Effect of humic acids on numbers and activities of micro-organisms within physiological groups

Visser, S. A.

doi:10.1016/0146-6380(85)90055-5

Cited by 51 publications

(26 citation statements)

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“…The difference in quality between these two fractions was not as great as one might assume, however, considering that humic substances have been suggested to be highly refractory to bacterial utilization (Alexander 1965;Visser 1985) and to be used by bacteria only as cometabolites with nonhumic labile substrates (De Haan 1974) that were not present in H fractions in our study. In more recent work, humic substances have indeed been recognized as potentially important sources of bacterial production (Hessen 1985;Meyer et al 1987;Tranvik and Hijfle 1987;Tranvik and Sieburth 1989), although these studies did not directly measure the percent contribution of humic substances to total bacterial growth on DOC.…”

Section: Discussionmentioning

confidence: 53%

“…Humic substances have been shown to moderate bacterial activity, however (e.g. through trace-element chelation, effects on P cycling, and effects on enzyme activity: Stewart and Wetzel 1982;Visser 1985;Jones et al 1988) and to be cometabolized during bacterial utilization of more labile substrates (De Haan 1974, 1977. It is possible also that some fraction of aquatic humic substances is available as a primary bacterial substrate, and if so, humic substances could play an important role in supporting bacterial secondary production in aquatic ecosystems.…”

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confidence: 99%

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Bacterial production on humic and nonhumic components of dissolved organic carbon

Moran

Hodson

1990

Limnology & Oceanography

263

176

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Dissolved humic substances make up -50% or more of the dissolved organic carbon (DOC) in freshwater ecosystems, yet their trophodynamic roles remain unresolved. We separated DOC from two freshwater environments, a lake and a blackwater marsh, into two fractions, humic DOC and nonhumic DOC, using an XAD-8 resin to selectively adsorb the humic substances. Results of microcosm studies revealed that the humic fraction of DOC was used by natural bacterial assemblages from the lake and marsh as a C and energy source, as indicated both by increases in bacterial biovolume and rates of bacterial incorporation of [3H]thymidine. Humic substances supported fourfold less bacterial secondary production per unit of initial C, however, than did nonhumic substances from the same environment.Bacterial utilization of humic compounds accounted for a significant fraction of the total bacterial production on DOC, measured as increases in bacterial biovolume; humic substances supported an average of 22% of total growth on DOC from the lake and 53% of the total growth on DOC from the marsh. The relative bioavailability of both the humic and nonhumic fractions of DOC differed between the lake and blackwater marsh, with less bacterial production per unit of initial C occurring on marsh-derived dissolved compounds.In aquatic ecosystems, turnover of dissolved organic carbon (DOC) is almost exclusively the domain of bacteria as a result of their high numbers, large surface-to-volume ratios, and transport systems efficient at low substrate concentrations.Studies of bacterial utilization of DOC have indicated the existence of two distinct pools of dissolved compounds, one labile and one refractory, in most aquatic systems (Ogura 1975). Although the labile pool generally accounts for < 20% of the total DOC (Ogura 1975;Allen 1976), it turns over rapidly, on the order of hours to days, and is thought to support the bulk of DOC-based bacterial secondary production (Wright and Hobbie 1966;Allen 1976). The refractory pool is larger but turns over more slowly, on the order of weeks to months (Geller 1986) and therefore may be relatively unimportant as a substrate for bacterial growth. Neither of these two fractions of the DOC pool has been well characterized with respect to Acknowledgments We thank L. Pittman, G. Zeigler, E. Sheppard, and A. Brewer for technical assistance and J. Meyer, C. Strojan, and R. Wicks for helpful comments on this manuscript.

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Section: Discussionmentioning

confidence: 53%

mentioning

confidence: 99%

Bacterial production on humic and nonhumic components of dissolved organic carbon

Moran

Hodson

1990

Limnology & Oceanography

263

176

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“…(Sparling, 1992); hence, the lack of an effect of the LDPs on 467 MBC in the high-organic matter SC soil is not unexpected in a soil which already has 468 high levels of HS. There have been limited studies that investigate the effect of HA 469 on the soil microbial community although it has been found in a nutrient culture 470 medium that the structure of the humic product plays a role in promotion or 471 suppression of populations within the soil microbial community (Visser, 1985). with others,it is possible that application rates were too low to elicit a significant 479 agronomic response (Feibert et al, 2003, Hartz, 2010, Duval et al, 1998 …”

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Do lignite-derived organic amendments improve early-stage pasture growth and key soil biological and physicochemical properties?

et al. 2014

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“…With aerobes, exposure to humic materials has been shown to have various effects on metabolic activity in general and on the biodegradation of organic pollutant compounds in particular. For example, the growth of heterotrophic and nitrifying bacteria was reported to be stimulated by the addition of humic acids to culture media, and in both cases, the effect was attributed to the alteration of membrane characteristics such that nutrient uptake was enhanced (49,52). Exposure to humic acids improved the survival of Arthrobacter crystallopoietes by unknown mechanisms (22).…”

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Isolation of Soil Bacteria Adapted To Degrade Humic Acid-Sorbed Phenanthrene

Vacca¹,

Bleam

Hickey

2005

Appl Environ Microbiol

113

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The goal of these studies was to determine how sorption by humic acids affected the bioavailability of polynuclear aromatic hydrocarbons (PAHs) to PAH-degrading microbes. Micellar solutions of humic acid were used as sorbents, and phenanthrene was used as a model PAH. Enrichments from PAH-contaminated soils established with nonsorbed phenanthrene yielded a total of 25 different isolates representing a diversity of bacterial phylotypes. In contrast, only three strains of Burkholderia spp. and one strain each of Delftia sp. and Sphingomonas sp. were isolated from enrichments with humic acid-sorbed phenanthrene (HASP). Using [ 14 C]phenanthrene as a radiotracer, we verified that only HASP isolates were capable of mineralizing HASP, a phenotype hence termed "competence." Competence was an all-or-nothing phenotype: noncompetent strains showed no detectable phenanthrene mineralization in HASP cultures, but levels of phenanthrene mineralization effected by competent strains in HASP and NSP cultures were not significantly different. Levels and rates of phenanthrene mineralization exceeded those predicted to be supported solely by the metabolism of phenanthrene in the aqueous phase of HASP cultures. Thus, competent strains were able to directly access phenanthrene sorbed by the humic acids and did not rely on desorption for substrate uptake. To the best of our knowledge, this is the first report of (i) a selective interaction between aerobic bacteria and humic acid molecules and (ii) differential bioavailability to bacteria of PAHs sorbed to a natural biogeopolymer.

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Effect of humic acids on numbers and activities of micro-organisms within physiological groups

Cited by 51 publications

References 8 publications

Bacterial production on humic and nonhumic components of dissolved organic carbon

Bacterial production on humic and nonhumic components of dissolved organic carbon

Do lignite-derived organic amendments improve early-stage pasture growth and key soil biological and physicochemical properties?

Isolation of Soil Bacteria Adapted To Degrade Humic Acid-Sorbed Phenanthrene

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