Converting a Solventogen into an Acetogen: Functional Expression of an Acetyl Coenzyme A Synthase in Clostridium acetobutylicum
Engineering a heterologous acetogenic Wood-Ljungdahl pathway (WLP) in the industrial solventogen Clostridium acetobutylicum would minimize CO2 and H2 release, thereby enabling the conversion of renewable carbohydrates into a broad spectrum of metabolites at higher yields than are currently possible. A key challenge towards that goal is the functional expression of the core WLP enzyme, acetyl coenzyme A (CoA) synthase (ACS), which synthesizes acetyl-CoA from CO and an activated methyl group. Fast and Papoutsakis (e02307-17) adapted the classical in vitro ACS carbonyl-carbon exchange assay to the in vivo setting, thus demonstrating the in vivo function of the heterologous C. ljungdahlii ACS in C. acetobutylicum.
Mineral Iron as a Micronutrient Source for Snow Algal Communities
Snow algae have recently caught the attention of microbiologists and physicists alike because of their conspicuous formation of brightly colored red to green blooms in snowpack. Dense blooms can reduce snow albedo in seasonal and permanent continental and alpine snow environments. Iron, a key micronutrient supporting algal growth, may be limited in snow due to its low solubility in circumneutral pH systems. Experimentation by Harrold et al. (e02322-17) with a snow algal-bacterial coculture provides unequivocal evidence that some iron-bearing minerals can enhance snow algal growth rates in otherwise iron-depleted systems and suggests that Fe-bearing mineral dust could play a role in supporting albedo-altering algal blooms.
Microbiome Inhibition of a Parasite in Bumble Bees
The gut microbiome of bumble bees can protect against infection by a common protozoan parasite, Crithidia bombi. However, the mechanism behind this inhibition is unknown. Mockler and colleagues (e02335-17) transplanted different microbiomes into germfree bees and determined their ability to resist C. bombi. They found that greater gut community diversity, higher bacterial abundance, and the presence of certain bacteria (particularly an Apibacter sp.) all resulted in lower rates of C. bombi infection. This work reveals potential interactions between the microbiome and a parasite that impact the health of a key insect pollinator.
Polyphosphate-Accumulating Bacteria in the Oral Cavity
Bacteria associated with dental decay have been studied primarily for their ability to produce tooth-dissolving acid. However, research in the marine environment shows that some bacteria can alter the solubility of calcium phosphate minerals through the dynamic uptake or release from cells of phosphorus, which is stored in the form of a polymer known as polyphosphate. Breiland et al. (e02440-17) show that dental plaque contains abundant polyphosphate-accumulating bacteria. Chemical modeling, along with phosphorus uptake studies in Lactobacillus rhamnosus, suggests that bacteria in plaque have the potential to contribute to dental decay by removing phosphate from the microenvironment at the saliva/tooth interface.
Novel Method Uncovers the Diversity of Bacterial Dispersers on Soil-Like Surfaces
Little is known of the dispersal ability of environmental microbial communities, even though dispersal is a key process in bacterial community assembly. In a method developed by Krüger et al. (e02857-17), communities disperse under controlled hydration conditions on surfaces mimicking soil and efficient dispersers are recovered and characterized. Analysis of soil and lake water bacterial communities revealed surprisingly rapid dispersal under dry conditions. The disperser subcommunities had a narrow phylogenetic distribution and were dominated by Pseudomonas and Aeromonas bacteria in soil and lake communities, respectively. This discovery brings us a step closer to assessing bacterial dispersal under environmentally relevant conditions.
- Copyright © 2018 American Society for Microbiology.
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- Converting a Solventogen into an Acetogen: Functional Expression of an Acetyl Coenzyme A Synthase in Clostridium acetobutylicum
- Mineral Iron as a Micronutrient Source for Snow Algal Communities
- Microbiome Inhibition of a Parasite in Bumble Bees
- Polyphosphate-Accumulating Bacteria in the Oral Cavity
- Novel Method Uncovers the Diversity of Bacterial Dispersers on Soil-Like Surfaces
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