Alteration of a Salt Marsh Bacterial Community by Fertilization with Sewage Sludge

Abstract

The effects of long-term fertilization with sewage sludge on the aerobic, chemoheterotrophic portion of a salt marsh bacterial community were examined. The study site in the Great Sippewissett Marsh, Cape Cod, Mass., consisted of experimental plots that were treated with different amounts of commercial sewage sludge fertilizer or with urea and phosphate. The number of CFUs, percentage of mercury-and cadmium-resistant bacteria, and percentage of antibiotic-resistant bacteria were all increased in the sludge-fertilized plots. Preliminary taxonomic characterization showed that sludge fertilization markedly altered the taxonomic distribution and reduced diversity within both the total heterotrophic and the mercury-resistant communities. In control plots, the total heterotrophic community was fairly evenly distributed among taxa and the mercury-resistant community was dominated by Pseudomonas spp. In sludge-fertilized plots, both the total and mercury-resistant communities were dominated by a single Cytophaga sp.

The mercury resistance (mer) operon in a marine gliding flavobacterium,Tenacibaculum discolor9A5

“…In a previous study of bacteria cultured from a New England salt marsh fertilized with Hg-contaminated sewage sludge (Hamlett, 1986), we found that the predominant mercury-resistant bacteria, comprising 20-50% of Hg r isolates belonged to a single species of iridescent gliding marine bacteria in phylum Bacteroidetes, which we subsequently identified as Tenacibaculum discolor Supporting information, Figs S1 & S2). These strains did not, however, hybridize with DNA probes from Tn21 or Tn501 mercury resistance (mer) operons (Hamlett & Weiss, 1985), nor were we able to amplify mer genes with mer PCR primers designed for a broad range of gram-negative bacteria .…”

“…Although mercury compounds are among the most toxic substances known (Nascimento & Chartone-Souza, 2003), a wide variety of bacteria from both clinical and environmental sources, including the deeply diverged bacterial phylum Thermus/Deinococcus (Wang et al, 2009) and the archaeon Sulfolobus (Schelert et al, 2004), have genes that confer resistance to the toxic effects of mercury (Barkay et al, 2003;Silver & Phung, 2005). Little is known, however, about the genetic determinants of mercury resistance in marine bacteria, and none have been characterized in one major bacterial phylumthe phylum Bacteroidetes (also known as the Cytophaga-Flavobacterium-Bacteroides group), despite their apparent importance in mercury-resistant bacterial communities (Gachhui et al, 1997;Rasmussen et al, 2008), especially in marine environments (Hamlett, 1986;Nieto et al, 1989;Møller et al, 2011).…”

Nitrogen substrate–dependent nitrous oxide cycling in salt marsh sediments

“…To investigate the effects of nutrient enrichment on salt marsh ecosystems, a long-term fertilization project was initiated in the 1970s in the Great Sippewissett Marsh, Falmouth, Massachusetts, by Valiela, Teal, and Sass (1973) and has been maintained without interruption. The results of long-term fertilization have included increases in aboveground biomass (Valiela, Teal, and Sass 1975;Howes, Dacey, and Goehringer 1986), loss of Spartina alterniflora and an increase in Distichlis spicata (Fox, Valiela, and Kinney 2012), and the alteration of microbial communities in high-nutrient environments (Hamlett 1986;Bowen et al 2013). In addition, elevated rates of denitrification (Koop-Jakobsen and Giblin 2010; Kinney and Valiela 2013) and coupled nitrification-denitrification (Hamersley and Howes 2005) were associated with increasing fertilization.…”

Association of mercury resistance with antibiotic resistance in the gram-negative fecal bacteria of primates

“…The incidence of Hg r bacteria increased in mercury-polluted soil and water (2,21,26) and in Japanese hospitals in a manner coincident with the use of mercurial antiseptics (37). Thus, the prevalence of Hg-metabolizing bacteria in a niche varies in response to Hg exposure in that environment.…”