Ferruginous Microspherules in Bauxite at Maochang, Guizhou Province, China: Products of Microbe-Pyrite Interaction?

The Maochang bauxite in Guizhou Province is one of the important aluminum ore deposits in southwestern China. Ferruginous spherules, measuring about a few microns across, were found in the transitional layer of the deposit. The EDS and XRD results show that the microspherules are composed mostly of iron （hydr）oxide minerals （goethite） with only weak presence of aluminum and silicon. Occasionally, some pyrite micrograins with dissolved surface are found associated with goethite within the spherules. It is thus suggested that microspherules are linked to pyrite oxidization. It is also thought that microbial activities contribute not only to pyrite oxidization, but also to ball-like assemblage of the iron （hydr）oxides. The mechanism of the formation of ferruginous microspherules is also believed to be important in studying geomicrobiology of bauxite.

Improved maize growth in condition controlled by PGPR inoculation on ferruginous soil in central Benin

Abstract The use of microbial technologies in agriculture is rapidly expanding with the discovery of new bacterial strains effective in improving plant growth. In this study, we tested and highlighted the efficacy of PGPR (Plant Growth Promoting Rhizobacteria) alone or in a consortium on maize growth. For this purpose, a greenhouse experiment was carried out in pots containing sterilized ferruginous soil for 30 days. The corn seeds of the EVDT 97 SRT C1 variety were inoculated with bacterial suspensions of concentration 108 UFC/ml. The experimental device was a random block of 16 three-repeat treatments. The incidence of PGPR inoculated strains is assessed on the biomass growth and yield parameters of maize. At the end of the trial, the results showed that inoculation stimulated plant growth and development and resulted in a significant increase in the height, diameter at the collar, leaf surface and dry weight of aerial biomass. 20.15%, 21%, 32.77% and 37.73% respectively compared to controls, especially in corn plants inoculated with B. thurengiensis;B.thurengiensis B.panthethonicus- S.marcescens et Pseudomonas cichorii- Pseudomonas. putida- Pseudomonas syringae. These results show the potential of using these rhizobacteria as biological inoculants to improve maize productivity in Benin.

Applying Rhizobacteria on Maize Cultivation in Northern Benin:Effect on Growth and Yield

The aim of the study was to investigate the effects of five plant growth-promoting rhizobacteria (PGPR) (Bacillus panthothenicus;Pseudomonas Cichorii;Pseudomonas Putida;Pseudomonas syringae and Serratia marcescens) on the growth and yield of maize on a ferruginous soil under field condition. Maize seeds were inoculated with 10 ml of bacterial suspension. Study was conducted in a completely randomized design with fifteen treatments and three replicates. A half-dose of recommended (13, 17, 17 kg?ha?1) NPK was applied 15 days after emergence. The results show that the Serratia marcescens + 50% NPK treatment yielded the best results for height, fresh underground biomass, dry aboveground biomass, dry underground biomass, and grain yield with respective increases of 41.09%, 217.5%, 213.34%, 93.82%, and 39.05% compared to the control. Maximum stem diameter (increases of 49.65%) was recorded in the plants treated with 100% NPK (full dose NPK) while the highest leaf area (466.36 ± 9.57 cm2), obtained on plant treated with Pseudomonas putida + 50% NPK was 32.08% greater than in the non-inoculated control. Our results suggest the use of these rhizobacteria as biological fertilizers for enhancing the growth and maize seed yield in ferruginous soil in the North of Benin.

Influence of Isolated PGPR Rhizobacteria in Central and Northern Benin on Maize Germination and Greenhouse Growth

The objective of the study was to evaluate the effects of nine plant growth-promoting rhizobacteria (PGPR) alone or in combination on maize seed germination and seedling growth under laboratory and greenhouse conditions. The germination and growth tests were carried out in square petri dishes and pots. Maize seeds were inoculated with suspension of 108 CFU/ml of rhizobacteria. The experimental device was a random block of 16 treatments with four repetitions. Germination test results showed that seeds inoculated with PGPR including the control induced good germination in the range of 93.75% to 100%. The vigor index and root length of the seeds treated with Bacillus panthothenicus were significantly improved by 76.64% and 58.86%, respectively, while the maximal lengths of the seedlings were obtained with Pseudomonas cichorii with an increase of 118.95%. In greenhouse experience, data demonstrated that Serratia marcescens better improved the leaf area, height and underground biomass, respectively by 58.83%, 108.43%, and 59.16% as compared to the control. The highest fresh aerial biomass and air dry matter was obtained with plants treated only with Pseudomonas putida. These results show the potential to use such rhizobacteria as biofertilizers to improve maize productivity in Benin.

Preliminary Geophysical Investigation to Delineate the Groundwater Conductive Zones in the Coastal Region of Akwa Ibom State, Southern Nigeria, around the Gulf of Guinea

This paper presents the first work of its kind within the confines of the study area. It unravels the distribution of the layers of conductive sand and their depths of interaction between freshwater from fresh sands and saltwater within the conductive layers in the coastal region of Akwa Ibom State (Nigeria) around the Gulf of Guinea. Vertical electrical sounding (VES) data whose fidelity was achieved by constraining the data by the available nearby logged borehole information during interpretation was the method applied. In the western region of the study area, the ferruginized and saline water layer is found within the depth range of 22 to 75 m deep. In the northern zone, conductive sandy layer is found within 50 to 210 m and in the eastern zone, the saline and ferruginized sandy layer is found within the depth of 88.5 m and above. Generally, the horizontal and vertical cross sections of the subsoil and the flow regime from water table depths have been delineated. With these information, water can be tapped in the area with caution and the flow direction determined can be used as input parameter in detailed contamination study.

Mesoproterozoic biomineralization:Cyanobacterium-like filamentous siderite sheaths~1.4 Ga

Biomineralization was a key development in a wide variety of organisms,yet its history prior to the Ediacaran remains poorly understood.In this paper,we describe~1420-1330 million year old microscopic tubes preserved as siderite(FeCO_(3)).In size and shape these tubes closely resemble cyanobacterial sheaths forming mineralized mats.We consider two competing explanations for their formation.First,the tubes and associated sediment were originally composed of Ca-carbonate that was subsequently replaced by siderite.In this case,siderite mineralization was early,but post-mortem,as in early silicification,and preferentially preserved the more resilient sheath.However,no relict calcite is observed.Second,the Fe-carbonate mineralogy of the tubes and sediment is synsedimentary.In this case,photosynthetic oxygen may have precipitated Fe-oxyhydroxide that was promptly converted to siderite by dissimilatory iron reduction(DIR).Primary siderite mineralization of cyanobacteria has not been described before.Both explanations link photosynthetic processes to preferential sheath mineralization during the life of the cyanobacteria,as observed in present-day calcified cyanobacteria.This process might include CO_(2)-concentrating mechanisms(CCMs)linked to relatively low levels of atmospheric CO_(2),consistent with empirical estimates of mid-Proterozoic CO_(2)levels based on paleosols and weathering rinds.In either case,these cyanobacterium-like fossils preserved in siderite provide an early example of biomineralization and suggest the interactive in-fluences of both metabolic processes and ambient seawater chemistry.