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See detailAccelerated storage testing of freeze-drying Pseudomonas fluorescens BTP1, BB2 and PI9 strains
Mputu Kanyinda, Jean-Noël ULg

in African Journal of Biotechnology (2012), 11

Freeze-dried cultures of P.fluorescens are used in agriculture and microbiological industry. However, P. fluorescens is very susceptible to damage during freeze-drying and subsequent storage and it would ... [more ▼]

Freeze-dried cultures of P.fluorescens are used in agriculture and microbiological industry. However, P. fluorescens is very susceptible to damage during freeze-drying and subsequent storage and it would be useful to increase culture viability during storage. The viability of freeze-dried P. fluorescens strains (BTP1, PI9 and BB2) was evaluated by using the Arrhenius model. This model was described by measuring of reaction rate constants (D or k) and temperature sensitivity of rate constant (z or Ea). The freeze-dried P.fluorescens strains was stored in glass tubes at 60°C, 37°C and 4°C for 8 h, 28 days and 2 months, respectively. D value decreased or k increased with an increase of the storage temperature. By comparing their decimal reduction time (D), we observed that BB2 strain was more resistant than BTP1 and PI9 at 37 °C and 60 °C. The activation energy of all P. fluorescens strains are not significantly different and thermal inactivation may occur by the same mechanism. Thus it was possible to compare rate constants of survival for the freeze-dried P. fluorescens strains. These results will be useful to the development of improved reference materials and samples held in culture collections. [less ▲]

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See detailAssessment of non-genetic parameters of the racing performances of Arabian and Thoroughbred horses in Algeria
Tennah, Safia ULg; Kafidi, Nacer; Antoine-Moussiaux, Nicolas ULg et al

in African Journal of Biotechnology (2012)

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See detailMicrobiological and physicochemical characteristics of Rwandese traditional beer "ikigage"
Lyumugabe Loshima, François ULg

in African Journal of Biotechnology (2010), 9(27),

Samples of traditional sorghum beer Ikigage was collected in the southern province of Rwanda and analyzed for microbiological and physico-chemical contents. Ikigage contained total aerobic mesophilic ... [more ▼]

Samples of traditional sorghum beer Ikigage was collected in the southern province of Rwanda and analyzed for microbiological and physico-chemical contents. Ikigage contained total aerobic mesophilic bacteria (33.55 x 106 cfu/ml), yeast (10.15 x 106 cfu/ml), lactic acid bacteria (35.35 x 104 cfu/ml), moulds (4.12 x 104 cfu/ml), E. coli (21.90 x 103 cfu/ml), fecal streptococci (22.50 x 103 cfu/ml), Staphylococcus aureus (16.02 x 103 cfu/ml), total coliform (32.30 x 103 cfu/ml), ethanol, soluble protein, reducing sugars, total acidity, pH and Brix were 2.2% (v/v), 9.2 g/l, 2.3, 1.7%, 3.9 and 11.5 bx, respectively. The yeast was identified by API 20 C test and confirmed by PCR-Sequencing of ITS-5.8S region of rDNA. Seventy yeasts isolated in the samples were found to belong to either Saccharomyces cerevisae, Candida inconspicua, Issatchenkia orientalis, Candida magnolia and Candida humilis. Lactic acid bacteria were identified using the API 50 CHL system. Ten different isolates of lactic acid bacteria belonged exclusively to the genus Lactobacillus: Lactobacillus fermentum, Lactobacillus buchneri, and Lactobacillus sp. The micro-organisms of fecal origin are from the water and the operations postfermentation process. The presence of potential pathogens emphasizes the importance of developing starter cultures with GRAS status for commercialization of ikigage. [less ▲]

