MOSP - Macao Scientific Publishers

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Influence of cultural conditions on hydrogen peroxide production by lactic acid bacteria isolated from some Nigerian traditional fermented foods

I. A. Adesokan*, Y. A. Ekanola and B. M. Okanlawon

Abstract: In this study, influence of cultural conditions on hydrogen peroxide production by lactic acid bacteria was investigated. Leuconostoc mesenteroides produced the highest quantity (0.024 L) of hydrogen peroxide while Lactobacillus plantarum produced the lowest amount (0.016 g/L) in normal MRS. The effect of temperature on hydrogen peroxide production was determined and the result showed that Leuc. mesenteroides produced the highest quantity (0.024 g/L) at 30°C while L. brevis produced the lowest amount (0.012 g/L) of hydrogen peroxide at 45°C. Leuc. mesenteroides produced the highest amount of hydrogen peroxide (0.032 g/L) when mannitol was used as the carbon source while Lactobacillus delbrueckii and Lactobacillus fermentum produced the lowest amount (0.020 g/L) when glucose was used as the carbon source. Furthermore, Leuc. mesenteroides produced the highest amount of hydrogen peroxide (0.033 g/L) when potassium nitrate was used as the nitrogen source while L. fermentum and L. delbrueckii produced the lowest amount (0.020 g/L) when yeast extract was used as the nitrogen source. Hydrogen peroxide produced by Leuc. mesenteroides has the highest zone of inhibition against Pseudomonas aeruginosa while hydrogen peroxide produced by L. plantarum had the lowest zone of inhibition against Staphylococcus aureus.[...] Read More.

Keywords: Hydrogen peroxide production, lactic acid bacteria, temperature.

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Acetoin production associated with the increase of cell biomass in Bacillus pumilus ATCC 14884

Zijun Xiao*, Shuling Qiao, Cuiqing Ma and Ping Xu

Abstract: Some of Bacillus strains, especially Bacillus pumilus, were the best acetoin producers. This study attempts to disclose the mechanisms of vigorous acetoin excretion using B. pumilus ATCC 14884 as a model strain. The production of acetoin by this strain has been studied under a variety of conditions. Glucose was found to be a much better substrate than citrate, pyruvate, succinate, or fumarate for acetoin production. Malonate was used to slow down the Krebs cycle and the addition of 0.10 M malonate was found to inhibit cell growth slightly, but reduce the production of acetoin by 13%. The addition of 100 g/L NaCl strongly reduced cell growth and acetoin formation. On the other hand, 200 g/L glucose reduced the rate of cell growth, but led to the largest final acetoin production of all the conditions studied. Linear relationships between acetoin accumulation and cell biomass, which increased in the lag and arithmetic growth phases were found when glucose was used as the carbon source, which corroborated acetoin as a primary metabolite. Metabolite study indicated that there were few minor pathways for by-products. Acetoin was utilized as a preferential carbon source without the catabolite repression of glucose, suggesting that the main physiological function of acetoin excretion is an energy-storing strategy in this species.[...] Read More.

Keywords: Acetoin, biomass, association, metabolism, Bacillus pumilus.

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Investigating the effects of various additives on surface activity and emulsification index of biosurfactant resulting from broth media of Bacillus subtilis PTCC 1023

Full Length Research Paper

Abstract: Surfactants are amphipathic molecules which reduce surface tension and are widely used in pharmaceutical, cosmetic and food industries. In the present study, the production of biosurfactant by Bacillus subtilis PTCC 1023 was studied. B. subtilis was grown in the nutrient broth medium and biosurfactant production was evaluated by measuring the surface tension and emulsification index (E24) each 24 h. The bacterium’s biosurfactant production was investigated in different status with variable factors such as incubation time, temperature, aeration rate and presence of several additives. Then the best fermentation condition was investigated for maximum biosurfactant production and finally biosurfactant identity was investigated using some chemical and spectroscopy methods. The maximum biosurfactant production by B. subtilis PTCC 1023 was obtained when it was grown in brain-heart broth medium containing FeSO4 (4×10-3 M), MnSO4 (1.3×10-3 M), starch (4%) and castor oil (4%) which incubated in a 300 rpm rotary shaker at 30°C for 24 h. Lipopepetide natures in this biosurfactant was confirmed by biochemical and spectroscopic methods.[...] Read More.

Keywords: Bacillus subtilis, biosurfactant, emulsification index, surface tension.

