Fatty acids of lipid fractions in extracellular polymeric substances of activated sludge flocs.

Phospholipid (PL), glycolipid (GL), and neutral lipid (NL) FA, and the lipopolysaccharide 2- and 3-hydroxy (LPS 2-OH and 3-OH) FA of activated sludges and extracted extracellular polymeric substances (EPS) were determined on samples collected from two wastewater treatment plants. EPS extracted from sludges by means of sonication and cation exchange contained proteins (43.4%), humic-like substances (11.5%), nucleic acids (10.9%), carbohydrates (9.9%), and lipid-bound FA (1.8%). The lipids associated with EPS were composed of GL, PL, NL, and LPS acids in proportions of 61, 21, 16, and 2%, respectively. The profiles of lipid-bound FA in activated sludges and EPS were similar (around 85 separate FA were identified). The FA signatures observed can be attributed to the likely presence of yeasts, fungi, sulfate-reducing bacteria, gram-positive and gram-negative bacteria, and, in lesser quantities, mycobacteria. Comparison of data from the dates of sampling (January and September) showed that there were more unsaturated PLFA in the EPS extracted from the activated sludges sampled in January. This observation could be partly related to microorganism adaptation to temperature variations. The comparison between two wastewater treatment plants showed that the FA profiles were similar, although differences in microbial community structure were also seen. Most of the FA in sludges had an even number of carbons.

Occurrence of nitrifying bacteria and nitrification in Finnish drinking water distribution systems.

Microbiological nitrification process may lead to chemical, microbiological and technical problems in drinking water distribution systems. Nitrification activity is regulated by several physical, and chemical, and operational factors. However, the factors affecting nitrification in the distribution systems in boreal region, having its specific environmental characteristics, are poorly known. We studied the occurrence and activity of nitrifying bacteria in 15 drinking water networks distributing water with very different origin and treatment practices. The waters included chloraminated surface water, chlorinated surface water, and non-disinfected groundwater. The networks were located in eight towns in different parts of Finland. Our results showed that nitrifying bacteria are common in boreal drinking water distribution systems despite their low temperature. Surprisingly high numbers and activities of nitrifiers were detected in pipeline sediment samples. The numbers of ammonia-oxidizing bacteria and their oxidation potentials were highest in chloraminated drinking water delivering networks, whereas the nitrite-oxidizing bacteria were present in the greatest numbers in those networks that used non-disinfected groundwater. The occurrence of nitrifying bacteria in drinking water samples correlated positively with the numbers of heterotrophic bacteria and turbidity, and negatively with the content of total chlorine. Although nitrifying bacteria grew well in drinking water distribution systems, the problems with nitrite accumulation are rare in Finland.

Effect of liner and core materials of plasterboard on microbial growth, spore-induced inflammatory responses, and cytotoxicity in macrophages.

Microorganisms, when grown on wetted plasterboards, can produce bioactive compounds capable of inducing inflammatory and toxic reactions in mammalian cells. The paper liner of plasterboard is commonly regarded as the major substrate for microbial growth. In this study, we cultured Stachybotrys chartarum, Aspergillus versicolor, Penicillium spinulosum, and Streptomyces californicus on liners and cores of plasterboards in order to examine the role of these main plasterboard components on microbial growth and the resulting bioactivity, which was assessed as the ability of microbial spores to induce inflammatory responses and to evoke cytotoxicity in mouse macrophages. The microbes, isolated from mold problem buildings, were grown under saturated humidity conditions on wetted liners and cores of six different plasterboards. The spores were collected, applied to RAW264.7 macrophages at different doses, and evaluated 24 h after exposure for their ability to evoke cytotoxicity and to stimulate production of nitric oxide (NO), tumor necrosis factor alpha (TNFalpha), and interleukin-6 (IL-6). In general, microbial growth was better on the cores than on the liners. All of the studied microbes collected from cores induced a dose-dependent production of TNFalpha in macrophages. The TNFalpha production stimulated by spores of Stachybotrys, Aspergillus, and Streptomyces paralleled their cytotoxicity. Spores of Streptomyces and Aspergillus collected from liners were among the most potent inducers of NO and IL-6. Good growth of Stachybotrys on cores was associated with high cytotoxicity. Penicillium grew only on cores, but it did not induce major inflammatory mediator productions, nor was it significantly cytotoxic. These results indicate that previously reported microbial growth on plasterboards and spore-induced production of important inflammatory mediators and cell death in macrophages is not only due to the paper liner of plasterboard, but the core material also has a crucial role.