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See detailChemical properties of 11 date cultivars and their corresponding fibers extracts.
Borchani, C.; Besbes, Souhail; Blecker, Christophe ULg et al

in African Journal of Biotechnology (2010), 9(26), 4096-4105

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See detailMicrobiological and physico-chemical characteristic of Rwandese traditional beer «Ikigage»
Lyumugabe, F.; Kamaliza, C.; Bajyana, E. et al

in African Journal of Biotechnology (2010), 9(27), 4241-4246

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See detailProduction of freeze-dried lactic acid bacteria starter culture for cassava fermentation into gari.
Yao, Amenan Anastasie ULg; Dortu, Carine; Egounlety, Moutairu et al

in African Journal of Biotechnology (2009), 8(19), 4996-5004

Sixteen lactic acid bacteria, eight Lactobacillus plantarum, three L. pentosus, 2 Weissella paramesenteroides, two L. fermemtum and one Leuconostoc mesenteroides ssp. mesenteroides were previously ... [more ▼]

Sixteen lactic acid bacteria, eight Lactobacillus plantarum, three L. pentosus, 2 Weissella paramesenteroides, two L. fermemtum and one Leuconostoc mesenteroides ssp. mesenteroides were previously isolated from cassava fermentation and selected on the basis of their biochemical properties with a view to selecting appropriate starter cultures during cassava fermentation for gari production. In this study, the potential of these pre-selected strains as suitable freeze-dried cultures was evaluated. Their ability to tolerate the freeze-drying process was assessed by dehydration in a glycerol solution of increasing concentration, followed by staining with two fluorescent markers: rhodamine 123 and propydium iodide. Twelve strains that recovered more than 50% of their population value after visualisation on an epi-fluorescent microscope were produced in a bioreactor and freeze-dried. The technological characteristics identified after the freeze-drying process, were a high cell concentration or high survival rate. The ability of the freeze-dried strains to recover their acidification activity was evaluated through the determination of the pH, titratable acidity (% lactic acid/g Dry Weight) and cell count over 24 h on MRS broth. Ultimately, the strains L. plantarum VE36, G2/25, L. fermentum G2/10 and W. paramesenteroides LC11 were selected to be developed as freeze-dried starter cultures for gari production. [less ▲]

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See detailCharacterization of lactic acid bacteria isolated from poultry farms in Senegal
Coulibaly, Ibourahema ULg; Dubois Dauphin, Robin ULg; Destain, Jacqueline ULg et al

in African Journal of Biotechnology (2008), 7(12), 2006-2012

The group that includes the lactic acid bacteria is one of the most diverse groups of bacteria known and these organisms have been characterized extensively by using different techniques. In this study ... [more ▼]

The group that includes the lactic acid bacteria is one of the most diverse groups of bacteria known and these organisms have been characterized extensively by using different techniques. In this study, thirty lactic acid bacterial strains were isolated from soils chicken faeces and feathers. A total of nineteen isolates were obtained and by sequential screening for catalase activity and Gram-staining, eight were determined to be LAB out of which six were established to be homofermentative by the gel plug test. Five isolates were identified by use of the API 50CHL kit and four Lactobacilli strains and one Lactococci strain were selected to study their growth and lactic acid production profiles in a time course experiment. The Lactobacilli strains, both isolated from faeces, produced higher amounts of cells and lactic acid from soils as compared to the lactococci strain isolated from feathers. L (+)-lactic acid is the only optical isomer for use in pharmaceutical and food industries because is only adapted to assimilate this form. The optical isomers of lactic acid were examined by L (+) and D (-) lactate dehydrogenase kit. Lactobacilli strains produced combination of both optical isomers of lactic acid. Among them, Lactobacillus casei subsp. casei produced the low amount of D (-)-lactic (2%). The optimum rates of glucose for lactic acid production by Lactobacillus strains were 180 and 120 g/l for Lactobacillus plantarum and Lactobacillus paraplantarum, respectively. [less ▲]

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See detailMacronutrient composition of three cucurbit species cultivated for seed consumption in Côte d'Ivoire
Loukou, A. L.; Gnakri, D.; Djè, Y. et al

in African Journal of Biotechnology (2007), 6(5), 529-533

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See detailInhibitory activity of lactobacillus curvatus CWBI-B28 against Listeria monocytogenes and ST2-verotoxin producing Escherichia coli O157
Ghalfi, H.; Thonart, Philippe ULg; Benkerroum, N.

