Fermentation profile of Saccharomyces cerevisiae and Candida tropicalis as starter cultures on barley malt medium.

Saccharomyces cerevisiae C8-5 and Candida tropicalis F0-5 isolated from traditional sorghum beer were tested for kinetic parameters on barley malt extract, YPD (863 medium) and for alcohol production. The results showed that C. tropicalis has the highest maximum growth rate and the lowest doubling time. Values were 0.22 and 0.32 h(-1) for maximum growth rate, 3 h 09 min and 2 h 09 min for doubling time respectively on barley malt extract and YPD. On contrary, glucose consumption was the fastest with S. cerevisiae (-0.36 and -0.722 g/l/h respectively on barley malt extract and YPD). When these two yeasts were used as starters in pure culture and co-culture at proportion of 1:1 and 2:1 (cell/cell) for barley malt extract fermentation, we noticed that maltose content increased first from 12.12 g/l to 13.62-16.46 g/l and then decreased. The highest increase was obtained with starter C. tropicalis + S. cerevisiae 2:1. On contrary, glucose content decreased throughout all the fermentation process. For all the starters used, the major part of the ethanol was produced at 16 h of fermentation. Values obtained in the final beers were 11.4, 11.6, 10.4 and 10.9 g/l for fermentation conducted with S. cerevisiae, C. tropicalis, C. tropicalis + S. cerevisiae 1:1 and C. tropicalis + S. cerevisiae 2:1. Cell viability measurement during the fermentation by using flow cytometry revealed that the lowest mean channel fluorescence for FL3 (yeast rate of death) was obtained with C. tropicalis + S. cerevisiae 2:1 after 48 h of fermentation.

Clostridium perfringens and Clostridium difficile in cooked beef sold in Côte d'Ivoire and their antimicrobial susceptibility.

The aim of this study was to evaluate the prevalence of Clostridium difficile and Clostridium perfringens in cooked beef sold in the streets in Côte d'Ivoire and their antimicrobial susceptibility. A total of 395 kidney and flesh samples of cooked beef were collected from vendors at Abidjan and subjected to C. difficile and C. perfringens isolation and identification by using biochemical tests, API 20A system and PCR detection. Subsequently, the antimicrobial susceptibility test was performed for confirmed isolates. Our results showed the prevalence of 12.4% for C. difficile (11.04% in kidney and 13.45% in flesh) and 5.06% for C. perfringens (2.32% in kidney and 7.17% in flesh). Metronidazole and vancomycin remained the most potent antimicrobial agents against C. difficile while metronidazole and penicillin G were the most potent agents against C. perfringens. The resistance rates to tetracycline, doxycycline, chloramphenicol and erythromycin against C. difficile and C. perfringens isolates ranged from 2.05% to 8.16% and from 20% to 50%, respectively. Among all antimicrobial agents tested against C. difficile, percentages of resistance to quinolones ciprofloxacin, norfloxacin and nalidixic acid as well as to gentamicin and cefotaxime were the highest. Eight resistant phenotypes were defined for C. difficile isolates and eleven resistant phenotypes for C. perfringens isolates. Clindamycin/gentamicin/cefotaxime/ciprofloxacin/norfloxacin/nalidixic acid resistance was the most common phenotype for C. difficile (55.10% of isolates) while norfloxacin/nalidixic acid resistance was the most common phenotype for C. perfringens (20% of isolates).

Identification of yeasts during alcoholic fermentation of tchapalo, a traditional sorghum beer from Côte d'Ivoire.

