Short communication: Screening of native and foreign Bradyrhizobium japonicum strains for high N2 fixation in soybean

Four local rhizobia isolates selected after two screening experiments and five USDA Bradyrhizobium japonicum strains were estimated for N₂ fixation in soybean using the ¹⁵N isotope dilution technique. Strain USDA 110 was superior to the local isolates in nodulation and N₂ fixation when inoculated onto soybean cv TGX 1497-ID in a Nigerian soil and could therefore be used as an inoculant for enhanced N₂ fixation in soybean in Nigeria.     

Prevalence of nitrous oxide reducing capacity in denitrifiers from a variety of habitats

Summary A total of 81 strains isolated by T. N. Gamble from soils from eight countries, fresh water lake sediments and nitrified poultry manure were examined for their ability to grow on N₂O as their electron acceptor, as well as for their tendency to produce N₂O from NO ₃ ⁻ in the absence and presence of acetylene. Seventy-seven of the 81 strains were confirmed as denitrifiers. Fifty-nine of the 77 strains grew on N₂O, while 12 strains produced N₂O but could not utilize it. Six strains reduced NO ₃ ⁻ to N₂ but could not grow on N₂O, suggesting that even if N₂O is always an intermediate product of denitrification, it is not always a freely diffusible intermediate. The organisms, however, would consume N₂O that accumulated early in growth and accumulated N₂O in the presence of acetylene. Thus the total number of N₂O users was 65 strains or 83% of the total tested. This implies that the N₂O reducing capacity of denitrifiers occur widely in nature. A high proportion ofPseudomonas fluorescens biotype II reduced N₂O. The accumulation of N₂O from NO ₃ ⁻ in the presence of acetylene provides strong evidence that N₂O is generally an intermediate in denitrification as well as provides additional support for the usefulness of this chemical as a general inhibitor of N₂O reduction.     

Influence of species, sex and drug pretreatment on the metabolism of metyrapone

The metabolism of metyrapone was investigated in three mammalian and four non-mammalian species, and keto reduction was found to be the major metabolic route (except in the cat). Toad, lizard and tortoise did not form metyrapone N-oxides. Rat and cat formed both isomeric N-oxides of metyrapone, whereas rabbit and pigeon have a limited capacity to form only the N-oxide II and N-oxide I, respectively. There were marked sex differences in both keto reduction and N-oxidation in the rat. Anthracene did not affect metyrapone N-oxides formation in the male rat; however phenobarbitone and pregnenolone significantly induced N-oxide II formation, whereas ethanol induced both isomeric N-oxides formation. Cimetidine, a known cytochrome P-450 inhibitor, inhibited the N-oxide II formation but with an enhanced N-oxide I formation.     

Growth yield of denitrifiers using nitrous oxide as a terminal electron acceptor

The molar yields (g cell/mol) forAlcaligenes faecalis, Pseudomonas stutzeri, Paracoccus denitrificans andPseudomonas perfectomarinus batch cultures, under nitrous oxide (N₂O) as the electron acceptor, were 11.2, 8.2, 6.1 and 4.4, respectively.Paracoccus denitrificans andPseudomonas perfectomarinus, which had the slowest growth rates, gave the lowest yields. Large maintenance energy costs may be partially responsible for this. The growth efficiencies ofA. faecalis andPs. perfectomarinus on N₂O indicate that the numbers of sites for oxidative phosphorylation in the electron transport system associated with N₂O reduction are about 49% and 39% of those in the electron transport system associated with O₂ respiration, respectively.     

Bacteriocin-mediated inhibition of Clostridium botulinum spores by lactic acid bacteria at refrigeration and abuse temperatures.

The bacteriocinogenicity of Lactococcus lactis ATCC 11454, Pediococcus pentosaceus ATCC 43200, P. pentosaceus ATCC 43201, Lactobacillus plantarum BN, L. plantarum LB592, L. plantarum LB75, and Lactobacillus acidophilus N2 against Clostridium botulinum spores at 4, 10, 15, and 35 degrees C was investigated by modified deferred and simultaneous antagonism methods. All the strains, except L. acidophilus N2, produced inhibition zones on lawns of C. botulinum spores at 30 degrees C. L. plantarum BN, L. lactis ATCC 11454, and P. pentosaceus ATCC 43200 and 43201 were bacteriocinogenic at 4, 10, and 15 degrees C. Supplementation of brain heart infusion agar with 0 to 5% NaCl increased the radii of inhibition zones during simultaneous antagonism assays. Detectable bacteriocin activities were extracted from freeze-thawed agar cultures of L. plantarum BN and L. lactis ATCC 11454 which had been grown at 4 and 10 degrees C. These results suggest that low levels of L. plantarum BN or L. lactis ATCC 11454, in the presence of 3 or 4% NaCl, could be formulated into minimally processed refrigerated food products for protection against possible botulism hazards.     

