Microbial diversity and biochemical characteristics of Borassus akeassii wine

Palm wine produced traditionally and consumed by many people in the South-West of Burkina Faso is subject to alteration. In this study, we carried out a follow-up of two palm wines' fermentation during the 10 days in which palm wines are classically produced and consumed. We monitored biochemical characteristics of fermenting wines as well as followed the microflora kinetics using culture-dependent and culture-independent methods. The analysis of the acid content and the bacterial population revealed the correlation between the development of Lactic acid bacteria, acetic acid, and total acidity. Ribosomal intergenic spacer analysis and sequencing results revealed different yeast and bacterial populations for the two palm wines. Although Saccharomyces cerevisiae remained the sole yeast species in one fermentation, it was quickly replaced by Clavispora lusitaniae in the second fermentation, which had never been described until now in palm wine. When considering bacteria, the species Corynebacterium sp., Lactobacillus casei, Lactobacillus paracasei and Leuconostoc sp. were detected in both palm wines. But we also detected Acetobacter pasteurianus, Bacillus cereus and Bacillus thuringiensis in the second fermentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results highlight the evolution of palm wine during the 10 days separating palm tapping and consumption of the fermented wine. The fermentation step is performed within few hours and completed after 24 h. The next days, its acidity increases progressively with the production of lactic and acetic acids by bacteria. The high production of acetic acid is very likely one of the main cause of palm wine degradation during this period. This indicates that the solution to palm wine preservation might be protection against oxygen, as well as the limit of bacterial growth through the use of preservatives.

In vitro anti Mycobacterium tuberculosis H37Rv activity of Lannea acida A. Rich from Burkina Faso

The cytotoxic and anti-Mycobacterium tuberculosis H37Rv activities of hydro-alcoholic extract of Lannea acida A. Rich (Anacardiaceae) were assessed. The cytoxicity evaluation was carried out on THP1 monocytoid cell line (after 24 h at 1; 5 and 10 microg mL(-1)) and showed only a slight modification of lactate dehydrogenase (LDH) release. The rate of monocytes in different stages of mitosis had been amended in absence and presence of extract as follows: Go/G1 58.83-59.83%; synthesis 21.95-18.64%; mitosis 16.67-15.77%; necrosis 2.65-5.64%. The percentage of inhibition of Mycobacterium tuberculosis proliferation was respectively 77.6 and 36.8% at 1.2 and 0.6 mg mL(-1) of extract. This is an interesting experimental study on antimicrobial and immune-stimulating properties of Lannea acida ethanol-water (70% v/v) extract which may contain potential antibacterial and immune-stimulating agents for clinical use.

Mycobacterium tuberculosis drug-resistance in previously treated patients in Ouagadougou, Burkina Faso

BACKGROUND

Tuberculosis drug-resistance becomes common in sub-Saharan Africa; however, very few data are available in Burkina Faso. The aim of this study is to assess the acquired resistance of Mycobacterium tuberculosis complex strains identified in TB patients to four first-line drugs in Ouagadougou.

METHODS

One hundred and ten (110) pulmonary tuberculosis patients with acid-fast bacilli-positive sputum and in situation of failure, relapse, or treatment abandonment were included in the study. Ninety six strains, including 92 (95.8%) M. tuberculosis and 4 (4.2%) M. africanum, were isolated from the sputum samples of these patients. Their drug susceptibility testing was performed using the proportion method. The first-line drugs tested were isoniazid (INH), streptomycin (STR), ethambutol (EMB), and rifampicin (RIF).

RESULTS

The overall drug-resistance rate of M. tuberculosis was 67.4% (n=60), including 3.4% to one drug, 18% to two, 10.1% to three, and 35.9% to four drugs. The resistance to INH, RIF, EMB, and STR were 67.4%, 51.7%, 50.6%, and 44.9%, respectively. Two strains of M. africanum were resistant to all drugs. Forty-six (51.7%) strains were multidrug-resistant (resistant to at least INH and RIF).

CONCLUSIONS

In previously treated patients, the level of resistance of M. tuberculosis complex to commonly used anti-tuberculosis drugs is very high in Ouagadougou. Our results showed that multidrug-resistant tuberculosis could be a public health problem in Burkina Faso.