This study investigated the diversity and dynamics of yeasts involved in alcoholic fermentation of a traditional sorghum beer from Côte d'Ivoire, tchapalo. A total of 240 yeast strains were isolated from fermenting sorghum wort inoculated with dry yeast from two geographic regions of Côte d'Ivoire (Abidjan and Bondoukou). Initial molecular identification to the species level was carried out using RFLP of PCR-amplified internal transcribed spacers of rDNA (ITS1-5.8S-ITS2). Ten different profiles were obtained from the restriction of PCR products with the three endonucleases HaeIII, CfoI and HinfI. Sequence analysis of the D1/D2 domain of the 26S rDNA and the ACT1 gene allowed us to assign these groups to six different species: Saccharomyces cerevisiae-like, Candida tropicalis, Pichia kudriavzevii, Pichia kluyveri, Kodamaea ohmeri and Meyerozyma caribbica. The most frequent species associated with tchapalo fermentation was S. cerevisiae-like (87.36%), followed by C. tropicalis (5.45%) and M. caribbica (2.71%). S. cerevisiae-like strains were diploid heterozygotes and exhibited three to four nucleotides divergence from the type strain in the D1/D2 domain and several indels in the more discriminant sequence of the intron of the ACT1 gene. During the process, the yeast species isolated and their frequencies varied according to the geographic origin of the dry yeast. The occurrence of some species was sporadic and only two non-Saccharomyces species were found in the final product.

Purification, kinetic properties and physicochemical characterization of a novel acid phosphatase (AP) from germinating peanut (Arachis hypogaea) seed.

Acid phosphatase activity was detected in peanut (Arachis hypogaea) cotyledons during germination. Four (4) to six (6) days of germination was the meantime corresponding to maximum hydrolytic activity of this enzyme. The understanding of the role of acid phosphatase activity during germination led to purify this enzyme by successive chromatography separations on DEAE-Sepharose CL-6B, Sephacryl S-100 HR and Phenyl-Sepharose HP to apparent homogeneity from germinated peanut cotyledon five days old. This enzyme designated peanut cotyledon acid phosphatase (AP) had native molecular weight of 24 kDa by gel permeation. SDS-PAGE of the purified acid phosphatase resolved a single protein band that migrated to approximately 21.5 kDa. Thus, this acid phosphatase likely functions as a monomer. The enzyme had optimum pH (5.0) and temperature (55 degrees C), and appeared to be stable in the presence of anionic, cationic and non-ionic detergents. Substrate specificity indicated that the purified acid phosphatase hydrolyzed a broad range of phosphorylated substrates. However, natural substrates such as ADP and ATP were the compounds with highest rate of hydrolysis for the enzyme. Moreover, the purified acid phosphatase exhibited phytase activity. These results showed that this enzyme played a peculiar role during germination, notably in reducing the rate of phytic acid, an antinutritional substance contained in peanut seed.

Les tumeurs malignes de l'oeil et ses annexes. Aspects histo-epidemiologiques de 64 cas observes en 10 ans (1994-2003) dans les CHU d'Abidjan

Il s'agit d'une etude retrospective portant sur 64 cas de tumeurs malignes de l'oeil et ses annexes diagnostiques dans les laboratoires d'anatomie pathologique des centres hospitaliers et universitaires (CHu) de Treichville et de Cocody de 1994 a 2003 (10 ans). AU PLAN EPIDEMIOLOGIQUE : Nous avons observe que les tumeurs malignes de l'oeil et ses annexes etaient rares en Cote d'ivoire avec une frequence annuelle de 6;4 cas. L'age variait de 0 a 74 ans avec une moyenne de 18;6 ans. La predominance masculine est significative. Selon le motif de consultation les patients ont ete recus pour : masse ophtalmique (40;63pour cent); exophtalmie (34;38pour cent); leucocorie (14;66pour cent); hemorragie sous conjonctivale (6;25pour cent) et strabisme (4;69pour cent). AU PLAN HISTOLOGIQUE : Nous avons observe six (05) differents types histologiques:-le retinoblastome 48;44pour cent; -le carcinome epidermoide 31;25pour cent; -les lymphomes malins non Hodgkiniens 12;50pour cent; -le melanome malin 4;69pour cent;-la maladie de Bowen 3;13pour cent. AU NIVEAU DE LA CORRELATION HISTO-EPIDEMIOLOGIQUE : L'age et le siege variaient selon le type histologique. - Le retinoblastome; tumeur intraoculaire ne s'exprimait que chez les enfants de 0 a 15 ans. - Le lymphome de Burkitt ne s'observait que chez l'enfant de 0 a 15 ans avec pour localisation preferentielle l'orbite. - Le carcinome epidermoide; le melanome malin; la maladie de Bowen et les autres lymphomes malins non hodgkiniens s'observaient surtout chez le sujet age et n'avaient pas de localisations preferentielles