Degradation of benzyldimethylalkylammonium chloride by Aeromonas hydrophila sp. K

AIMS: The aim of this work was to study the biodegradation of benzyldimethylalkylammonium chloride (BAC) by Aeromonas hydrophila sp. K, an organism isolated from polluted soil and capable of utilizing BAC as sole source of carbon and energy. METHODS AND RESULTS: High performance liquid chromatography and gas chromatography-mass spectrometry (GC-MS) analysis was used to study BAC degradation pathway. It was shown that during BAC biodegradation, formation of benzyldimethylamine, benzylmethylamine, benzylamine, benzaldehyde and benzoic acid occurred. Formation of benzyldimethylamine as the initial metabolite suggested that the cleavage of Calkyl-N bond occurred as the first step of BAC catabolism. Liberation of benzylmethylamine and benzylamine likely resulted from subsequent demethylation reactions, followed by deamination with formation of benzaldehyde. Benzaldehyde was rapidly converted into benzoic acid, which was further degraded. CONCLUSIONS: Aer. hydrophila sp. K is able to degrade BAC. A degradation pathway for BAC and related compounds is proposed. SIGNIFICANCE AND IMPACT OF STUDY: These findings are significant for understanding biodegradation pathways of benzyl-containing quaternary ammonium compounds.     

Amylase production byEscherichia coli immobilized in silicone foam

Summary Silicone foam was investigated as a support for the immobilization ofEscherichia coli EC147, a recombinant strain which produces a thermostable amylase extracellularly. While colonization of the foam was limited in semicontinuous culture, a fivefold increase in amylase production was achieved.     

Genital Yeast Infections

Genital yeast infection was studied in 533 women seen in a department of venereology. Yeasts were recovered in culture from 138 patients (26% of the total). Candida albicans accounted for 112 (81%) of the isolates and Torulopsis glabrata for 22 (16%); other yeasts were uncommon. There was no evidence that the presence of yeasts was related to age. 32% of the women who were taking an oral contraceptive harboured yeasts, compared with 18% of those who were not.The symptoms and signs of the women with yeast infections were compared with those with vaginal trichomoniasis and those with no evidence of genital infection. It seems that a clinical diagnosis of vaginal mycosis cannot be made with accuracy and that positive identification of yeasts is necessary; for this, cultural methods are the most satisfactory.     

Using detergent to enhance detection sensitivity of African trypanosomes in human CSF and blood by loop-mediated isothermal amplification (LAMP)

Background

The loop-mediated isothermal amplification (LAMP) assay, with its advantages of simplicity, rapidity and cost effectiveness, has evolved as one of the most sensitive and specific methods for the detection of a broad range of pathogenic microorganisms including African trypanosomes. While many LAMP-based assays are sufficiently sensitive to detect DNA well below the amount present in a single parasite, the detection limit of the assay is restricted by the number of parasites present in the volume of sample assayed; i.e. 1 per µL or 10³ per mL. We hypothesized that clinical sensitivities that mimic analytical limits based on parasite DNA could be approached or even obtained by simply adding detergent to the samples prior to LAMP assay.

Methodology/Principal Findings

For proof of principle we used two different LAMP assays capable of detecting 0.1 fg genomic DNA (0.001 parasite). The assay was tested on dilution series of intact bloodstream form Trypanosoma brucei rhodesiense in human cerebrospinal fluid (CSF) or blood with or without the addition of the detergent Triton X-100 and 60 min incubation at ambient temperature. With human CSF and in the absence of detergent, the LAMP detection limit for live intact parasites using 1 µL of CSF as the source of template was at best 10³ parasites/mL. Remarkably, detergent enhanced LAMP assay reaches sensitivity about 100 to 1000-fold lower; i.e. 10 to 1 parasite/mL. Similar detergent-mediated increases in LAMP assay analytical sensitivity were also found using DNA extracted from filter paper cards containing blood pretreated with detergent before card spotting or blood samples spotted on detergent pretreated cards.

Conclusions/Significance

This simple procedure for the enhanced detection of live African trypanosomes in biological fluids by LAMP paves the way for the adaptation of LAMP for the economical and sensitive diagnosis of other protozoan parasites and microorganisms that cause diseases that plague the developing world.     

