Survival and preservation after freeze-drying process of thermoresistant acetic acid bacteria isolated from tropical products of Subsaharan Africa

Two thermoresistant acetic acid bacteria (TAAB) were previously isolated and selected for a sustainable development of vinegar fermentation in Subsaharan Africa. Their use as a starter culture in vinegar manufactures in such regions could reduce considerably water cooling expenses. For optimising biomass preservation, the effect of 20% w/w mannitol as cryoprotectant on the cells viability after freeze-drying process and during storage was evaluated. Results showed that freeze-dried cells could be conserved at 4 degrees C for at least 6 months without loss of viability. The main reasons were that cryoprotectant tends to lower the water activity (a(w)) and to maintain a temperature of product weaker than that of the glass transition temperature T-g. Furthermore, the heat resistance of freeze-dried cells during storage was all the more increased that strains were cryoprotected. In addition, intrinsically, an increase of saturated fatty acids with the temperature is the essential modification in the lipidome level of membrane cells when the fermentation occured at a temperature of 30 degrees C. Tolerance to heat during storage was significantly enhanced under such mechanisms. (c) 2006 Elsevier Ltd. All rights reserved

A new pilot plant scale acetifier designed for vinegar production in Sub-Saharan Africa

A novel thermotolerant strain Acetobacter senegalensis sp. nov. (CWBI-B418(T)) isolated in Senegal from mango fruit, previously freeze-dried and conserved at 4 degrees C under vacuum packaging was successfully rehydrated into an acetifying medium. It was used as an inoculum culture and then applied into a new pilot plant scale acetifier (300 L) for vinegar production. This latter was specifically designed to produce a high volume and quality of vinegar in Sub-Saharan Africa at fermentation temperature of 35 degrees C. Several semi-continuous cycles of acetic acid fermentations were carried out. The behaviour of substrate and product concentrations, population of bacteria into the reactor was analysed as well as the evolution of acidity, acetification rates and stoichiometric yields. Operation with this novel bioreactor allowed achieving 8% (v/v) of acetic acid concentration at 35 degrees C. (C) 2007 Elsevier Ltd. All rights reserved

Deriving seasonal dynamics in ecosystem properties of semi-arid savanna grasslands from in situ-based hyperspectral reflectance

This paper investigates how hyperspectral reflectance (between 350 and 1800 nm) can be used to infer ecosystem properties for a semi-arid savanna grassland in West Africa using a unique in situ-based multi-angular data set of hemispherical conical reflectance factor (HCRF) measurements. Relationships between seasonal dynamics in hyperspectral HCRF and ecosystem properties (biomass, gross primary productivity (GPP), light use efficiency (LUE), and fraction of photosynthetically active radiation absorbed by vegetation (FAPAR)) were analysed. HCRF data (&rho;) were used to study the relationship between normalised difference spectral indices (NDSIs) and the measured ecosystem properties. Finally, the effects of variable sun sensor viewing geometry on different NDSI wavelength combinations were analysed. The wavelengths with the strongest correlation to seasonal dynamics in ecosystem properties were shortwave infrared (biomass), the peak absorption band for chlorophyll <i>a</i> and <i>b</i> (at 682 nm) (GPP), the oxygen A band at 761 nm used for estimating chlorophyll fluorescence (GPP and LUE), and blue wavelengths (&rho;₄₁₂) (FAPAR). The NDSI with the strongest correlation to (i) biomass combined red-edge HCRF (&rho;₇₀₅) with green HCRF (&rho;₅₈₇), (ii) GPP combined wavelengths at the peak of green reflection (&rho;₅₁₈, &rho;₅₅₆), (iii) LUE combined red (&rho;₆₈₈) with blue HCRF (&rho;₄₃₆), and (iv) FAPAR combined blue (&rho;₃₉₉) and near-infrared (&rho;₁₂₉₅) wavelengths. NDSIs combining near infrared and shortwave infrared were strongly affected by solar zenith angles and sensor viewing geometry, as were many combinations of visible wavelengths. This study provides analyses based upon novel multi-angular hyperspectral data for validation of Earth-observation-based properties of semi-arid ecosystems, as well as insights for designing spectral characteristics of future sensors for ecosystem monitoring

