Biotechnological potential of plant growth-promoting bacteria from the roots and rhizospheres of endemic plants in ironstone vegetation in southeastern Brazil

Microorganisms associated with plants have a great biotechnological potential, but investigations of these microorganisms associated with native plants in peculiar environments has been incipient. The objective of this study was to analyze the plant growth-promoting bacteria potential of cultivable bacteria associated with rare plants from the ferruginous rocky fields of the Brazilian Iron Quadrangle. The roots and rhizospheres of nine endemic plants species and samples of a root found in a lateritiric duricrust (canga) cave were collected, the culturable bacteria isolated and prospected for distinct biotechnological and ecological potentials. Out of the 148 isolates obtained, 8 (5.4%) showed potential to promote plant growth, whereas 4 (2.7%) isolates acted as biocontrol agents against Xanthomonas citri pathotype A (Xac306), reducing the cancrotic lesions by more than 60% when co-inoculated with this phytopathogen in Citrus sinensis plants. Moreover, other 4 (2.7%) isolates were classified as potential bioremediation agents, being able to withstand high concentrations of arsenite (5 mM As³⁺) and arsenate (800 mM As⁵⁺), by removing up to 35% and 15% of this metalloid in solution, respectively. These same four isolates had a positive influence on the growth of both the roots and the aerial parts when inoculated with tomato seeds in the soil contaminated with arsenic. This is the first time that an investigation highlights the potentialities of bacteria associated with rare plants of ferruginous rocky fields as a reservoir of microbiota of biotechnological and ecological interest, highlighting the importance of conservation of this area that is undergoing intense anthropic activity.

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Antimicrobial Activity of Monoketone Curcuminoids Against Cariogenic Bacteria

We evaluated the antimicrobial activity of 25 monoketone curcuminoids (MKCs) against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Curcumin A ( 10 ) displayed promising activity against Streptococcus mutans (MIC = 50 μg/ml) and Streptococcus mitis (MIC = 50 μg/ml) as well as moderate activity against S. sanguinis (MIC = 100 μg/ml), Lactobacillus casei (MIC = 100 μg/ml), and Streptococcus salivarius (MIC = 200 μg/ml). Results indicated higher activity of compound 10 than that of its bis‐β‐diketone analog. Additionally, compounds 3a (1,5‐bis(4‐methylphenyl)pentan‐3‐one) and 7b (1,5‐bis(4‐bromophenyl)pentan‐3‐ol) were moderately active against S. mitis (MIC = 100 μg/ml) and S. salivarus (MIC = 200 μg/ml).     

Inhibition of Endosteal Vascular Niche Remodeling Rescues Hematopoietic Stem Cell Loss in AML

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Combined Human Genome-wide RNAi and Metabolite Analyses Identify IMPDH as a Host-Directed Target against Chlamydia Infection

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A UNIQUELY CALCIFIED BROWN ALGA FROM HAWAII: NEWHOUSIA IMBRICATA GEN. ET SP. NOV. (DICTYOTALES,PHAEOPHYCEAE)1

An encrusting brown alga from subtidal habitats around the island of Oahu (Hawaiian Islands) represents only the second genus of the class Phaeophyceae to form calcium carbonate, which it deposits primarily as both extracellular and intracellular aragonite, admixed with small (3.3%) amounts of calcite. Plants form expanses 15–100+ cm in extent consisting of horizontally aligned imbricating tiers of distromatic blades 1–4 mm in diameter that are separated from one another by cementing layers of extracellular aragonite, the tiers forming stacks of dozens of laminae and anchored to coral substrata by a basement layer that adheres tightly without haptera or rhizoids. The hypodermal layer of each blade consists of lightly pigmented rectilinear cells bearing either one or two smaller deeply pigmented epidermal cells in cross‐sectional profiles and three or four in long‐sectional profiles, the cells of both layers becoming encased in rigid carbonate skeletons laid down in their outer wall matrices. The successive tiers become stacked by either overgrowing marginal proliferations or new blade primordia that arise from the hypodermal layer of surface laminae and initially spread centrifugally by means of continuous marginal meristems. Neither plurilocular nor unilocular reproductive structures are known. The alga is described as the new genus and species Newhousia imbricata Kraft, G.W. Saunders, Abbott et Haroun and is assigned on the basis of small subunit rDNA gene sequence analyses to the order Dictyotales, family Dictyotaceae, within a strongly supported monophyletic clade that includes Distromium, Lobophora, and Zonaria.     

