Airborne Prokaryote and Virus Abundance Over the Red Sea

Aeolian dust exerts a considerable influence on atmospheric and oceanic conditions negatively impacting human health, particularly in arid and semi-arid regions like Saudi Arabia. Aeolian dust is often characterized by its mineral and chemical composition; however, there is a microbiological component of natural aerosols that has received comparatively little attention. Moreover, the amount of materials suspended in the atmosphere is highly variable from day to day. Thus, understanding the variability of atmospheric dust loads and suspended microbes throughout the year is essential to clarify the possible effects of dust on the Red Sea ecosystem. Here, we present the first estimates of dust and microbial loads at a coastal site on the Red Sea over a 2-year period, supplemented with measurements from dust samples collected along the Red Sea basin in offshore waters. Weekly average dust loads from a coastal site on the Red Sea ranged from 4.6 to 646.11 μg m−3, while the abundance of airborne prokaryotic cells and viral-like particles (VLPs) ranged from 77,967 to 1,203,792 cells m−3 and from 69,615 to 3,104,758 particles m−3, respectively. To the best of our knowledge, these are the first estimates of airborne microbial abundance in this region. The elevated concentrations of resuspended dust particles and suspended microbes found in the air indicate that airborne microbes may potentially have a large impact on human health and on the Red Sea ecosystem.En prens

Engineered production of isoprene from the model green microalga Chlamydomonas reinhardtii

Isoprene is a clear, colorless, volatile 5-carbon hydrocarbon that is one monomer of all cellular isoprenoids and a platform chemical with multiple applications in industry. Many plants have evolved isoprene synthases (IspSs) with the capacity to liberate isoprene from dimethylallyl diphosphate (DMADP) as part of cellular thermotolerance mechanisms. Isoprene is hydrophobic and volatile, rapidly leaves plant tissues and is one of the main carbon emission sources from vegetation globally. The universality of isoprenoid metabolism allows volatile isoprene production from microbes expressing heterologous IspSs. Here, we compared heterologous overexpression from the nuclear genome and localization into the plastid of four plant terpene synthases (TPs) in the green microalga Chlamydomonas reinhardtii. Using sealed vial mixotrophic cultivation, direct quantification of isoprene production was achieved from the headspace of living cultures, with the highest isoprene production observed in algae expressing the Ipomoea batatas IspS. Perturbations of the downstream carotenoid pathway through keto carotenoid biosynthesis enhanced isoprene titers, which could be further enhanced by increasing flux towards DMADP through heterologous co-expression of a yeast isopentenyl-DP delta isomerase. Multiplexed controlled-environment testing revealed that cultivation temperature, rather than illumination intensity, was the main factor affecting isoprene yield from the engineered alga. This is the first report of heterologous isoprene production from a eukaryotic alga and sets a foundation for further exploration of carbon conversion to this commodity chemical

Corrigendum: Resolving the abundance and air-sea fluxes of airborne microorganisms in the North Atlantic Ocean

A corrigendum on Resolving the abundance and air-sea fluxes of airborne microorganisms in the North Atlantic Ocean by Mayol, E., Jiménez, M. A., Herndl, G. J., Duarte, C. M., and Arrieta, J. M. (2014). Front. Microbiol. 5:557. doi: 10.3389/fmicb.2014.00557 We found an implementation error in the calculation of the deposition velocity (vd) which, in turn, affected all the estimated vd-depending parameters (deposition flux, residence time, and traveled distance by microorganisms). Deposition fluxes are now somewhat lower than previously estimated, resulting in residence times and traveled distances longer than those previously estimated. In addition, the spray fluxes were calculated using a spray generation function (dF/dr0) valid for droplets of radii between 0.5 and 12 μm proposed by Blanchard (1963) and Gathman (1982) as corrected by Andreas et al. (1995). However, in the calculation of dF/dr0, we exceeded this valid range of radii given that we included droplets with radii from 0.2 μm according to the small size of some microbial cells. Thus, a different formulation of dF/dr0, developed by Gong (2003), is now used for the estimation of spray fluxes of microbes, which is valid even for small droplets from a radius of 0.07 μm. Below, we offer a new corrected version of the paragraphs affected by corrections along the text. In addition, we show corrected versions of Figure 1 (forward trajectories according residence times), Figure 3 (deposition velocity values), Figure 5 (spray and deposition fluxes), Figure 6 (Net fluxes), and Table 1. The authors apologize for the errors in the estimates reported in the original manuscript. These corrections only affect the magnitude of some of the reported variables and even though they do not change the scientific conclusions of the article they are reported here for accuracy and reproducibility