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Effect of cultural components on antimicrobial activity of bacteriocin produced by bacteria isolated from gut of poultry

Qiuju Wang, Yizhe Cui, Dale Lackeyram, Ling Yuan, Jili Xu, Wenmei Wang and Li Xu*

Abstract: The effects of various carbon and nitrogen sources and enzymes on the antibacterial activity of Enetrococcus faecium bacteriocin L17 (3.5 kDa) isolated from poultry gut and confirmed by polymerase chain reaction (PCR) and 16S rDNA sequencing was carried out. The bacteriocin exhibited antibacterial activity against both gram-negative and gram-positive bacteria, as well as some funding such as Micrococcus flavus and Candida mycoderma, but had no effect on Lactic acid bacteria (LAB). The metabolite was stable in the presence of lipolytic or glycolytic substances and over a wide range of temperatures and its activity was also enhanced in the presence of 1 - 1.5% Tween80, 0.1% macrogol as well as various carbon (lactose) and nitrogen (lactose combined with beef extract and soy peptone) sources. Poteolytic enzymes however, completely inactivated the metabolite. These results are promising because the trend today is to employ eubiotic or symbiotic products and their use in the poultry industry could be a natural way to protect the flocks against potential pathogens.[...] Read More.

Keywords: Bacteriocin, medium composition, antimicrobial activity, poultry.

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Investigation of endophytic and symbiotic features of Ralstonia sp. TSC1 isolated from cowpea nodules

Papa Saliou Sarr*, Takeo Yamakawa, Satoru Asatsuma, Syunsei Fujimoto and Masao Sakai

Abstract: Ralstonia sp. TSC1 previously isolated from cowpea nodules was tagged with gfp gene by transposon insertion. The resultant gfp-tagged Ralstonia sp. TSC1 showed no difference in physiological properties such as growth rate, exopolysaccharide formation and colony morphology. When it was co- inoculated with compatible bradyrhizobial strains, the observation of fluorescence microscopy showed that TSC1 strains were colonized in subsurface of cowpea nodules and stems. In addition, TSC1 positively and negatively modulated symbiotic performance with the bradyrhizobia in terms of nodulation and symbiotic nitrogen fixation. The results suggested that Ralstonia sp. TSC1 is an endophyte with beneficial, neutral or detrimental effects on cowpea plants when in presence of effective bradyrhizobia.[...] Read More.

Keywords: Ralstonia sp., cowpea, endophyte, green fluorescent protein, bradyrhizobium, nodulation.

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Antimicrobial activity of Rhaponticum acaule and Scorzonera undulata growing wild in Tunisia

Houda Ben Abdelkader*, Karima Bel Haj Salah, Kaouthar Liouane, Olfa Boussaada, Karima Gafsi, Mohamed Ali Mahjoub, Mahjoub Aouni, Ahmed Nourreddine Hellal and Zine Mighri

Abstract: This study examined the in vitro antibacterial and antifungal activities of the extracts (butanolic, ethyl acetate, petroleum ether and the product H2) of 2 plants belonging to the Asteraceae family: Rhaponticum acaule L. and Scorzonera undulata L. Butanolic and ethyl acetate extracts of the Rhaponticum acaule plant showed a moderate antibacterial activity against 3 of the tested strains; Staphylococcus aureus, Escherichia coli and Enterococcus fecalis while Proteus mirabilis, Pseudomonas aeruginosa and Citrobacter freundeï were resistant to the extracts. The product H2 showed an antibacterial activity against S. aureus, C. freundeï and E. fecalis. From the results of the antifungal activity, we observed that butanolic and ethyl acetate extracts of R. acaule showed a strong inhibition against Trichophyton rubrum with inhibition percentage of 56.25 and 78.75%, respectively. Butanolic extract showed a moderate inhibition of Microsporum canis, Scopulariopsis brevicaulis and Aspergillus fumigatus while ethyl acetate extract showed low inhibition. The aerial part ethyl acetate extract of S. undulata seemed to be more active than the petroleum one. It showed an antibacterial activity against all bacteria strains tested except for E. coli. For antifungal activity, the petroleum ether and ethyl acetate extracts of the aerial part inhibited strongly all tested fungi. The roots extracts from S.undulata show weak antimicrobial activities compared with the aerial parts extracts of the same plant.[...] Read More.

Keywords: Rhaponticum acaule L, Scorzonera undulata L, Asteraceae, antibacterial activity, antifungal activity, Tunisia.

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In vitro assessment of aqueous and ethanolic extracts of some Nigerian chewing sticks on bacteria associated with dental infections

David O. M., Famurewa O.,* and Olawale A. K.