Haloferax sp. D1227, a halophilic Archaeon capable of growth on aromatic compounds

A pink-pigmented halophilic Archaeon, Strain D1227, was isolated from soil contaminated with oil brine and shown to be a member of the genus Haloferax, based on: (1) its hybridization with a 16S rRNA probe universal for the Archaea; (2) its resistance to a broad spectrum of antibiotics that affect Bacteria; (3) its requirement for at least 0.86 M NaCl and 25 mM Mg²⁺ for growth; (4) its possession of C₅₀-carotenoids characteristic of the halophilic Arachaea; (5) the thin layer chromatographic pattern of its polar lipids, which was identical to that of other species of Haloferax; and (6) its pleomorphic cell morphology. However, in contrast to the known species of Archaea, Haloferax strain D1227 was able to use aromatic substrates (e.g., benzoate, cinnamate, and phenylpropanoate) as sole carbon and energy sources for growth. Physiologically similar organisms, such as Haloferax volcanii, Haloferax mediterrani, Haloarcula vallismortis, and Haloarcula hispanica, could not grow on these aromatic substrates. When grown on ¹⁴C-benzoate, strain D1227 mineralized 70% of the substrate and assimilated 19% of the ¹⁴C-label into cell biomass. In addition to growth on aromatic substrates, D1227 was also capable of growth on a variety of carbohydrates and organic acids. Optimum growth of strain D1227 occurred at 45°C in media containing 1.7–2.6 M NaCl and 100 mM Mg²⁺. Under optimum growth conditions, the cell shape varied from that of an oblate spheroid on mineral salts medium alone, to discshaped, irregular or triangular cells on the same medium amended with yeast extract and tryptone. To our knowledge, this is the first unequivocal demonstration of the ability of an Archacon to grow by mineralization of aromatic substrates, and it adds a new dimension to our appreciation of the physiological diversity of this group of prokaryotes.Abbreviations Ha. Haloarcula - Hf. Haloferax     

STR2: a structure to string approach for locating G-box riboswitch shapes in pre-selected genes

Traditional sequence-based search methods such as BLAST and FASTA can be used to identify sequence similarities. Recently, there is a growing interest in performing RNA shape similarity searches inside selected genes to locate RNA structure motifs that are known to possess functionally important roles. For example, in the newly discovered RNA genetic control elements called "riboswitches", the box domain is known to be highly conserved among various bacterial species in both its nucleotide composition and shape. However, in non-bacterial species, shape conservation is likely to become more important than sequence conservation when searching for riboswitch patterns. For this purpose, we present an approach tailored for detecting RNA shape similarities. We extend the Structure to String (ST R2) method that was initially proposed to locate shape similarities in proteins to identify predicted secondary structures of RNAs. The ST R2 for RNAs is a translation of a secondary structure to a string of characters, after which known sequence-based search algorithms with an efficient implementation are being used. We validate that the ST R2 succeeds to locate G-box riboswitches in prokaryotes, as expected. Subsequently we show running examples when attempting to detect G-box riboswitch candidates in eukaryotes.     

The Arrangement and Spacing of Sugarcane Planting Influence Root Distribution and Crop Yield

Change in the planting arrangement can provide roots a different environment that alters access to soil resources, which can subsequently impact the productivity of above ground crop compartments. Therefore, the aim of this study was to assess the sugarcane yield as well as the distribution and biomass accumulation of roots across different spacing configuration treatments, in the absence of the confounding effect of machine traffic between the crop rows, in two areas with contrasting soil conditions. Two experiments were conducted under field conditions, in clayey and sandy soil. The experiments were conducted across two crop seasons and incorporated a randomized block design that tested six planting configurations: CS, conventional spacing (1.50 m); AS, alternated spacing (0.90?×?1.50 m); TS, triple spacing (0.75?×?0.75?×?1.50 m); PP 1.0 m, precision planting (1.0?×?1.0 m); PP 0.75 m, precision planting (0.75?×?0.75 m); and PP 0.50 m, precision planting (0.5?×?0.5 m). Results showed, in clayey soil, higher sugarcane yield for the PP 0.75 m spacing in the two crops evaluated; while, the PP 1.0 m spacing had the higher production in sandy soil, but only during the first ratoon. In relation to the total sugarcane production per unit area, the yield gains from reduced spacing were most evident for the first two crop cycles. The distribution and root biomass accumulation of sugarcane did not explain the above ground productivity in planting configurations.     

Development and preliminary evaluation of a loop-mediated isothermal amplification procedure for sensitive detection of cryptosporidium oocysts in fecal and water samples

A loop-mediated isothermal amplification (LAMP) procedure for the detection of Cryptosporidium in environmental and fecal samples was developed and evaluated. This is the first demonstration of LAMP applied to detection of Cryptosporidium. Due to its specificity and simplicity, the method could become a useful diagnostic tool for epidemiologic studies of Cryptosporidium presence.     

Development and Preliminary Evaluation of a Loop-Mediated Isothermal Amplification Procedure for Sensitive Detection of Cryptosporidium Oocysts in Fecal and Water Samples

A loop-mediated isothermal amplification (LAMP) procedure for the detection of Cryptosporidium in environmental and fecal samples was developed and evaluated. This is the first demonstration of LAMP applied to detection of Cryptosporidium. Due to its specificity and simplicity, the method could become a useful diagnostic tool for epidemiologic studies of Cryptosporidium presence.