Screening for bacterial–fungal associations in a south-eastern US salt marsh using pre-established fungal monocultures

Abstract

Both bacteria and fungi play critical roles in decomposition processes in many natural environments, yet only rarely have they been studied as an integrated community. We examined whether physical associations exist between individual bacterial and fungal species that co-occur on decaying smooth cordgrass, Spartina alterniflora, in a south-eastern US salt marsh. Fungal-pervaded decaying Spartina was used as "bait" for potential bacterial associates. The bundles (infiltrated with one of three dominant fungal members of the decomposer assemblage, or an autoclaved control) were placed in a salt marsh and collected biweekly for 6 weeks during the first experiment (late summer 2002), and weekly for 3 weeks during the second experiment (early summer 2003). Terminal-restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes was used to track colonization by bacterial taxa in association with the established fungal species. T-RFLP analysis of 18S-to-28S internal transcribed spacer (ITS) regions was used to monitor changes in fungal communities once bundles had been placed in the field. Results from both years were nearly identical, and showed that invasion by fungi other than the bait species was slow, resulting in a virtual fungal monoculture for several weeks into the experiments. Surprisingly, bacterial communities were unaffected by the identity of the fungal bait. Regardless of the fungal species, and even in the absence of prior fungal colonization, bacterial 16S rRNA profiles were remarkably similar. These results suggest that few species-specific associations, either positive or negative, exist between bacterial and fungal members of the Spartina decomposer community during initial colonization.

Comparison of rRNA and Polar-Lipid-Derived Fatty Acid Biomarkers for Assessment of 13 C-Substrate Incorporation by Microorganisms in Marine Sediments

“…Small-subunit (SSU) rRNA or rRNA gene sequences are widely used to identify microorganisms in natural systems (16,43,62), and they can provide much greater phylogenetic resolution than lipids. Several methods that combine the advantages of molecular community analysis and labeling with 13 Csubstrates have been developed.…”

GÉNEROS DE HONGOS NECROFÍTICOS ASOCIADOS A HOJAS DE Spartina argentinensis Parodi Y Panicum prionitis Ness en Argentina

“…Para este fin, el alto porcentaje de lignina de ambas especies es la principal barrera a vencer (Himmel et al, 2007;Gómez et al, 2008). Existe información sobre descomposición de especies del género Spartina creciendo en costas marinas, donde se señala la relevancia que tienen los hongos en el proceso (Gessner y Goos, 1973;Newell y Porter, 2000;Newell 2001a;Newell 2001b;Buchan et al, 2002;Kohlmeyer y Volkmann-Kohlmeyer, 2002;Blum et al, 2004;Lyons et al, 2005;Lyons et al, 2010) puesto que este grupo de organismos se destaca por su capacidad ligninolítica (Benner et al, 1986;Newell and Porter, 2000).…”

Ascomycete fungal communities associated with early decaying leaves of Spartina spp. from central California estuaries

“…Fungi, together with bacteria, represent the major mechanism for the breakdown of vascular plant lignins (Benner et al 1986;Newell and Porter 2000). Previous studies of the fungal community of US salt marshes have focused on the east coast (Blum et al 2004;Buchan et al 2002;Lyons et al 2005;. Several species of ascomycetous fungi have been identified as major decomposers of S. alterniflora blades, based on traditional culture-and microscopy-based methods (Kohlmeyer and Volkmann-Kohlmeyer 2002;Newell 2001aNewell , 2001bNewell and Porter 2000) as well as molecular approaches (Buchan et al 2002(Buchan et al , 2003Lyons et al 2005).…”

“…Previous studies of the fungal community of US salt marshes have focused on the east coast (Blum et al 2004;Buchan et al 2002;Lyons et al 2005;. Several species of ascomycetous fungi have been identified as major decomposers of S. alterniflora blades, based on traditional culture-and microscopy-based methods (Kohlmeyer and Volkmann-Kohlmeyer 2002;Newell 2001aNewell , 2001bNewell and Porter 2000) as well as molecular approaches (Buchan et al 2002(Buchan et al , 2003Lyons et al 2005). Although at least 28 marine ascomycetes have been identified on Spartina (Kohlmeyer and Volkmann-Kohlmeyer 2002), the two most common species are Phaeosphaeria spartinicola and Mycosphaerella sp.…”