Abstract: The antimicrobial efficacy of aqueous and ethanolic extracts of ten Nigerian chewing sticks was investigated using standard methods. These extracts were tested against six bacteria associated with dental infections; they are Actinomyces vercosus, Neisseria sicca, Streptococcus mutans, Staphylococcus aureus, Lactobacillus salivarius and Moraxella catarrhalis. Generally, ethanolic extract had higher activity on the test organisms than the aqueous extracts. The zone of inhibition of Viellaria paradoxical (Gaertn. F) ranged between 5 and 13 mm. M. catarrhalis was most susceptible bacterium to the extracts. A. vercosus was resistance to the extract of P. guineense (Schum & Thonn), A. indica (A. Juss) and M. accumunata (G. Don).[...] Read More.

Keywords: Chewing sticks, oral hygiene, pathogens, antibacterial activity

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Conjunctivitis among children in a teaching hospital in South-West of Nigeria: Role of Staphylococcus aureus as an aetiologic agent and its antibiogram

O. A. Adeyeba, M. C Anorue, O. A. Adefioye*, Y. O. Adesiji, A. A. Akindele, O. S. Bolaji, and I. K. Adewuyi

Abstract: This study was done at the University College Hospital Ibadan, Nigeria between January and June, 2006. It was designed to determine the incidence and prevalence of Staphylococcus aureus in conjunctivitis in the Ophthalmology clinic of the hospital as well as the antibiotic sensitivity profile to chloramphenicol. A total of 210 swabs were gram-stained and cultured bacteriologically. 158 were positive for bacterial pathogens while 26 were bacteriologically sterile. A total of 174 bacterial isolate both in pure and mixed culture were isolated and 72 of the isolates were S. aureus. The age group < 1 year had the highest occurrence rate of 44.4%, followed by age group 1 - 5 years (30.6%) while the age group 6 - 10 years had the least (11.1%). More males (63.9%) than females (36.1%) were infected (p < 0.05). Susceptibility test result showed that gentamicin, ciprofloxacin, pefloxacin, erythromycin were active against s. aureus and are therefore, recommended as first line drugs. Chloramphenicol (61.1%) showed moderate activity against the organism.[...] Read More.

Keywords: Prevalence, incidence, staphylococcus aureus, ophthalmology, chloramphenicol.

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Effect of time and relative humidity on the microbial load and physical quality of cashew nuts (Anacardium occidentale L) under storage

A. A. Onilude, R. O. Igbinadolor* and S. M. Wakil

Abstract: Post harvest deterioration by microbes due to improper storage condition is considered to be the major cause of spoilage of most seeds like cashew nuts. Roasted cashew nuts were subjected to 4 different storage conditions with different relative humidity of 30, 70, 80 and 90%, respectively, for a period of 12 days. Each storage condition was examined for microbial growth, crispiness, pH changes, moisture content and other parameters. 8 fungal species identified as Aspergillus niger, Rhizopus sp., Penicillium sp., Trichoderma sp., Botryodiplodia sp., Fusarium compactum, Aspergillus flavus and Aspergillus ochraceous and 3 bacteria isolates identified as Bacillus subtilis, Bacillus licheniformis and Staphylococcus sp., were obtained. The most predominantly encountered organisms were fungal isolates of Rhizopus sp and A. niger with percentage frequency of 34.9 and 32.6%.[...] Read More.

Keywords: Relative humidity, preservation, microbial load.

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Sero-epidemiology of brucellosis in small ruminants in Plateau State, Nigeria

W. J. Bertu*, I. Ajogi, J. O. O. Bale, J. K. P. Kwaga and R. A. Ocholi

Abstract: A sero-epidemiological study of brucellosis in small ruminants was carried out in Plateau state to determine the status of the disease. A total of 1347 serum samples from 851 goats and 496 sheep systematically collected from nine randomly selected Local Government Areas (LGA) of the state were tested for brucella antibodies using Rose Bengal plate test (RBPT) and serum agglutination test (SAT). The result revealed brucellosis prevalence of 14.5% in sheep and 16.1% in goats, respectively. The prevalence varied from one LGA to another and between sheep and goats in each LGA. In goats, the highest prevalence of 19.7% was recorded in Mangu LGA while the lowest (10.3%) was in Shendam LGA. In sheep, Quanpan LGA had the highest prevalence of 23.5% while Bassa LGA had the least prevalence of 6.3%. The prevalence in goats was higher compared to sheep but this was not statistically significant (p > 0.05). The widespread brucellosis seroprevalence in Plateau state is of great economic and public health significance. There is the need to embark on control and eradication of small ruminant brucellosis in Plateau state, Nigeria. Culling of affected small ruminants and maintenance of good hygienic practices will be useful methods of control at this point in time.[...] Read More.

Keywords: Sero-epidemiology, brucellosis, small ruminants, Plateau State.

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