Balamuralikrishna Jayaprakash

Diversity of ribosomal 16S DNA- and RNA-based bacterial community in an office building drinking water system.

Next‐generation sequencing of 16S ribosomal RNA genes (rDNA) and ribosomal RNA (rRNA) was used to characterize water and biofilm microbiome collected from a drinking water distribution system of an office building after its first year of operation.

Crawling-induced floor dust resuspension affects the microbiota of the infant breathing zone

BackgroundFloor dust is commonly used for microbial determinations in epidemiological studies to estimate early-life indoor microbial exposures. Resuspension of floor dust and its impact on infant microbial exposure is, however, little explored. The aim of our study was to investigate how floor dust resuspension induced by an infant’s crawling motion and an adult walking affects infant inhalation exposure to microbes.ResultsWe conducted controlled chamber experiments with a simplified mechanical crawling infant robot and an adult volunteer walking over carpeted flooring. We applied bacterial 16S rRNA gene sequencing and quantitative PCR to monitor the infant breathing zone microbial content and compared that to the adult breathing zone and the carpet dust as the source. During crawling, fungal and bacterial levels were, on average, 8- to 21-fold higher in the infant breathing zone compared to measurements from the adult breathing zone. During walking experiments, the increase in microbial levels in the infant breathing zone was far less pronounced. The correlation in rank orders of microbial levels in the carpet dust and the corresponding infant breathing zone sample varied between different microbial groups but was mostly moderate. The relative abundance of bacterial taxa was characteristically distinct in carpet dust and infant and adult breathing zones during the infant crawling experiments. Bacterial diversity in carpet dust and the infant breathing zone did not correlate significantly.ConclusionsThe microbiota in the infant breathing zone differ in absolute quantitative and compositional terms from that of the adult breathing zone and of floor dust. Crawling induces resuspension of floor dust from carpeted flooring, creating a concentrated and localized cloud of microbial content around the infant. Thus, the microbial exposure of infants following dust resuspension is difficult to predict based on common house dust or bulk air measurements. Improved approaches for the assessment of infant microbial exposure, such as sampling at the infant breathing zone level, are needed.

Bacterial community changes in copper and PEX drinking water pipeline biofilms under extra disinfection and magnetic water treatment

To study the stability of biofilms and water quality in pilot scale drinking water copper and PEX pipes in changing conditions (extra disinfection, magnetic water treatment, MWT).

Indoor microbiota in severely moisture damaged homes and the impact of interventions

BackgroundThe limited understanding of microbial characteristics in moisture-damaged buildings impedes efforts to clarify which adverse health effects in the occupants are associated with the damage and to develop effective building intervention strategies. The objectives of this current study were (i) to characterize fungal and bacterial microbiota in house dust of severely moisture-damaged residences, (ii) to identify microbial taxa associated with moisture damage renovations, and (iii) to test whether the associations between the identified taxa and moisture damage are replicable in another cohort of homes. We applied bacterial 16S rRNA gene and fungal ITS amplicon sequencing complemented with quantitative PCR and chemical-analytical approaches to samples of house dust, and also performed traditional cultivation of bacteria and fungi from building material samples.ResultsActive microbial growth on building materials had significant though small influence on the house dust bacterial and fungal communities. Moisture damage interventions—including actual renovation of damaged homes and cases where families moved to another home—had only a subtle effect on bacterial community structure, seen as shifts in abundance weighted bacterial profiles after intervention. While bacterial and fungal species richness were reduced in homes that were renovated, they were not reduced for families that moved houses. Using different discriminant analysis tools, we were able identify taxa that were significantly reduced in relative abundance during renovation of moisture damage. For bacteria, the majority of candidates belonged to different families within the Actinomycetales order. Results for fungi were overall less consistent. A replication study in approximately 400 homes highlighted some of the identified taxa, confirming associations with observations of moisture damage and mold.ConclusionsThe present study is one of the first studies to analyze changes in microbiota due to moisture damage interventions using high-throughput sequencing. Our results suggest that effects of moisture damage and moisture damage interventions may appear as changes in the abundance of individual, less common, and especially bacterial taxa, rather than in overall community structure.