in African Journal of Biotechnology (2006), 5(22), 2303-2306

A bacteriocin- producing strain of Lactobacillus curvatus CWBI- B28 isolated from raw meat was shown to inhibit Listeria monocytogenes and pathogenic strains of Escherichia coli by the well diffusion ... [more ▼]

A bacteriocin- producing strain of Lactobacillus curvatus CWBI- B28 isolated from raw meat was shown to inhibit Listeria monocytogenes and pathogenic strains of Escherichia coli by the well diffusion assay. To confirm whether the bacteriocin was involved in E. coli O157 inhibition, growth of the pathogen was monitored in the neutralized cell- free supernatant ( NCFS) pre- treated with pronase E or catalase. Alternatively, E. coli O157 ( VH21) was co- cultured with Lb. curvatus CWBI- B28 in MRS broth. The results of the well- diffusion assay suggested that the inhibition of E. coli O157 ( VH21) was partially due to the bacteriocin; however, growth monitoring indicated that such inhibition is exclusively due to hydrogen peroxide. In pronase- added NCFS ( i. e., absence of bacteriocin) the colony forming units ( cfus) of E. coli O157 ( VHA21) declined to below the detectable limit after 24 h of incubation at 37 C. However, in presence of catalase no inhibition of the pathogen was observed and the cfus increased steadily to reach 8 log units in 24 h. Moreover, in co- culture, a significantly accelerated inhibition of E. coli O157 ( VH21) was observed in MRS broth as compared to the NCFS without added catalase and the cfus decreased to below the detectable limit in 8 h instead of 24 h, respectively. [less ▲]

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See detailOptimization Of Issr Marker For African Edible-Seeded Cucurbitaceae Species' Genetic Diversity Analysis
Dje, Yao; Tahi, G. C.; Zoro Bi, Arsène I. et al

in African Journal of Biotechnology (2006), 5(2), 83-87

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See detailPolyphasic Identification Of A New Thermotolerant Species Of Lactic Acid Bacteria Isolated From Chicken Faeces
Sow, Nm.; Dubois Dauphin, Robin ULg; Weber, Dominique ULg et al

in African Journal of Biotechnology (2005), 4(5),

Two thermotolerant and desiccation tolerant lactic acid bacteria (TDLAB) were pointed out from twenty isolated strains from soils and dried chicken faeces. Samples were collected in poultry farms in the ... [more ▼]

Two thermotolerant and desiccation tolerant lactic acid bacteria (TDLAB) were pointed out from twenty isolated strains from soils and dried chicken faeces. Samples were collected in poultry farms in the vicinity of Dakar, Senegal (West Africa). The two new isolates were called Sp.4 (Sp.4=CWBI-B534=LMG7278) and Sp.20 (Sp.20=CWBI-B545=LMG7279). They are Grampositive, catalase-negative, facultatively anaerobic, non-motile, and non-spore-forming rods. Both produce D/L lactic acid via homofermentative pathway. Growth of the strains occurred between 15°C and 44°C. The optimum temperature for growth was in 30°C-37°C temperature and pH 3-8 range. Desiccation treatment in glycerol showed 30% survival rates. Complex total fatty acid pattern of the strains showed the presence of C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3. SDS-PAGE of total protein of both strains placed them in L. plantarum group. AFLP analysis showed a phylogenetic proximity of the two strains with L. plantarum stricto sensu species. Specific amplified 16s rDNA restriction analysis (ARDRA) of the 16S rDNA gene, however, showed that these thermotolerant strains were not L. plantarum. ITS sequencing revealed that Sp.20 (LMG 7279) could be classed into Lactobacillus paraplantarum species since the short sequence of ITS showed 95% of similarity with reference species. Polyphasic identification shows that Sp.4, (the type strain is LMG 7278T) represent a new species within the genus Lactobacillus with only 88%+/-1 ITS sequence similarity with reference species. For which the name Lactobacillus aminata sp. nov. is proposed. [less ▲]

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