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10 páginas.- 4 figuras.- 4 tablas.- 45 referencias.- The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.2c03149, Recent research has demonstrated that chemotactic bacteria can disperse inside microsized pores while traveling toward favorable conditions. Microbe–microbe cotransport might enable nonmotile bacteria to be carried with motile partners to enhance their dispersion and reduce their deposition in porous systems. The aim of this study was to demonstrate the enhancement in the dispersion of nonmotile bacteria (Mycobacterium gilvum VM552, a polycyclic aromatic hydrocarbon-degrader, and Sphingobium sp. D4, a hexachlorocyclohexane-degrader, through micrometer-sized pores near the exclusion-cell-size limit, in the presence of motile Pseudomonas putida G7 cells. For this purpose, we used bioreactors equipped with two chambers that were separated with membrane filters with 3, 5, and 12 μm pore sizes and capillary polydimethylsiloxane (PDMS) microarrays (20 μm × 35 μm × 2.2 mm). The cotransport of nonmotile bacteria occurred exclusively in the presence of a chemoattractant concentration gradient, and therefore, a directed flow of motile cells. This cotransport was more intense in the presence of larger pores (12 μm) and strong chemoeffectors (γ-aminobutyric acid). The mechanism that governed cotransport at the cell scale involved mechanical pushing and hydrodynamic interactions. Chemotaxis-mediated cotransport of bacterial degraders and its implications in pore accessibility opens new avenues for the enhancement of bacterial dispersion in porous media and the biodegradation of heterogeneously contaminated scenarios., This research was funded by European Union's Horizon 2020 research and innovation program under the Marie Sklodowska- Curie grant agreement no. 895340 (BIOTAC project) and by the Spanish Ministry of Science and Innovation (PID2019- 109700RB-C21) .

5 páginas.- 1 figura.- 24 referencias, Soils are complex and dynamic systems that perform essential functions contributing to the sustainability of terrestrial ecosystems and the support of life. They participate in a wide variety of ecosystem functions/services (e.g., Baveye et al., 2016), including those related to the production of biomass, the regulation of carbon and nutrient cycles, and the regulation of water resources and air quality, due to their filtering and buffering capacity.

16 páginas.- 4 figuras.- referencias, In 1991, at the launch of a national symposium devoted to soil structure, the Australian Society of Soil Science invited Professor John Letey to deliver a keynote address, which was later published in the society’s journal. In his lecture, he shared the outcome of his reflexion about what the assessment of soil structure should amount to, in order to produce useful insight into the functioning of soils. His viewpoint was that the focus should be put on the openings present in the structure, rather than on the chunks of material resulting from its mechanical dismantlement. In the present article, we provide some historical background for Letey’s analysis, and try to explain why it took a number of years for the paradigm shift that he advocated to begin to occur. Over the last decade, his perspective that soil structure needs to be characterised via nondestructive methods appears to have gained significant momentum, which is likely to increase further in the near future, as we take advantage of recent technological advances. Other valuable lessons that one can derive from Letey’s pioneering article relate to the extreme value for everyone, even neophytes, to constantly ask questions about where research on given topics is heading, what its goals are, and whether the methods that are used at a certain time are optimal, Partial financial support obtained through a grant from the Agence Nationale de la Recherche (ANR, France) to project Soilμ3D, directed by Dr. Patricia Garnier.

2 páginas.- 6 referencias.- Free Accessr.- This is a letter to Waring et al., https://doi.org/10.1111/gcb.15850, In an article published recently, Waring et al. (2020) introduced a conceptual framework, named PROMISE, to explore controls on belowground carbon cycling. This “fundamentally novel approach to measuring and modeling critical carbon cycle processes” represents soil pore space as an array of possible particle locations belonging to one of three pore size classes. Several aspects of this conceptual framework raise questions about its adequacy to describe the fate of carbon in heterogeneous soils. More than a decade ago already, Kuka et al. (2007) advocated the significance of the size of pores when modeling carbon turnover in soils and proposed a model, called CIPS (“Carbon Turnover in Pore Space”), which is not mentioned by Waring et al. (2020) even though in several respects, CIPS is very similar to PROMISE, and shares the same aims and approach. In CIPS, pores are also divided into three classes according to their size. Like PROMISE, CIPS does not assume any spatial arrangement, distance, or differences in connectivity among the three classes of pores.