Quantitative assessment of microbes from samples of indoor air and dust

Different types of house dust samples are widely used as surrogates of airborne inhalation exposure in studies assessing health effects of indoor microbes. Here we studied—in a quantitative assessment—the representativeness of different house dust samples of indoor air (IA) and investigated seasonality and reproducibility of indoor samples. Microbial exposure was measured five times over 1 year in four rural and five urban Finnish homes. Six sampling methods were used: button inhalable aerosol sampler (actively collected personal and indoor air sampling), settled dust, floor dust, mattress dust and vacuum cleaner dust bag dust; the latter three referred to herein as “reservoir dust samples”. Using quantitative PCR, we quantified the fungal species Cladosporium herbarum, the fungal group Penicillium/Aspergillus/Paecilomyces variotii, total fungal DNA, and Gram-positive and Gram-negative bacteria. We observed significant differences in microbial levels between rural and urban homes, most pronounced for personal air samples. Fungal species and groups but not total fungal DNA in indoor air correlated moderately to well with reservoir dust and with personal air samples. For bacterial groups, the correlations between air and dust were generally lower. Samples of indoor air and settled dust reflected similarly seasonal variation in microbial levels and were also similar compositionally, as assessed by ratios of qPCR markers. In general, determinations from mattress dust and other reservoir samples were better reproducible in repeated assessments over time than from indoor air or settled dust. This study indicates that settled dust reflects the microbial composition of indoor air and responds similarly to environmental determinants. Reservoir dusts tend to predict better microbial levels in indoor air and are more reproducible. Sampling strategies in indoor studies need to be developed based on the study questions and may need to rely on more than one type of sample.

OP I – 4 Hyperactivity/inattention symptoms and early life indoor microbial diversity in urban children

Background/aim The immune system and gut microbiota may play a role in the cognitive development. The home microbiota are a source of microbial exposure affecting immunological and maybe gut microbiota development. Thus, it may contribute to cognitive development. Here, we assess the association between early life home dust microbial diversity and hyperactivity/inattention symptoms at 10 and 15 years old. Methods A random sample enriched with subjects with hyperactivity/inattention at age 15 years were selected from the German LISA birth cohort. Bedroom floor dust samples were collected at age 3 months and bacterial diversity was defined by richness (number of OTUs and Chao1) and diversity indices (Shannon and Simpson) calculated from Illumina MiSeq sequencing data of 16S rRNA gene DNA amplicons. Hyperactivity/inattention was defined based on the scores of the Strengths and Difficulties questionnaire (SDQ) at ages 10 (filled by parents) and at 15 years (self-administered), using a cut-off ≥7. With adjusted logistic regression models we investigate the associations between symptoms and 4 diversity indices in tertiles. At age 10, models were weighted by the inverse of the sampling weights. Results We included 226 individuals with information on indoor microbial diversity and hyperactivity/inattention symptoms. The median values of the diversity indices were higher among children without symptoms at age 10 for bacteria and at age 15 for fungi. After adjustment, hyperactivity/inattention at age 10 was inversely associated with bacterial richness (number of observed OTUs medium vs low diversity: OR=0.4; CI: 0.2 to 0.8; Chao1 medium vs low diversity: OR=0.3; CI: 0.1 to 0.5; high vs low: OR=0.3; CI: 0.2 to 0.6), and positively associated with fungal Chao1 (high vs low: OR=2.1; CI: 1.1 to 4.0), Shannon (medium vs low: OR=2.8; CI: 1.3 to 5.8), and Simpson (high vs low: OR=4.7; CI: 2.4 to 9.3). No significant associations were observed between the indices and hyperactivity/inattention at age 15. Conclusion Our results suggest that early life exposure to microbial diversity may play a role in the development of hyperactivity/inattention during childhood. Exposure to rich bacterial environment may protect from developing hyperactivity/inattention, while high fungal diversity may have the opposite effect. Further larger studies are needed to confirm our results.

Categorical performance characteristics of method ISO 7899-2 and indicator value of intestinal enterococci for bathing water quality monitoring

Intestinal enterococci indicate the fecal contamination of bathing waters. This study defines the performance characteristics of the reference method ISO 7899-2:2000 with water samples collected from inland and coastal bathing areas in Finland. From a total of 341 bacterial isolates grown on Slanetz and Bartley medium, 63.6% were confirmed as intestinal enterococci on bile aesculin agar. The partial 16S rRNA gene sequences showed that Enterococcus faecium and Enterococcus faecalis clades accounted for 93.1% of the confirmed isolates. The range of the false positive and false negative rate of the ISO 7899-2 was 0.0-18.5% and 5.6-57.1%, respectively, being affected by the presumptive colony count on the membrane. The analysis of multiple sample volumes is proposed to reach 10-100 colonies per membrane when 47 mm diameter membranes are used to prevent overestimation of low counts and underestimation of the high counts.

Additional file 3: Figure S1. of Indoor microbiota in severely moisture damaged homes and the impact of interventions

Mean relative abundance of the top 15 bacterial (A) and fungal (B) genera in dust samples from 41 moisture damage residences (floor dust living room (FDLR), floor dust form other rooms with moisture damage (FDOR), airborne settled dust (SD)). (TIFF 100xa0kb)