Energetics of Growth of a Defined Mixed Culture of Desulfovibrio vulgaris and Methanosarcina barkeri: Interspecies Hydrogen Transfer in Batch and Continuous Cultures

Interspecies hydrogen transfer was studied in Desulfovibrio vulgaris-Methanosarcina barkeri mixed cultures. Experiments were performed under batch and continuous growth culture conditions. Lactate or pyruvate was used as an energy source. In batch culture and after 30 days of simultaneous incubation, these organisms were found to yield 1.5 mol of methane and 1.5 mol of carbon dioxide per mol of lactate fermented. When M. barkeri served as the hydrogen acceptor, growth yields of D. vulgaris were higher compared with those obtained on pyruvate without any electron acceptor other than protons. In continuous culture, all of the carbon derived from the oxidation of lactate was recovered as methane and carbon dioxide, provided the dilution rate was minimal. Increasing the dilution rate induced a gradual accumulation of acetate, causing acetate metabolism to cease at above mu = 0.05 h. Under these conditions all of the methane produced originated from carbon dioxide. The growth yields of D. vulgaris were measured when sulfate or M. barkeri was the electron acceptor. Two key observations resulted from the present study. First, although sulfate was substituted by M. barkeri, metabolism of D. vulgaris was only slightly modified. The coculture-fermented lactate produced equimolar quantities of carbon dioxide and methane. Second, acetogenesis and methane formation from acetate were completely separable.

Isolation of a tannic acid-degrading Streptococcus sp. from an anaerobic shea cake digester

An anaerobic digester fed with shea cake rich in tannins and phenolic compounds rich-shea cake and previously inoculated with anaerobic sludge from the pit of a slaughterhouse, enabled six months acclimatization of the bacteria to aromatic compounds. Afterwards, digester waste water samples were subject to successive culture on media with 1 g L(-1) tannic acid allowing the isolation of a bacterial strain coded AB. Strain AB was facultatively anaerobic, mesophilic, non-motile, non-sporulating, catalase and oxidase negative bacterium, namely strain AB, was isolated from an anaerobic digester fed with shea cake rich in tannins and phenolic compounds, after inoculation with anaerobic sludge from the pit of a slaughterhouse and enrichment on tannic acid. The coccoid cells occurred in pair, short or long chains and stained Gram-positive. Strain AB fermented a wide range of carbohydrates including glucose, fructose, galactose, raffinose, arabinose, sucrose, maltose, lactose, starch and cellulose. Optimum growth occurred with glucose and tannic acid at 37 degrees C and pH 8. The pH, temperature and salt concentration for growth ranged from 5 to 9, 20 to 45 degrees C and 0 to 15 g L(-1), respectively. Strain AB converted tannic acid to gallic acid. These features were similar to those of the Streptococcus genus. The determination of tannic acid hydrolysis end products, ability to utilize various organic acids, alcohols and peptides, GC% of the DNA, the sequencing of 16S rRNA gene and DNA-DNA hybridization will permit to confirm this affiliation and to determine the species.

In vitro antiplasmodial and antibacterial activities of Canthium multiflorum Schum and Thonn (Rubiacea) extracts

Because of the resistance of pathogens to actually available drugs, there is a continuous need for new agents to cure several diseases such as malaria and microbial infections. In the establishment of new drugs, plant are often a source of new leads, indeed aqueous, acetone and methanol extracts of Canthium multiflorum were tested for antiplasmodial and antibacterial activities. The antiplasmodial activity was performed on fresh clinical strains of Plasmodium falciparum using light microscopy. The results revealed that the methanol extract was the most active with IC50 of 4.69 microg mL(-1). The NCCLS microdilution method performed on clinical and reference strains of pathogenic bacteria yielded MIC and MBC values ranging from 312 to 1250 and 625 to 2500 microg mL(-1), respectively. The qualitative analysis of the extract revealed the presence of several chemical groups such as alkaloids, terpens and tannins that might be responsible for the activity of the plant. The issue of this study showed that C. multiflorum is a plant that many attention should be paid to because of it pharmacological potentials.

