Experimental evidence for the impact of soil viruses on carbon cycling during surface plant litter decomposition

Abstract

To date, the potential impact of viral communities on biogeochemical cycles in soil has largely been inferred from correlational evidence, such as virus-driven changes in microbial abundances, viral auxiliary metabolic genes, and links with soil physiochemical properties. To more directly test the impact of soil viruses on carbon cycling during plant litter decomposition, we added concentrated viral community suspensions to complex litter decomposer communities in 40-day microcosm experiments. Microbial communities from two New Mexico alpine soils, Pajarito (PJ) and Santa Fe (SF), were inoculated onto grass litter on sand, and three treatments were applied in triplicate to each set of microcosms: addition of buffer (no added virus), live virus (+virus), or killed-virus (+killed-virus) fractions extracted from the same soil. Significant differences in respiration were observed between the +virus and +killed-virus treatments in the PJ, but not the SF microcosms. Bacterial and fungal community composition differed significantly by treatment in both PJ and SF microcosms. Combining data across both soils, viral addition altered links between bacterial and fungal diversity, dissolved organic carbon and total nitrogen. Overall, we demonstrate that increasing viral pressure in complex microbial communities can impact terrestrial biogeochemical cycling but is context-dependent.

Diversity in the soil virosphere: to infinity and beyond?

“…Consistent with established patterns for other soil microbes [9], viral community composition tends to vary with soil depth, pH, moisture, and across soil compartments, such as between rhizospheres and bulk soils [30,33,43,57,58,[61][62][63][64][65]. Early evidence also supports reproducible links between viruses and many components of the terrestrial carbon (C) cycle [33,57,64,[66][67][68][69]. For instance, viral expression of C-cycling genes to facilitate host viability during infection may explain the frequent detection of virus-encoded glycoside hydrolases and other carbohydrate-active enzymes (CAZymes) in soil [56,57,62,66].…”

Simulated nitrogen deposition and precipitation events alter microbial carbon cycling during early stages of litter decomposition

“…More recently microbial community composition was found to create signi cant variation in carbon ow measured as DOC and respiration (CO 2 ) across litter types of varying substrate quality during short-term litter decomposition (Kroeger et al 2021). These ndings add to a growing body of literature (Albright et al 2020b(Albright et al , a, 2022Campbell et al 2022) that highlight the important in uence of microbial community composition on carbon ow from litter decomposition. In these previous studies, large microbiome effects were quanti ed unambiguously by holding environmental conditions constant, isolating the litter microbiome as the single factor driving variation in carbon ow.…”

Propagation of viral genomes by replicating ammonia-oxidising archaea during soil nitrification

“…Recent advances have demonstrated that soil virus communities are dynamic in a wide range of soils [e.g. 8 , 9 ] and augmenting virus loads modulate C and N fluxes [ 10 , 11 ]. Nevertheless, identifying active interactions with specific populations or functional groups in soil remains challenging due to structural complexity and the vast diversity of hosts and viruses.…”