title: Predominance of Gram-positive bacteria in house dust in the low-allergy risk Russian Karelia.
abstract: Simple living conditions and farming environment have been associated with reduced risk for allergic diseases such as atopy and asthma but the factors responsible for this effect remain unresolved. We examined the bacterial composition of house dusts obtained from Finnish and Russian Karelia, two adjacent areas with high and low occurrence of atopic diseases respectively. Two dust mixes, both composed of 10 randomly selected dust samples from 349 Finnish and 417 Russian Karelian households were studied for bacterial biomarkers (DNA, Limulus-active endotoxin, 3-OH fatty acids, muramic acid) and for 16S rRNA gene sequences. Overall, the DNA cloning revealed more taxons (94 different genera) of dustborne bacteria than seen in any previous study on residential environments. Majority (67%) of the bacterial DNA clones in house dust from the low-allergy Russian Kareliarepresented Gram-positive bacteria (Firmicutes and Actinobacteria), predominantly Staphylococcaceae and Corynebacteriaceae. Russian Karelian dust showed up to 20-fold higher contents of muramic acid (marker of Gram-positive bacteria) and a sevenfold higher number of clones of animal-associated species, whereas in Finnish Karelian dust Gram-negatives (mainly Proteobacteria) predominated. Clones of plant-associated bacterial species and of chloroplast, indicating plant biomass, were more numerous in Finnish than in Russian Karelian dust. In conclusion, this study revealed major disparities between Finnish and Russian house dusts. The higher bacterial content and the predominance of Gram-positive bacteria in Russian dust may have implications for occurrence of atopy.
authors: Department of Applied Chemistry and Microbiology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland. jaakko.pakarinen@helsinki.fi
authors: Jaakko
authors: J
authors: Pakarinen
authors: Anne
authors: A
authors: Hyvärinen
authors: Mirja
authors: M
authors: Salkinoja-Salonen
authors: Sirpa
authors: S
authors: Laitinen
authors: Aino
authors: A
authors: Nevalainen
authors: Mika J
authors: MJ
authors: Mäkelä
authors: Tari
authors: T
authors: Haahtela
authors: Leena
authors: L
authors: von Hertzen
mesh_terms: D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004391:Dust / Q000032:analysis*; D004731:Endotoxins / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D005387:Finland; D020459:Genes, rRNA; D006094:Gram-Positive Bacteria / Q000145:classification* / Q000302:isolation & purification*; D006801:Humans; D008969:Molecular Sequence Data; D009112:Muramic Acids / Q000032:analysis; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012426:Russia; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004391:Dust; D004731:Endotoxins; D005227:Fatty Acids; D009112:Muramic Acids; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S