[Hygienic quality of meat used in institutional food services: university cafeterias in Ouagadougou (Burkina Faso)]

This present study was conducted to assess the hygienic quality of meals served in three cafeterias at the national university in Ouagadougou and the compliance of kitchen staff with good hygiene practices. Microbiological analyses assessed the hygienic quality of the raw meat and of meat-based meals. The results showed poor hygiene practices by food handlers along the food chain. These observations were confirmed by the identification of salmonella, coliform and staphylococcal bacteria in raw meat and cooked meals. Overall, 60% of the raw meat samples were unsatisfactory for aerobic mesophilic flora and 6.6% for salmonella. For the cooked meat meals, on the other hand, 45% of the samples were satisfactory for aerobic mesophilic flora, 100% for salmonella, 93.3% for fecal thermotolerant coliforms and 96.6% for staphylococci. These results showed poor hygiene in the handling of raw meat, but a clear improvement in hygienic quality after cooking. Raising the awareness of cafeteria staff about compliance with hygiene rules appears primordial. Moreover improvement of the food environment, the kitchen equipment, and organization as well as the introduction of a cleaning-disinfection programme would make it possible to provide more hygienic meals in these institutional facilities.

Comparative study of leaf and stem bark extracts of Parkia biglobosa against enterobacteria

Hydroethanolic and aqueous extracts of leaf and stem bark of Parkia biglobosa (Jacq) Benth. (Mimosaceae) were tested against clinical isolates Escherichia coli, Salmonella typhi, Shigella dysenteriae and Enterococcus faecalis, and corresponding collection strains E. coli CIP 105 182, Salmonella enterica CIP 105 150, Shigella dysenteriae CIP 54-51 and Enterococcus faecalis CIP 103 907. Discs of Gentamicin, a broad spectrum antibiotic were used as positive controls. The results showed that all the extracts possess antimicrobial activities. A comparative study of the antibacterial activity of the leaves and that of the bark showed that for all the tested microorganisms, the hydroalcoholic extract of the bark is more active than the aqueous extract of the leaf. The hydroethanolic extract of the leaves is as effective as the aqueous extract of the stem bark prescribed by the traditional healer, suggesting it is possible to use leaves other than the roots and bark. The phytochemical screening showed that sterols and triterpenes, saponosides, tannins, reducing compounds, coumarins, anthocyanosides, flavonosides are present in both bark and leaf but in different concentrations.

Antimicrobial effects of the stem bark extracts of Parkia biglobosa (Jacq.) Benth. on Shigellae

Total and hydroalcoholic extracts of the stem barks of Parkia biglobosa (Jacq) Benth. (Mimosaceae) were tested on strains belonging to three species of Shigellae: S. dysenteriae, S. flexneri and S. boydii collected from hospitals in Ouagadougou, Burkina Faso. The results showed that both extracts were active against Shigellae. The hydroalcoholic extract was more active than the decoction (aqueous one) prescribed by the traditional healer. Both extracts were particularly effective against S. dysenteriae, the most virulent of the three pathogenic species. The effects of the extracts have been compared to that of gentamicin. The phytochemical screening on the extracts revealed the presence of sterols, triterpenes, polyphenolic compounds including tannins, flavonoids, coumarins, anthocyanidins. Other components are saponosides and reducing sugars.

Antiplasmodial activity of alkaloid extracts from Pavetta crassipes (K. Schum) and Acanthospermum hispidum (DC), two plants used in traditional medicine in Burkina Faso

In the course of the search for new antimalarial compounds, a study of plants traditionally used against malaria in Burkina Faso was made. An ethnobotanical study permitted the identification of plants currently used by the traditional healers and herbalists. Two plants among them were selected for further study: Pavetta crassipes (K. Schum) and Acanthospermum hispidum (DC). Alkaloid extracts of these plants were tested in vitro against two reference clones of Plasmodium falciparum: the W2 chloroquine-resistant and the D6 chloroquine-sensitive strains. Significant inhibitory activity was observed with Pavetta crassipes (IC(50)=1.23 microg/ml) and A. hispidum (IC(50)=5.02 microg/ml). Antiplasmodial activity was also evaluated against six Plasmodium falciparum isolates from children between 4 and 10 years old. The IC(50) values for the alkaloid extracts were in the range 25-670 ng/ml. These results indicated that P. falciparum wild strains were more sensitive to the alkaloid extracts than strains maintained in continuous culture. Moreover, the alkaloid extracts exhibit good in vitro antimalarial activity and weak cytotoxicity against three human cell lines (THP1, normal melanocytes, HTB-66). Isolation and structural determination are now necessary in order to precisely determine the active compounds.