Nodulation and biological nitrogen fixation of 80 soybean cultivars in symbiosis with indigenous rhizobia

Eighty soybean cultivars were assessed for their potential for nodulation and nitrogen fixation with indigenous rhizobia in a Nigerian soil. Seventy-six days after planting (DAP) 87%, 3% and 10% of the soybean cultivars had from 0 to 30, 31 to 60 and over 61 nodules/plant, respectively. Only 8% had a nodule dry weight of 600 to 1100 mg/plant. At 84 DAP the proportion of nitrogen derived from the atmosphere (Ndfa) ranged from 0 to 65% 16% of the cultivars derived 51 to 65% of their N₂ from the atmosphere. The diversity of soybean germplasm and the variation in nodulation and N₂ fixation permitted the selection of the five best cultivars in terms of their compatibility with indigenous rhizobia, % Ndfa and the amount of N₂ which they fixed.     

Crop storage losses in southern Nigeria caused by the activities of micro-organisms

Summary In the southern part of Nigeria, maize, cassava, and yam are the major food crops grown, and they constitute an important source of carbohydrate in the diet of the inhabitants of the area. There are various traditional methods for storage of these crops and all have been shown to lead to storage losses both quantitatively and qualitatively. Micro-organism, especially the fungi, are important as agents of deterioration and spoilage of these crops during storage. Factors that influence the infestation and growth of micro-organisms in these crops during storage are many with moisture being especially significant. To aid in their preservation, cassava and yams are usually processed into more shelf-stable products such as garri and fufu from cassava as well as yam chips and fluor from yam. All these processed products, in spite of their relatively shelf-stable nature, are still subject to microbial infection if improperly handled and stored. It is concluded that much work needs to be done in Nigeria to improve storage conditions.

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Résumé Dans le Sud du Nigéria, le maïs, le manioc et la patate douce sont les récoltes alimentaires majeures, et celles-ci constituent une source importante d'hydrates de carbone dans l'alimentation des habitants locaux. Il y a plusieurs méthodes traditionnelles pour le stockage de ces récoltes et toutes ont révélé conduire à des pertes tant quantitatives que qualitatives par stockage. Les microorganismes, particulièrement les moisissures, sont d'importants agents de détérioration et d'avarie de ces récoltes pendant le stockage. De nombreux facteurs influencent l'infection par et la croissance des microorganismes dans ces récoltes durant le stockage, particulièrement l'humidité. Pour améliorer leur conservation, le manioc et la patate douce sont en général transformées en produits stables à conserver en rayonnage comme le garri et le fufu de manioc ou encore les chips et la farine de patate douce. Tous ces produits transformés, malgré leur aptitude à la conservation en rayannage, sont néanmoins sujets à l'infection microbienne lorsqu'ils sont manipulés et conservés de manière impropre. Il faut en conclure que beaucoup de travail reste à faire au Nigéria pour améliorer les conditions de stockage.El maíz, la mandioca y el ñame son los cultivos, destinados a la alimentación, más importantes del sur de Nigeria, constituyendo la principal fuente de carbohidratos para los habitantes del area. Todos los métodos de almacenamiento tradicionales de estos cultivos producen perdidas tanto cuantitativas como cualitativas. Los microorganismos, especialmente los hongos, son agentes importantes de este deterioro. Son muchos los factores que influyen en la infestación y crecimiento de los microorganismos durante el almacenamiento de dichas cosechas, siendo la húmedad especialmente importante. Para mejorar su conservación la mandioca y el ñame se transforman en productos más estables tales como fufu y garri en el caso de la mandioca, y harina y rodajas cocinadas (chips) en del ñame. Todos estos productos transformados, a pesar de su naturaleza relativamente estable, están todavía sujetos a infección microbiana si se manipulan o almacenan de forma inadecuada. Se concluye que restan por hacer muchos trabajos para poder mejorar las condiciones de almacenamiento en Nigeria.

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Paper based on a presentation made at the VII International Conference on the Global Impacts of Applied Microbiology, Helsinki, 12–16.8.1985.     

