Distribution of zinc-tolerant bacteria in stream sediments

Hornor, Sally G.; Hilt, Beth A.

doi:10.1007/bf00008735

Cited by 16 publications

(10 citation statements)

References 12 publications

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“…For zinc, tolerance was already elevated in samples upstream from the Eindergatloop, whereas cadmium sensitivity was significantly reduced only at extremely high levels of this metal in the two most polluted Dommel sites ( Figure 5). Our observations corroborate earlier ones on the increased incidence of zinc tolerant bacteria in metal polluted stream sediments (Hornor and Hilt 1985;Chappel and Goulder 1994). The precipitation mechanisms mentioned above are likely to protect intact microbenthic assemblages.…”

Section: Bacterial Thymidine Incorporationsupporting

confidence: 82%

Induced Metal Tolerance in Microbenthic Communities from Three Lowland Rivers with Different Metal Loads

Lehmann

Tubbing

Admiraal

1999

Arch. Environ. Contam. Toxicol.

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The response of microbenthic communities to sustained metal stress was studied in three lowland rivers with different levels of pollution. Tolerance against zinc and cadmium was determined in short-term toxicity tests with microbenthic assemblages colonizing glass discs. Photosynthetic activity served as an endpoint in tests for algae, whereas for bacteria thymidine incorporation was determined. For bacterial assemblages from unpolluted locations, EC50 values in short-term tests ranged between 6.7 and 56.2 &mgr;M zinc, and 8.7 and 25.5 &mgr;M cadmium, respectively. Bacterial assemblages from the two most polluted sites were significantly more tolerant for zinc (EC50: 994 &mgr;M and >1,000 &mgr;M) and cadmium (EC50: 218 &mgr;M and 154 &mgr;M). Results indicated a shift in community composition toward pollution-adapted organisms when a threshold concentration of 1 &mgr;M zinc is exceeded. Although an increasing community tolerance was also indicated for algae, EC50 values for microbenthic algae from all sites exceeded in most cases the highest metal concentrations tested (Zn: 1,000 &mgr;M; Cd: 320 &mgr;M). Since species composition of algal assemblages was found to change at much lower metal levels, it is concluded that short-term toxicity tests measuring photosynthesis inhibition do not reflect well the long-term effects of these metals. Toxic effects of metals on both algal and bacterial assemblages are attenuated by precipitation and complexing capacities of the biofilm.

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Section: Bacterial Thymidine Incorporationsupporting

confidence: 82%

Induced Metal Tolerance in Microbenthic Communities from Three Lowland Rivers with Different Metal Loads

Lehmann

Tubbing

Admiraal

1999

Arch. Environ. Contam. Toxicol.

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“…This indicates that water microbial community is more sensitive to metal toxicity than sediment community. Hornor and Hilt have made similar observations, where bacteria in polluted site are more tolerant to metal than those in unpolluted sediment [14]. Hornor and Hilt also observed that the presence of Zn-tolerant bacteria correlated with the degree of heavy metal contamination.…”

Section: +mentioning

confidence: 68%

Toxicity of Zinc to Heterotrophic Bacteria From a Tropical River Sediment

Nweke¹

2007

Appl Ecol Env Res

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Abstract. Tolerance to Zn 2+ by pure cultures of Bacillus, Salmonella and Arthrobacter species isolated from New Calabar River sediment was assessed through dehydrogenase assay. The cultures were exposed to Zn 2+ concentrations of 0.2 to 2.0 mM in a nutrient broth-glucose-TTC medium. The responses of the bacterial strains varied with Zn 2+ concentration. In Salmonella sp. SED2, Zn 2+ stimulated dehydrogenase activity at 0.2 mM. In Bacillus sp. SED1 and Arthrobacter sp. SED4, dehydrogenase activity was progressively inhibited with increasing Zn 2+ concentration. The IC 50 ranges from 0.206 ± 0.030 to 0.807 ± 0.066 mM. Total inhibition of dehydrogenase activity was observed at concentrations ranging from 1.199 ± 0.042 to 1.442 ± 0.062. The order of zinc tolerance is: Salmonella sp. SED2 > Arthrobacter sp. SED4 > Bacillus sp. SED1. The result of the in vitro study indicated that Zinc is potentially toxic to sediment bacteria and could pose serious threat to their metabolism in natural environments.

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“…CFU from dosed (1.0 mg Zn 1-I) epilithon showed approximately equal numbers on zinc amended and unamended media after 20 days of dosing indicating the presence of zinctolerant heterotrophic populations. A correlation between zinc-tolerant heterotrophs and zinc concentration has been noted previously in stream sediments (Hornor & Hilt, 1985). Total CFU of marine bacterioplankton decrease upon addition of mercury but recover over time and subsequently remain at least equal to control values, demonstrating development of tolerance to mercury .…”

Section: Discussionmentioning

confidence: 79%

“…Total heterotrophic plate counts, expressed as colony forming units (CFU), were determined for the initial and 20th days during the A85 study using the method of Hornor & Hilt (1985). Appropriate dilutions of epilithon homogenate from each stream were spread onto triplicate plates containing 114 strength Nutrient Agar (Difco) amended with 0.0, 1.0, or 10.0 mg Zn 1-'.…”

Section: Methodsmentioning

confidence: 99%

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Evidence of structural and functional adaptation in epilithon exposed to zinc

1989

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Artificial streams were used to study the effect of chronic zinc dosing (0.00,0.05 or 1.00 mg Zn 1-') on epilithic communities during summer and early fall, 1984 and 1985. Following zinc addition, epilithon was periodically measured for '4C-glucose and 14C-glutamate respiration, ash-free dry weight (AFDW), protein, carbohydrate, chlorophyll a (Chl a), pheophytin a (pheo a), and colony forming units (CFU) on zinc amended and unamended media. Transient peaks in glucose respiration rates mg-' protein and AFDW occurred within 5 to 10 days in streams dosed with 1.0 mg Zn 1-' and coincided with decreases in AFDW, protein, carbohydrate, Chl a, and pheo a. Respiration of glutamate did not show a significant response to dosing (a = 0.05). Epilithic plate counts demonstrated more total and zinc-tolerant CFU in dosed than in control epilithon after 20 days. After 30 days, greater biomass and lower protein: carbohydrate ratios were evident in epilithon dosed with 1.0 mg Zn 1-' compared to unamended treatments. Peaks in glucose respiration suggested the presence of zinc-tolerant heterotrophs transiently capable of increased respiration of glucose but not glutamate. Concurrently, minimal but measurable biomass inferred the persistence of zinc-tolerant microorganisms in zinc-dosed epilithon. By the end of the studies, results indicated that metal-tolerant populations replaced metal-sensitive organisms under conditions of elevated zinc concentration. These zinc adapted communities had lower potential value as a food source to grazers (low protein: carbohydrate ratio) and were no longer distinctive with respect to glucose respiration.

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Distribution of zinc-tolerant bacteria in stream sediments

Cited by 16 publications

References 12 publications

Induced Metal Tolerance in Microbenthic Communities from Three Lowland Rivers with Different Metal Loads

Induced Metal Tolerance in Microbenthic Communities from Three Lowland Rivers with Different Metal Loads

Toxicity of Zinc to Heterotrophic Bacteria From a Tropical River Sediment

Evidence of structural and functional adaptation in epilithon exposed to zinc

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