Ethnobotanical survey and in vitro antiplasmodial activity of plants used in traditional medicine in Burkina Faso

In Burkina Faso, most people in particular, in rural areas, use traditional medicine and medicinal plants to treat usual diseases. In the course of new antimalarial compounds, an ethnobotanical survey has been conducted in different regions. Seven plants, often cited by traditional practitioners and not chemically investigated, have been selected for an antiplasmodial screening: Pavetta crassipes (K. Schum), Acanthospermum hispidum (DC), Terminalia macroptera (Guill. et Perr), Cassia siamea (Lam), Ficus sycomorus (L), Fadogia agrestis (Schweinf. Ex Hiern) and Crossopteryx febrifuga (AFZ. Ex G. Don) Benth. Basic, chloroform, methanol, water-methanol and aqueous crude extracts have been prepared and tested on Plasmodium falciparum chloroquine-resistant W2 strain. A significant activity has been observed with alkaloid extract of P. crassipes (IC(50)<4 microg/ml), of A. hispidum, C. febrifuga, and F. agrestis (4<IC(50)<10 microg/ml). The best result is obtained with aqueous extract of T. macroptera with an IC(50)=1 microg/ml. These results confirm the traditional use of these plants.

Degradation of proteins during the fermentation of African locust bean (Parkia biglobosa) by strains of Bacillus subtilis and Bacillus pumilus for production of Soumbala

AIMS

To examine isolates of Bacillus subtilis and B. pumilus predominant in Soumbala for their ability to degrade African locust bean proteins (ALBP).

METHODS AND RESULTS

Agar diffusion test in casein and ALBP agar was used for screening of isolates. The profiles of water-soluble proteins and free amino acids (FAA) during the fermentation of ALBP by the Bacillus isolates were studied by SDS-PAGE and cation exchange chromatography. The profile of soluble proteins changed with the fermentation time and varied depending on the isolate. The quantity of total FAA and essential FAA such as lysine was increased sharply between 24 and 48 h of fermentation and differed among the isolates. Simultaneously, a pH increase was observed. Cysteine, methionine, leucine, isoleucine, tyrosine and phenylalaline appeared during fermentation.

CONCLUSION

The Bacillus isolates studied degraded ALBP leading to a profile of soluble proteins and FAA specific for each isolate.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study contributes to the selection of Bacillus strains to be used as starter cultures for controlled production of Soumbala.

Polysaccharide hydrolases from leaves of Boscia senegalensis: properties of endo-(1-->3)-beta-D-glucanase

The leaves of Boscia senegalensis are traditionally used in West Africa in cereal protection against pathogens, pharmacologic applications, and food processing. Activities of alpha-amylase, beta-amylase, exo-(1-->3, 1-->4)-beta-D-glucanase, and endo-(1-->3)-beta-D-glucanase were detected in these leaves. The endo-(1-->3)-beta-D-glucanase (EC 3.2.1.39) was purified 203-fold with 57% yield. The purified enzyme is a nonglycosylated monomeric protein with a molecular mass of 36 kDa and pI > or = 10.3. Its optimal activity occurred at pH 4.5 and 50 degrees C. Kinetic analysis gave Vmax, kcat, and Km values of 659 U/mg, 395 s(-1), and 0.42 mg/mL, respectively, for laminarin as substrate. The use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry and high-performance liquid chromatography revealed that the enzyme hydrolyzes not only soluble but also insoluble (1-->3)-beta-glucan chains in an endo fashion. This property is unusual for endo-acting (1-->3)-beta-D-glucanase from plants. The involvement of the enzyme in plant defense against pathogenic microorganisms such as fungi is discussed.

