Assessment of Arthrobacter viscosus as reactive medium for forming permeable reactive biobarrier applied to PAHs remediation

Polycyclic aromatic hydrocarbons (PAHs) are significant environmental contaminants as they are present naturally as well as anthropogenically in soil, air and water. In spite of their low solubility, PAHs are spread to the environment, and they are present in surface water, industrial effluent or groundwater. Amongst all remediation technologies for treating groundwater contaminated with PAHs, the use of a permeable reactive biobarrier (PRBB) appears to be the most cost-effective, energy efficient, and environmentally sound approach. In this technology, the microorganisms are used as reactive medium to degrade or stabilize the contaminants. The main limits of this approach are that the microorganisms or consortium used for forming the PRBB should show adequate characteristics. They must be retained in the barrier-forming biofilm, and they should also have degradative ability for the target pollutants. The aim of the present work is to evaluate the viability of Arthrobacter viscosus as bioreactive medium for forming PRBB. Initially, the ability of A. viscosus to remove PAHs, benzo[a]anthracene 100 μM and phenanthrene 100 μM was evaluated operating in a batch bench-scale bioreactor. In both cases, total benzo[a]anthracene and phenanthrene removals were obtained after 7 and 3 days, respectively. Furthermore, the viability of the microorganisms was evaluated in the presence of chromium in a continuous mode. As a final point, the adhesion of A. viscosus to sepiolite forming a bioreactive material to build PRBB was demonstrated. In view of the attained results, it can be concluded that A. viscosus could be a suitable microorganism to form a bioreactive medium for PAHs remediation.This work has been supported by the Spanish Ministry of Economy and Competitiveness and FEDER Funds (Project CTM 2011-25389). Marta Pazos received financial support under the Ramon y Cajal programme and Marta Cobas under the final project master grant "Campus do Mar Knowledge in depth"

Biodegradation kinetics of 4-fluorocinnamic acid by a consortium of Arthrobacter and Ralstonia strains

Arthrobacter sp. strain G1 is able to grow on 4-fluorocinnamic acid (4-FCA) as sole carbon source. The organism converts 4-FCA into 4-fluorobenzoic acid (4-FBA) and utilizes the two-carbon side-chain for growth with some formation of 4-fluoroacetophenone as a dead-end side product. We also have isolated Ralstonia sp. strain H1, an organism that degrades 4-FBA. A consortium of strains G1 and H1 degraded 4-FCA with Monod kinetics during growth in batch and continuous cultures. Specific growth rates of strain G1 and specific degradation rates of 4-FCA were observed to follow substrate inhibition kinetics, which could be modeled using the kinetic models of Haldane–Andrew and Luong–Levenspiel. The mixed culture showed complete mineralization of 4-FCA with quantitative release of fluoride, both in batch and continuous cultures. Steady-state chemostat cultures that were exposed to shock loadings of substrate responded with rapid degradation and returned to steady-state in 10–15 h, indicating that the mixed culture provided a robust system for continuous 4-FCA degradation

Frequencies of Aneuploid Seedlings Obtained from Aneuploid Apple Accessions (Malus × domestica) Pollinated with Diploid ‘Hongro\u27

To estimate the breeding behavior of aneuploid apple (Malus × domestica), twelve crosses were undertaken with twelve aneuploid accessions pollinated with diploid ‘Hongro\u27 apple. A 2x × 2x cross with ‘Hongro\u27 was also carried out as a control experiment for these aneuploid × diploid crosses. The pollinated aneuploid accessions exhibited relatively high fruit set rates. The apple fruit obtained from the pollinated aneuploid accessions contained less seeds per fruit than those from the 2x × 2x cross. The weight of seeds from the fruits of the pollinated aneuploid accessions was not related to the chromosome number of the aneuploid seed parent. Some of the seeds obtained from the pollinated aneuploid accessions failed to grow into seedlings. Metaphase figures of the root tip cells of seedlings derived from the pollinated aneuploid accessions showed that of 155 seedlings examined 115 were diploid, two were triploid and 38 were aneuploid. The chromosome number of the aneuploid seedlings ranged from 35 to 39, except for 48 chromosomes of one seedling. The seedlings with 35 (2n=2x+1) chromosomes appeared with the highest frequency of 15/38 (39.5%). The chromosome number of the aneuploid seedlings approached to the diploid (2n=34) level, or the number of aneuploid seedlings decreased with increase of chromosome numbers from 35 to 39

Antibacterial and immuno-modulatory activity of ethanol extracts from Lespedeza sp. during Helicobacter pylori infections

Chemical therapeutics targeted against H. pylori may lead to host toxicity and pathogen eradication failures. In this study, ethanolic extracts from five Lespedeza sp. plants were shown to inhibit the gastric-pathogen H. pylori and to modulate cytokine production. Disc agar diffusion assays showed that Lespedeza sp. ethanol extracts possess potent anti-H. pylori activity. Among the five plant extracts, the extracts from L. cyrtobotrya demonstrated the highest anti-H. pylori effect. The growth inhibitory effect against H. pylori was initiated after six h of treatment with plant extracts and the effect remained for a continuous period of 48 h. Incubation of the gastric cells infected with H. pylori with 1.25 to 50 mg/mL of sp. plant extracts resulted in a reduction of the production of cytokine IL-8. The plant ethanol extracts generally had little influence on AGS cell viability, indicating their safety for the treatment of bacterial infections. Three active fractions of L. cyrtobotrya also demonstrated similar anti-H. pylori and immuno-modulatory effects. Taken together, these results provide evidence that Lespedeza sp. plant extracts might be potential sources of new host friendly anti-H. pylori agents. © 2010 The Korean Society for Biotechnology and Bioengineering and Springer-Verlag

Rapid selection of polyphenol-rich tea trees (Camellia sinensis L.) employing a colorimetric method

An efficient and rapid colorimetric method was established for the selection of tea tree lines rich in polyphenol from 160 tea tree lines. The efficient selection method was made possible by the adoption of the Folin-Ciocalteu (FC) colorimetric method for qualitative detection of the polyphenols. The polyphenol composition varied widely among the randomly sampled 160 tea tree lines. The tea tree lines were classified into three groups on the basis of color intensity obtained after treatment of tea extracts with FC reagent. The polyphenol content of the three groups was quantified and validated by UV spectrophotometric analysis. Among various tea lines, H-23 tea line exhibited the highest amounts of polyphenol that was 2.89-fold higher than those found in low polyphenol producing tea tree (H-9). Hence FC colorimetric method can become a reliable selection method for easy and rapid selection of tea population rich in polyphenol in a tea tree breeding programme