This week in Biofilms and Microbiomes: Monday August 15, 2016

A round-up of what we read last week in the media's coverage of biofilms and microbiomes research.

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In an intriguing research published in Nature Communications, researchers from the Michigan State University have shed light on the mechanism of electrical conductance in the biofilms of Geobacter sulfurreducens that grows on electrodes and generates electricity. The thick biofilm is a combination of cells packed with cytochromes – metal based proteins, and hair-like protein filaments called pili. Each bacterial cell in the biofilm generates electrical discharges that are transferred to the underlying electrode using a network of cytochromes which act as transformers and pili which function as power lines. In order to figure out the path of electron discharge across the biofilms and to the underlying electrode, the researchers used a pili-deficient mutant and a mutant that produced pili with reduced conductivity. These mutants were then used to grow biofilms of precise thickness and capacity to produce electricity. Interestingly, the team found that the network of cytochromes and pili can work together only for short distance (~10 μm) from the underlying electrode. The cytochromes lose their transfer speed once they get farther away. As the biofilms grow in thickness, reduced cytochromes accumulate and the pili provide the means for the cells to discharge respiratory electrons to the oxidized cytochromes below. In the absence of pili or in biofilms expressing poorly conductive pili, biofilm growth is limited to the thickness (~10 μm), where oxidized cytochromes are available to serve as electron acceptor to the cells. The ability of Geobacter bacteria to completely oxidize organic compounds to CO2 with an electrode poised at a metabolically oxidizing potential shows promise for the conversion of renewable biomass into electricity, hydrogen and/or liquid fuels in bioelectrochemical systems. The researchers conclude that understanding the multiple functions that pili play in G. sulfurreducens and their regulation may prove instrumental to improve the performance of Geobacter-driven electrochemical systems for applications in bioenergy. The paper was highlighted by Science Daily, Lab Manager and Futurity.

In a new paper published in Scientific Reports, researchers from the University of Alabama at Birmingham have suggested that early airway microbiome sets the stage for an infant’s pulmonary health, and any microbial imbalance in its development may be associated with subsequent lung disease. An analysis of tracheal aspirate samples from intubated extremely low birth weight (ELBW) preterm infants and full term (FT) infants, collected within six hours of their birth, revealed that the ELBW infants who went on to develop life-threatening bronchopulmonary dysplasia (BPD) showed abnormal microbial colonization patterns at birth, as compared to pre-term infants who did not get BPD. The airway microbiomes of ELBW infants with established BPD were found to be less diverse, and the pattern was very different from those of ELBW infants shortly after birth or full-term infants at birth. Further study of TA samples from extremely preterm infants in a serial fashion revealed consistent temporal changes in the airway microbiome of BPD-Predisposed ELBW infants as compared to BPD-Resistant infants from birth until the development of BPD – that of increasing abundance of Proteobacteria and decreased Firmicutes such as Lactobacillus. Genus Lactobacillus has been known to have strong anti-inflammatory properties and therefore a decrease in its abundance may contribute to the airway inflammation associated with BPD and resulting impairment in lung development. The researchers also validated the results of their study at a second medical center –Drexel University College of Medicine, Philadelphia. Relative decreased Lactobacillus abundance at birth in airway microbiome was found to be predictive of BPD in the validation cohort as well. Interestingly, the researchers found no differences between the respiratory microbiome of ELBW infants born by cesarean section versus those born by vaginal delivery, thus indicating that the microbial DNA in the airways is probably transplacentally derived, consistent with reports that the placenta has a rich microbiome. The paper was heavily publicized by many media outlets, including Science Daily,, and GEN News.

We’d love to hear what you’ve been reading this week. Please comment below.

Richa Dandona

Partnerships and Operations Manager, Nature Partner Journals, Nature Research