Isolation and characterization of Desulfovibrio burkinensis sp. nov. from an African ricefield, and phylogeny of Desulfovibrio alcoholivorans

A sulfate-reducing bacterium, strain HDvT (T = type strain), was isolated from an anoxic ricefield soil. Cells were Gram-negative, non-sporulating curved rods motile by means of a single polar flagellum. Cytochrome c3 and desulfoviridin were present. In the presence of sulfate, glycerol, 1,2- and 1,3-propanediol, dihydroxyacetone, pyruvate, lactate, fumarate, maleate, malate and succinate were incompletely oxidized mainly to acetate. Sulfite, thiosulfate, elemental sulfur, fumarate, maleate and malate were utilized as alternative electron acceptors. In the absence of added electron acceptors, pyruvate, fumarate, maleate, malate and dihydroxyacetone were fermented. The DNA base composition was 67 mol% G + C. The phylogenetic, phenotypic and physiological characteristics of strain HDvT indicate that it is a new species of the genus Desulfovibrio, for which the name Desulfovibrio burkinensis sp. nov. is proposed; the type strain is HDvT (= DSM 6830T). Phylogenetic analysis confirmed that Desulfovibrio alcoholivorans was a distinct species supporting the previously published phenotypic data.

Anaerobic degradation of 1,2-propanediol by a new Desulfovibrio strain and D. alcoholovorans

A sulfate-reducing bacterium, strain HDv, was isolated from the anoxic soil of a ricefield using lactate as electron donor. Cells were gram-negative, motile, nonsporulating curved rods, with single polar flagella. Substrates were incompletely oxidized to acetate and included glycerol, 1,2- and 1,3-propanediol. Sulfate, sulfite, thiosulfate, elemental sulfur, fumarate, maleate, and malate were utilized as electron acceptors. Pyruvate, fumarate, maleate, malate and dihydroxyacetone were fermented. Desulfoviridin and c-type cytochromes were present. The DNA base composition was 66.6 +/- 0.3 mol% G+C. The isolate was identified as a Desulfovibrio sp.; its metabolic properties were somewhat different from those of previously described Desulfovibrio species. Comparative biochemical study of 1,2-propanediol dissimilation by the new isolate and Desulfovibrio alcoholovorans showed that NAD-dependent dehydrogenases play a key role in the catabolism of this substrate. The hypothetical pathways of 1,2-propanediol degradation by Desulfovibrio spp. are presented.

Characterization of the nickel-iron periplasmic hydrogenase from Desulfovibrio fructosovorans

The periplasmic hydrogenase from Desulfovibrio fructosovorans grown on fructose/sulfate medium was purified to homogeneity. It exhibits a molecular mass of 88 kDa and is composed of two different subunits of 60 kDa and 28.5 kDa. The absorption spectrum of the enzyme is characteristic of an iron-sulfur protein and its absorption coefficients at 400 and 280 nm are 50 and 180 mM-1 cm-1, respectively. D. fructosovorans hydrogenase contains 11 +/- 1 iron atoms, 0.9 +/- 0.15 nickel atom and 12 +/- 1 acid-labile sulfur atoms/molecule but does not contain selenium. The amino acid composition of the protein and of its subunits, as well as the N-terminal sequences of the small and large subunits, have been determined. The cysteine residues of the protein are distributed between the large (9 residues) and the small subunits (11 residues). Electron spin resonance (ESR) properties of the enzyme are consistent with the presence of nickel(III), [3Fe-4S] and [4Fe-4S] clusters. The hydrogenase of D. fructosovorans isolated under aerobic conditions required an incubation with hydrogen or other reductants in order to express its full catalytic activity. H2 uptake and H2 evolution activities doubled after a 3-h incubation under reducing conditions. Comparison with the (NiFe) hydrogenase from D. gigas shows great structural similarities between the two proteins. However, there are significant differences between the catalytic properties of the two enzymes which can be related to the respective state of their nickel atom. ESR showed a higher proportion of the Ni-B species (g = 2.33, 2.16, 2.01) which can be related to a more facile conversion to the ready state. The periplasmic location of the enzyme and the presence of hydrogenase activity in other cellular compartments are discussed in relation to the ability of D. fructosovorans to participate actively in interspecies hydrogen transfer.