Alcohol consumption at midlife and successful ageing in women: a prospective cohort analysis in the nurses' health study

Background

Observational studies have documented inverse associations between moderate alcohol consumption and risk of premature death. It is largely unknown whether moderate alcohol intake is also associated with overall health and well-being among populations who have survived to older age. In this study, we prospectively examined alcohol use assessed at midlife in relation to successful ageing in a cohort of US women.

Methods and Findings

Alcohol consumption at midlife was assessed using a validated food frequency questionnaire. Subsequently, successful ageing was defined in 13,894 Nurses'' Health Study participants who survived to age 70 or older, and whose health status was continuously updated. “Successful ageing” was considered as being free of 11 major chronic diseases and having no major cognitive impairment, physical impairment, or mental health limitations. Analyses were restricted to the 98.1% of participants who were not heavier drinkers (>45 g/d) at midlife. Of all eligible study participants, 1,491 (10.7%) achieved successful ageing. After multivariable adjustment of potential confounders, light-to-moderate alcohol consumption at midlife was associated with modestly increased odds of successful ageing. The odds ratios (95% confidence interval) were 1.0 (referent) for nondrinkers, 1.11 (0.96–1.29) for ≤5.0 g/d, 1.19 (1.01–1.40) for 5.1–15.0 g/d, 1.28 (1.03–1.58) for 15.1–30.0 g/d, and 1.24 (0.87–1.76) for 30.1–45.0 g/d. Meanwhile, independent of total alcohol intake, participants who drank alcohol at regular patterns throughout the week, rather than on a single occasion, had somewhat better odds of successful ageing; for example, the odds ratios (95% confidence interval) were 1.29 (1.01–1.64) and 1.47 (1.14–1.90) for those drinking 3–4 days and 5–7 days per week in comparison with nondrinkers, respectively, whereas the odds ratio was 1.10 (0.94–1.30) for those drinking only 1–2 days per week.

Conclusions

These data suggest that regular, moderate consumption of alcohol at midlife may be related to a modest increase in overall health status among women who survive to older ages. Please see later in the article for the Editors'' Summary     

Kinetics of Iron Oxidation by Thiobacillus ferrooxidans

A statistical relationship between the rate of ferric ion production by a strain of Thiobacillus ferrooxidans and various levels of cell concentration, Fe²⁺ concentration, Na⁺ concentration, and temperature was studied by a direct colorimetric method at 304 nm. The relationship was linear (90 to 93%), cross-product (3 to 4%), and quadratic (1 to 2%). The levels of cell concentration and Fe²⁺ concentration and their respective interactions with one another and the other factors had the most significant effects on the regression models. The solution of the quadratic response surface for optimum oxidation was a saddle point, and the predicted critical levels of temperature, cell concentration, Fe²⁺ concentration, and Na⁺ concentration ranged between −6 and 2°C, 0.43 and 0.62 mg/ml, 72 and 233 mM, and 29.6 mM, respectively.     

Benefits of using magnesium sulphate (MgSO4) for eclampsia management and maternal mortality reduction: lessons from Kano State in northern Nigeria

ABSTRACT: BACKGROUND: Despite clear emphasis through the Millennium Development Goals, the problem of high maternal mortality persists especially within low and middle income countries. Various studies report remarkably high maternal mortality rates in northern Nigeria, where maternal mortality rates exceed 1,000 deaths per 100,000 live births and eclampsia contributes approximately 40% of maternal deaths. Across Nigeria, diazepam is routinely used for the management of eclampsia. Prior to February 2008, diazepam was widely used for the management of eclampsia in Kano state (within northern Nigeria) with case fatality rate being over 20%. While magnesium sulphate (MgSO4) is recognized as the most effective drug for the management of eclampsia; this study aims to compare MgSO4 therapy with diazepam therapy in terms of case fatality rates and costs. FINDINGS: This retrospective study, including 1045 patients with eclampsia and pre-eclampsia during the years 2008 and 2009, reports a drop in case fatality rates from 20.9% (95% CI: 18.7, 23.2) to 2.3% (95% CI: 1.4, 3.2) among eclampsia patients following the MgSO4 intervention. The study observed no significant difference in the cost of using MgSO4 therapy compared to diazepam therapy. CONCLUSIONS: The study found a remarkable reduction in case fatality rate due to eclampsia in those who received MgSO4 therapy with minimal increase in costs when compared to diazepam therapy. Concerted efforts should be focused on properly introducing MgSO4 into emergency obstetric protocols especially within developing countries to reduce maternal mortality and also impact on health system performance.