Thermoresistant properties of acetic acids bacteria isolated from tropical products of Sub-Saharan Africa and destined to industrial vinegar

Among 17 strains isolated from over-producing fruits, such as mangos, and cereals, two specific acetic acids bacteria, CWBI-B418 and CWBI-B419, were selected for their ability of growth and acetate production at higher temperatures. They have confirmed as Acetobacter tropicalis and A. pasteurianus, respectively, through phylogenetic study based on the 16S rDNA gene sequence analysis. The nucleotide sequence data of CWBI-B418 and CWBI-B419 strains had been deposited in the GenBank database under the respective accession nos. AY883036 and AY883035. In an other hand, their ability of growth and acetification with those of the wild-type strain A. pasteurianus LMG 1625(T) showed that CWBI-B418 and CWBI-B419 strains developed an optimum of growth without any appreciable lag phase and a high level of acetic acid production at 35 and 38 degrees C, respectively. The ability of growth and acetification of the wild strain was impossible under such conditions. The CWBI-B418 and CWBI-B419 strains exhibited then thermoresistance and acidoresistance property. The measure of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activity (two enzymes membrane-bound involved in acetic fermentation), realized on a range of temperatures from 25 to 40 degrees C, showed an increasing denaturation more marked in the wild type strain. The inactivation constant of the enzymes ADH and ALDH of these strains was indeed much lower than that of the wild strain. By taking into account of all these physiological potentialities, the use of the CWBI-B418 and CWBI-B419 strains in industrial vinegar production in Sub-Saharan Africa would make it possible to reduce in a considerable way the cooling water expenses. (c) 2006 Elsevier Inc. All rights reserved

O conhecimento sobre Aids de homens idosos e adultos jovens: um estudo sobre a percepção desta doença Awareness about Aids among elderly males and young adults: a study of the perception of this disease

O objetivo foi comparar conhecimento de homens idosos ao de adultos jovens sobre Aids, considerando escolaridade. Estudo epidemiológico, descritivo e de corte transversal, em que foram analisadas informações de 30 idosos e 62 adultos jovens sobre conceito, transmissão, prevenção, diagnóstico e tratamento de Aids, investigadas por entrevista estruturada baseada em questionário validado padronizado. Para análise de contingência e de variância, empregaram-se distribuições de frequências e testes de Qui quadrado ou exato de Fisher e teste t de Student ou Mann-Whitney em nível de significância de 0,05. Foram empregados o teste de Mantel-Haenszel, em nível de significância de 0,05, e os Odds Ratio com intervalos de confiança a 95%, para influência da escolaridade. Constataram-se percepção individual de boa saúde maior em jovens (61,3% contra 43,3% dos idosos) e atividade sexual maior em idosos (80% contra 62,9% dos jovens). Apesar disso foi menos frequente idosos afirmarem conhecimento satisfatório sobre Aids (26,7% contra 80,6% dos jovens); história de teste de HIV (13,3% contra 24,2% dos jovens) e ter recebido orientação sobre Aids (36,7% dos idosos e 98,4% dos jovens). Os idosos tinham informação insuficiente sobre HIV/Aids comparados a adultos jovens, reforçando a necessidade de maior atenção à população idosa.<br>The scope was to compare awareness of elderly males and young adults about aids, taking education into consideration. By means of an epidemiological, descriptive and cross-sectional study, the information of 30 elderly males and 62 young adults about the concept, transmission, prevention, diagnosis and treatment of aids was investigated by structured interviews based on a standardized and validated questionnaire. Frequency distribution, Chi-square test or Fisher's exact test, as well as Student's t test or the Mann-Whitney test were used, with a significance level of 0.05 for contingency and variance analysis. The Mantel-Haenszel test with a significance level of 0.05 and Odds Ratio with 95% confidence intervals were used to determine scholarship influence. Individual perception of good health was greater among young adults (61.3% vs 43.3% for elderly) and major sexual activity for elderly males was detected (80% vs 62.9% of young adults). Nevertheless, the elderly males declared adequate knowledge about aids less frequently (26.7% vs 80.6% of young adults); prior HIV test (13.3% vs 24.2% of young adults) and receiving orientation about aids (36.7% vs 98.4% of young adults). Elderly males had insufficient information on HIV/aids, when compared with young adults, highlighting the need to pay closer attention to the elderly population