Energetics of growth of a defined mixed culture of Desulfovibrio vulgaris and Methanosarcina barkeri: maintenance energy coefficient of the sulfate-reducing organism in the absence and presence of its partner

The maintenance energy coefficient of Desulfovibrio vulgaris was studied by using a chemostat, with Methanosarcina barkeri or sulfate as the electron acceptor; lithium lactate or sodium pyruvate served as the electron donor. The experiments showed that the growth energetics of D. vulgaris or M. barkeri were greatly affected by maintenance energy coefficients. When D. vulgaris grew on lactate or pyruvate medium with sulfate, these coefficients reached 4.40 and 2.80 mM g-1 h-1, respectively; on lactate medium in the presence of M. barkeri the same coefficient reached a value of 2.90 mM g-1 h-1. Results also showed that the increase of the value of the maintenance energy coefficient corresponded to a decrease of the biomass produced. D. vulgaris maximal growth yield values calculated by use of the Pirt equation were slightly higher with M. barkeri (maximal growth yield, 10 g/mol) than with sulfate (maximal growth yield, 7.5 g/mol). This finding could be interpreted by reference to the ATP-generating reactions involved in D. vulgaris growth in the presence of sulfate or M. barkeri.

Microcalorimetric studies of the growth of sulfate-reducing bacteria: comparison of the growth parameters of some Desulfovibrio species

We performed a comparative study of the growth energetics of some species of Desulfovibrio by measuring microcalorimetric and molar growth yield values. Lactate and pyruvate were used as energy sources for sulfate reduction. On lactate-sulfate media Desulfovibrio desulfuricans Norway, Desulfovibrio gigas, and Desulfovibrio africanus exhibited molar growth yields of 4.1 +/- 0.6, 3.7 +/- 1.7, and 1.8 +/- 0.1 g/mol, respectively, whereas on pyruvate-sulfate media the molar growth yields were higher (8.5 +/- 0.8, 7.7 +/- 1.6, and 3.5 +/- 0.5 g/mol, respectively). Thus, we found that D. africanus was the least efficient species in converting energy into cell material. The uncoupling of energy in this strain was obvious since its catabolic activities were high compared with those of the two other strains. The enthalpy changes associated with lactate and pyruvate metabolism were -49 +/- 0.7 and -70.2 +/- 6.0 jK/mol, respectively, for D. desulfuricans, -76.6 +/- 1.8 and -91.2 +/- 1.1 kJ/mol, respectively, for D. gigas, and -78.8 +/- 7.2 and -88.0 +/- 6.2 kJ/mol, respectively, for D. africanus. D. gigas and D. africanus produced only acetate, CO2 and hydrogen sulfide as metabolic end products. In addition to these normal end products, D. desulfuricans Norway produced a small amount of butanol. This butanol production was interpreted as reflecting a regulatory system of electron flow during the catabolism of both substrates. Such metabolism was comparable to that reported for D. vulgaris, which lost part of the reducing power of its energy sources through hydrogen evolution.

Microcalorimetric studies of the growth of sulfate-reducing bacteria: energetics of Desulfovibrio vulgaris growth

The metabolism of Desulfovibrio vulgaris Hildenborough grown on medium containing lactate or pyruvate plus a high concentration of sulfate (36 mM) was studied. Molecular growth yields were 6.7 +/- 1.3 and 10.1 +/- 1.7 g/mol for lactate and pyruvate, respectively. Under conditions in which the energy source was the sole growth-limiting factor, we observed the formation of 0.5 mol of hydrogen per mol of lactate and 0.1 mol of hydrogen per mol of pyruvate. The determination of metabolic end products revealed that D. vulgaris produced, in addition to normal end products (acetic acid, carbon dioxide, hydrogen sulfide) and molecular hydrogen, 2 and 5% of ethanol per mol of lactate and pyruvate, respectively. Power-time curves of growth of D. vulgaris on lactate and pyruvate were obtained, by the microcalorimetric Tian-Calvet apparatus. The enthalpies (delta Hmet) associated with the oxidation of these substrates and calculated from growth thermograms were -36.36 +/- 5 and -70.22 +/- 3 kJ/mol of lactate and pyruvate, respectively. These experimental values were in agreement with the homologous values assessed from the theoretical equations of D. vulgaris metabolism of both lactate and pyruvate. The hydrogen production by this sulfate reducer constitutes an efficient regulatory system of electrons, from energy source through the pathway of sulfate reduction. This hydrogen value may thus facilitate interactions between this strain and other environmental microflora, especially metagenic bacteria.