Biomedical subjects

Marja Tuomela

Publications and source records attributed to Marja Tuomela.

5 recordsLinked to original sources

PubMed2006

Microbial activities in soils of a former sawmill area.

To find out microbial metabolic functioning and toxicity in a former sawmill area, carbon dioxide evolution, methane oxidation potential, 10 hydrolytic enzyme activities, Vibrio fischeri test, fluorescein diacetate hydrolysis activity (FDA), soil pH, carbon, nitrogen and pentachlorophenol (PCP) content were measured at four sites. The area is contaminated with aged chlorophenols. Chlorophenol content of soil was analyzed with a novel HPLC-MS technique, which allowed to measure chlorophenols without derivatization. The sites had a pollution gradient from 0.5 to 15 microg PCP g dw of soil(-1). Endogenous carbon dioxide evolution, methane oxidation potential, butyrate-esterase, acetate-esterase, sulphatase and aminopeptidase activities were lower at the site 2 than 3, although the site 2 and 3 had similar content of carbon and nitrogen. The soil was toxic in V. fischeri test at the site 2, which had high content of PCP (3.93+/-1.00 microg PCP g dw of soil(-1)). The results indicated that endogenous carbon dioxide evolution, methane oxidation potential, butyrate-esterase, acetate-esterase, sulphatase and aminopeptidase activities were sensitive to PCP in the soil. The results indicated that alpha-glucosidase, beta-glucosidase, beta-xylosidase, beta-cellobiosidase, phosphomonoesterase, N-acetyl-glucosaminidase activity and FDA hydrolysis activity were not sensitive to PCP in the soil. Soil processes involved in the cycling of carbon, nitrogen, sulphur and phosphorus were only slightly vulnerable in the former sawmill area and most sensitive microbial species were probably replaced with more tolerant ones to maintain and recover functioning of the former sawmill soils.

Acetylesterase↗

PubMed2006

Enhancement of bioconversion of high-molecular mass polycyclic aromatic hydrocarbons in contaminated non-sterile soil by litter-decomposing fungi.

With the focus on alternative microbes for soil-bioremediation, 18 species of litter-decomposing basidiomycetous fungi were screened for their ability to grow on different lignocellulosic substrates including straw, flax and pine bark as well as to produce ligninolytic enzymes, namely laccase and manganese peroxidase. Following characteristics have been chosen as criteria for the strain selection: (i) the ability to grow at least on one of the mentioned materials, (ii) production of either of the ligninolytic enzymes and (iii) the ability to invade non-sterile soil. As the result, eight species were selected for a bioremediation experiment with an artificially contaminated soil (total polycyclic aromatic hydrocarbon (PAH) concentration 250 mg/kg soil). Up to 70%, 86% and 84% of benzo(a)anthracene, benzo(a)pyrene, and dibenzo(a,h)anthracene, respectively, were removed in presence of fungi while the indigenous microorganisms converted merely up to 29%, 26% and 43% of these compounds in 30 days. Low molecular-mass PAHs studied were easily degraded by soil microbes and only anthracene degradation was enhanced by the fungi as well. The agaric basidiomycetes Stropharia rugosoannulata and Stropharia coronilla were the most efficient PAH degraders among the litter-decomposing species used.

Biodegradation, Environmental↗

PubMed2004

Influence of Pb contamination in boreal forest soil on the growth and ligninolytic activity of litter-decomposing fungi.

Lignin mineralization activity of three basidiomycetous litter-decomposing fungi (LDF) was studied with humus layer samples taken from a boreal forest soil. The total Pb concentration in the samples was 32,000 mg kg(-1) and water soluble Pb 67 mg kg(-1). Synthetic lignin mineralization by Collybia dryophila and Clitocybe (Lepista) nebularis was strongly inhibited, whereas Stropharia coronilla was more tolerant to Pb stress in soil and liquid cultures. Purified laccases maintained their activity and purified MnPs remained partly active up to a concentration of 1450 mg Pb l(-1). High concentrations of Pb inhibited the growth of LDF and affected the activity of ligninolytic enzymes, but the extent of inhibition varied among different LDF species. In consequence, Pb contamination in soil may have a negative impact on recycling of organic carbon.

Analysis of Variance↗

PubMed2004

Modification of humic acids by the compost-dwelling deuteromycete Paecilomyces inflatus.

The soil mold Paecilomyces inflatus is capable of modifying and partially mineralizing synthetic and natural humic acids (HAs) in compost environments. HA degradation studies using a synthetic HA (14C-HA) in autoclaved compost microcosms showed that, after 12 weeks of cultivation, P. inflatus mineralized approximately 5% of the 14C-labeled HA to 14CO2, while 6% of the 14C-HA was converted into 14C-labeled water-soluble fragments (fulvic-acid-like fraction). About 40% was still present as NaOH-soluble HA representing unmodified or only slightly modified humic material (compared with 60% in the controls). Modification of natural HAs extracted from compost was followed by their partial decolorization (30%) in liquid cultures of P. inflatus. Bleaching of the medium was accompanied by moderate changes in the molecular mass distribution of both the HA and fulvic-acid fractions, which were analyzed with high-performance size exclusion chromatography. HA modification was most pronounced during the primary growth phase of the fungus and was associated with increased laccase activity.

Carbon Radioisotopes↗

PubMed2002

Priming effect as determined by adding 14C-glucose to modified controlled composting test.

The development of new biodegradable packaging materials, especially biodegradable plastics, has created a need for biodegradability testing. The European standard for controlled composting test was used in this study for assessing if the addition of a test material results in excess CO2 production in compost. This effect, designated as the priming effect, would give an erroneous result for biodegradation, which is based on CO2 formation from the test material. Glucose was selected as a test substrate because it is the degradation product of starch and cellulose, which are major compounds of many packaging materials. Both 14C-glucose and non-labelled glucose was applied to nine compost samples of variable stability and age from two weeks to 1.5 years. CO2 and 14CO2 evolution were measured during the incubation. Biodegradation of glucose in unstable composts (age <6 months) was negative and 14CO2 evolution was poor, although the respective composts without glucose produced relatively high amounts of CO2. It was concluded that a negative priming effect was observed in unstable composts, in which glucose remained mostly non-degraded and apparently inhibited the mineralization of native organic matter in the compost. In stable composts (age > or = 6 months), biodegradation of glucose was high and approximately equal to 14C-glucose mineralization, i.e., the composts showed no priming effect. Young composts were unsuitable for controlled composting test due to lack of stability. It is important to ensure that the compost inoculum used for the test is sufficiently stable.

Bacteria↗