New species, observations, and a list of new records of brown algae (Phaeophyceae) from the Hawaiian Islands

Two new species of brown algae (Phaeophyceae), Padina moffittiana Abbott et Huisman, sp. nov. and Cutleria irregularis Abbott et Huisman, sp. nov., are described from the Hawaiian Islands (between 19°04′N, 155°35′W and 28°25′N, 178°20′W). In addition, the new combination Cutleria canariensis is proposed for Aglaozonia canariensis. New observations are presented on Nereia intricata Yamada, a species described 67 years ago and known only from its type specimen. New records of a further 14 species are given for the Hawaiian Islands. These 17 taxa bring the total number of species of brown algae recorded for the Hawaiian Islands to 55, an increase of 28%. Of the 15 new records, two are recent ‘accidental’ introductions: Dictyota flabellata (Collins) Setchell et Gardner and Sargassum muticum (Yendo) Fensholt from California. Six records are notable because of their great distances from previously known collections: Nereia intricata Yamada from the Ryukyu Is., Japan; Discosporangium mesarthrocarpum (Meneghini) Hauck, from the Adriatic, Mediterranean, warm Atlantic and southern Australia; Distromium flabellatum Womersley, Spatoglossum macrodontum J. Agardh, and Sporochnus moorei Harvey, from Australia; Desmarestia ligulata (Lightfoot) Lamouroux from temperate and colder waters in the Pacific and Atlantic. A comparison with some Japanese species of Padina confirms that Padina japonica Yamada should be subsumed with Padina sanctae‐crucis Børgesen, as proposed earlier.     

Do benthic and planktonic diatoms produce equivalent effects in crustaceans?

Hippolyte inermis Leach 1814 is a benthic shrimp characterized by a peculiar mechanism of sex reversal influenced by diatom foods. In fact, the appearance of primary females in spring is due to an apoptotic early disruption of the androgenic gland and of the male gonad, triggered by still unknown compounds present in diatoms of the genus Cocconeis. The influence of diatoms on the reproductive ecology and life cycle of planktonic crustaceans has been demonstrated previously: some planktonic diatoms produce aldehydes inducing apoptosis in the embryos and in the larvae of marine copepods, reducing their viability. Both benthic and planktonic diatoms therefore produce compounds having an apoptotic effect on some tissues of target crustaceans, although the ecological significance of the two processes is different: deleterious for copepod populations, regulative for shrimps associated with Posidonia oceanica. In the present article we experimentally administered specific planktonic diatoms, their fractions and compounds known to induce apoptosis in planktonic copepods, to H. inermis postlarvae, to check whether the apoptotic effect is due to an identical family of diatom compounds, and to establish whether the processes observed in the plankton and in the benthos, respectively, are analogous or homologous, from an ecological point of view. Our results indicated that diatom compounds acting in the two systems are different, since both planktonic diatoms and their aldehydes had negligible effects on the sex ratios of cultured shrimps.     

Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions.

Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the possible interferences of these sulfur compounds with the BioDeNOx process need to be identified. Therefore, the effect of the sulfur compounds Na2SO4, Na2SO3, and H2S on the biological NO reduction in aqueous solutions of Fe(II)EDTA2- (25 mM, pH 7.2, 55 degrees C) was studied in batch experiments. Sulfate and sulfite were found to not affect the reduction rate of Fe(II)EDTA2- complexed NO under the conditions tested. Sulfide, either dosed externally or formed during the batch incubation out of endogenous sulfur sources or the supplied sulfate or sulfite, influences the production and consumption of the intermediate nitrous oxide (N2O) during Fe(II)EDTA2- bound NO reduction. At low concentrations (0.2 g VSS/l) of denitrifying sludge, 0.2 mM free sulfide completely inhibited the nitrosyl-complex reduction. At higher biomass concentrations (1.3-2.3 g VSS/l), sulfide (from 15 microM to 0.8 mM) induced an incomplete NO denitrification with N2O accumulation. The reduction rates of NO to N2O were enhanced by anaerobic sludge, presumably because it kept FeEDTA in the reduced state.