« Go Back

Research Containing: Colony Count

Space Environmental Factor Impacts upon Murine Colon Microbiota and Mucosal Homeostasis

by on 22 August 2016in Biology & Biotechnology No comment

Astronaut intestinal health may be impacted by microgravity, radiation, and diet. The aim of this study was to characterize how high and low linear energy transfer (LET) radiation, microgravity, and elevated dietary iron affect colon microbiota (determined by 16S rDNA pyrosequencing) and colon function. Three independent experiments were conducted to achieve these goals: 1) fractionated low LET gamma radiation (137Cs, 3 Gy, RAD), high Fe diet (IRON) (650 mg/kg diet), and a combination of low LET gamma radiation and high Fe diet (IRON+RAD) in male Sprague-Dawley rats; 2) high LET 38Si particle exposure (0.050 Gy), 1/6 G partial weight bearing (PWB), and a combination of high LET38Si particle exposure and PWB in female BalbC/ByJ mice; and 3) 13 d spaceflight in female C57BL/6 mice. Low LET radiation, IRON and spaceflight increased Bacteroidetes and decreased Firmicutes. RAD and IRON+RAD increased Lactobacillales and lowered Clostridiales compared to the control (CON) and IRON treatments. Low LET radiation, IRON, and spaceflight did not significantly affect diversity or richness, or elevate pathogenic genera. Spaceflight increased Clostridiales and decreased Lactobacillales, and similar trends were observed in the experiment using a ground-based model of microgravity, suggesting altered gravity may affect colonic microbiota. Although we noted no differences in colon epithelial injury or inflammation, spaceflight elevated TGFbeta gene expression. Microbiota and mucosal characterization in these models is a first step in understanding the impact of the space environment on intestinal health.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26083373

Microbial monitoring of spacecraft and associated environments

by on 9 June 2015in Biology & Biotechnology No comment

Rapid microbial monitoring technologies are invaluable in assessing contamination of spacecraft and associated environments. Universal and widespread elements of microbial structure and chemistry are logical targets for assessing microbial burden. Several biomarkers such as ATP, LPS, and DNA (ribosomal or spore-specific), were targeted to quantify either total bioburden or specific types of microbial contamination. The findings of these assays were compared with conventional, culture-dependent methods. This review evaluates the applicability and efficacy of some of these methods in monitoring the microbial burden of spacecraft and associated environments. Samples were collected from the surfaces of spacecraft, from surfaces of assembly facilities, and from drinking water reservoirs aboard the International Space Station (ISS). Culture-dependent techniques found species of Bacillus to be dominant on these surfaces. In contrast, rapid, culture-independent techniques revealed the presence of many Gram-positive and Gram-negative microorganisms, as well as actinomycetes and fungi. These included both cultivable and noncultivable microbes, findings further confirmed by DNA-based microbial detection techniques. Although the ISS drinking water was devoid of cultivable microbes, molecular-based techniques retrieved DNA sequences of numerous opportunistic pathogens. Each of the methods tested in this study has its advantages, and by coupling two or more of these techniques even more reliable information as to microbial burden is rapidly obtained.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/14749906

Evidence of pathogenic microbes in the International Space Station drinking water: reason for concern?

by on 9 June 2015in Biology & Biotechnology No comment

Molecular analyses were carried out on four preflight and six postflight International Space Station (ISS)-associated potable water samples at various stages of purification, storage, and transport, to ascertain their associated microbial diversities and overall microbial burdens. Following DNA extraction, PCR amplification, and molecular cloning procedures, rDNA sequences closely related to pathogenic species of Acidovorax, Afipia, Brevundimonas, Propionibacterium, Serratia, and others were recovered in varying abundance. Retrieval of sequences arising from the iodine (biocide)-reducing Delftia acidovorans in postflight waters is also of concern. Total microbial burdens of ISS potable waters were derived from data generated by an ATP-based enumeration procedure, with results ranging from 0 to 4.9 x 10(4) cells/ml. Regardless of innate biases in sample collection and analysis, such circumstantial evidence for the presence of viable, intact pathogenic cells should not be taken lightly. Implementation of new cultivation approaches and/or viability-based assays are requisite to confirm such an occurrence.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/15880908

Spaceflight promotes biofilm formation by Pseudomonas aeruginosa

by on 9 June 2015in Biology & Biotechnology No comment

Understanding the effects of spaceflight on microbial communities is crucial for the success of long-term, manned space missions. Surface-associated bacterial communities, known as biofilms, were abundant on the Mir space station and continue to be a challenge on the International Space Station. The health and safety hazards linked to the development of biofilms are of particular concern due to the suppression of immune function observed during spaceflight. While planktonic cultures of microbes have indicated that spaceflight can lead to increases in growth and virulence, the effects of spaceflight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Space Shuttle Atlantis missions: STS-132 and STS-135, and the biofilms formed during spaceflight were characterized. Spaceflight was observed to increase the number of viable cells, biofilm biomass, and thickness relative to normal gravity controls. Moreover, the biofilms formed during spaceflight exhibited a column-and-canopy structure that has not been observed on Earth. The increase in the amount of biofilms and the formation of the novel architecture during spaceflight were observed to be independent of carbon source and phosphate concentrations in the media. However, flagella-driven motility was shown to be essential for the formation of this biofilm architecture during spaceflight. These findings represent the first evidence that spaceflight affects community-level behaviors of bacteria and highlight the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/23658630

The effect of spaceflight on growth of Ulocladium chartarum colonies on the international space station

by on 9 June 2015in Biology & Biotechnology No comment

The objectives of this 14 days experiment were to investigate the effect of spaceflight on the growth of Ulocladium chartarum, to study the viability of the aerial and submerged mycelium and to put in evidence changes at the cellular level. U. chartarum was chosen for the spaceflight experiment because it is well known to be involved in biodeterioration of organic and inorganic substrates covered with organic deposits and expected to be a possible contaminant in Spaceships. Colonies grown on the International Space Station (ISS) and on Earth were analysed post-flight. This study clearly indicates that U. chartarum is able to grow under spaceflight conditions developing, as a response, a complex colony morphotype never mentioned previously. We observed that spaceflight reduced the rate of growth of aerial mycelium, but stimulated the growth of submerged mycelium and of new microcolonies. In Spaceships and Space Stations U. chartarum and other fungal species could find a favourable environment to grow invasively unnoticed in the depth of surfaces containing very small amount of substrate, posing a risk factor for biodegradation of structural components, as well as a direct threat for crew health. The colony growth cycle of U. chartarum provides a useful eukaryotic system for the study of fungal growth under spaceflight conditions.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/23637980