Mycobacterium palustre sp. nov., a potentially pathogenic, slowly growing mycobacterium isolated from clinical and veterinary specimens and from Finnish stream waters.

Taxonomic studies were performed on a phenotypically homogeneous group of 13 mycobacteria isolated from clinical, veterinary and stream-water samples. The methods applied included chromatographic analyses of bacterial lipids, biochemical tests and sequencing of the 16S rDNA and the internal transcribed spacer 1 (ITS1) region. Positive results in urease, Tween 80 hydrolysis and pyrazinamidase tests and a negative result in a semi-quantitative catalase test, combined with the ability to grow at 42 degrees C, distinguished this group among the yellow-pigmented, slowly growing mycobacteria. Unique fatty acid and mycolic acid profiles in chromatographic analyses and the results of gene sequencing indicated that the novel isolates represent a previously undescribed species, for which the name Mycobacterium palustre sp. nov. is proposed. The fatty acid profile obtained by GLC was characterized by the presence of several methyl-branched fatty acid markers. The most prominent markers were 2-methyleicosanoic, tetracosanoic and hexacosanoic acids. According to 16S rDNA sequencing, M. palustre is phylogenetically closest to Mycobacterium kubicae, a recently described species. M. palustre gives a false-positive result in a hybridization test with the AccuProbe Mycobacterium avium complex. One of the strains was isolated from a lymph-node biopsy from a child with cervical lymphadenitis. Thus, M. palustre should be listed among potential inducers of paediatric lymphadenitis. The veterinary isolates originated from the lymph nodes of slaughter pigs. The majority of the strains were recovered from natural waters, which highlights the role of the environment as a source of potentially pathogenic mycobacteria. The type strain of M. palustre is strain E846T (= DSM 44572T = ATCC BAA-377T).

Media for cultivation of indoor streptomycetes.

The growth of 10 indoor Streptomyces spp. isolates on nutritionally complex and selective 26 media revealed that the mycelium production had a tendency to increase in order: starch-casein < glycerol-arginine < glucose-tryptone, and NH(4)NO(3) < Na-caseinate-asparagine. Yeast extract increased mycelium biosynthesis, but not always the growth rate. The strains belonging to streptomycetes most common environmental isolates produced visible mycelium in 5 days on all media.

The microbial community structure of drinking water biofilms can be affected by phosphorus availability.

Microbial communities in biofilms grown for 4 and 11 weeks under the flow of drinking water supplemented with 0, 1, 2, and 5 microg of phosphorus liter(-1) and in drinking and warm waters were compared by using phospholipid fatty acids (PLFAs) and lipopolysaccharide 3-hydroxy fatty acids (LPS 3-OH-FAs). Phosphate increased the proportion of PLFAs 16:1 omega 7c and 18:1 omega 7c and affected LPS 3-OH-FAs after 11 weeks of growth, indicating an increase in gram-negative bacteria and changes in their community structure. Differences in community structures between biofilms and drinking and warm waters can be assumed from PLFAs and LPS 3-OH-FAs, concomitantly with adaptive changes in fatty acid chain length, cyclization, and unsaturation.

Characterisation of Streptomyces spp. isolated from water-damaged buildings.

Abstract Saprophytic Streptomyces spp. common in soil and producing biologically active compounds have been related to abnormal microbial growth in buildings where occupants may have health problems. We characterised 11 randomly selected water-damaged building isolates. The 16S rDNA sequence similarity was over 95.4% between strains so that seven, three, and one sequences had greater than 99.8, 99.7 and 99.7% similarity with those of Streptomyces griseus ATCC 10137 (Y15501), Streptomyces albidoflavus DSM 40455(T) (Z76676), and Streptomyces coelicolor A3(2) (Y00411), respectively. Although differences in morphology, pigmentation, fatty acids, biological activity and pH tolerance indicated that strains did not necessarily match with three single phenotypes, they all appeared to belong to two or three branches of Streptomyces spp. most common environmental isolates.