) and ferrous ion radicals at concentration of 2 mg/mL. However, TRE and TCE exhibited better superoxide anion scavenging effect at 2 mg/mL. All extracts (TCE, TRE, LSE and LZE) had comparable scavenging effect on hydroxyl radicals as butylated Hydroxytoluene (BHT) used as control. Moreover, extracts from the wild mushrooms were able to inhibit the growth of all indicator organisms at concentrations between 12.5 mg/mL to 100 mg/mL. LSE and LZE, however, showed better antimicrobial effect on the indicator organisms. The results suggest that extracts obtained from the four wild mushrooms may serve as sources of new bioactive compounds with effective antioxidant and antimicrobial activity.
Foram investigadas as propriedades antioxidantes e antimicrobianas de extratos obtidos de quatro cogumelos selvagens da Nigéria: Termitomyces clypeatus (TCE), Termitomyces robustus (TRE), Lentinus subnudus (LSE) and Lenzites species (LZE). LSE e LZE, na concentração de 2 mg/ml, apresentaram boa atividade sequestrante contra 2,2'-difenil-b-picrilhidrazil (DPPHò) e radicais ferrosos. Entretanto, TER e TCE a 2 mg/ml apresentaram melhor efeito sequestrador de anions superóxido .Todos os extratos apresentaram feito semelhante de seqüestro de radicais hidroxila como BHT usado como controle. Além disso, todos os extratos dos cogumelos selvagens, na concentração de 12,5 mg/ml até 100 mg/ml, foram capazes de inibir a multiplicação de todos os microrganismos indicadores testados, mas LSE e LZE apresentaram efeito antimicrobiano mais intenso. Os resultados sugerem que os extratos obtidos dos quatro cogumelos selvagens podem ser fontes de novos compostos bioativos com atividade antimicrobiana e antioxidante.