Composition of Toluene-Degrading Microbial Communities from Soil at Different Concentrations of Toluene

1999 ◽  
Vol 65 (7) ◽  
pp. 3064-3070 ◽  
Author(s):  
Casey Hubert ◽  
Yin Shen ◽  
Gerrit Voordouw
Keyword(s):  
Vapor Pressure ◽  
Microbial Communities ◽  
Ribosomal Dna ◽  
Agar Plate ◽  
Soil Samples ◽  
Vacuum Pump ◽  
Cross Hybridization ◽  
16S Ribosomal Dna ◽  
Degrading Bacteria ◽  
Derivatives Of

ABSTRACT Toluene-degrading bacteria were isolated from hydrocarbon-contaminated soil by incubating liquid enrichment cultures and agar plate cultures in desiccators in which the vapor pressure of toluene was controlled by dilution with vacuum pump oil. Incubation in desiccators equilibrated with either 100, 10, or 1% (wt/wt) toluene in vacuum pump oil and testing for genomic cross-hybridization resulted in four genomically distinct strains (standards) capable of growth on toluene (strains Cstd1, Cstd2, Cstd5, and Cstd7). The optimal toluene concentrations for growth of these standards on plating media differed considerably. Cstd1 grew best in an atmosphere equilibrated with 0.1% (wt/wt) toluene, but Cstd5 failed to grow in this atmosphere. Conversely, Cstd5 grew well in the presence of 10% (wt/wt) toluene, which inhibited growth of Cstd1. 16S ribosomal DNA sequencing and cross-hybridization analysis indicated that both Cstd1 and Cstd5 are members of the genus Pseudomonas. An analysis of the microbial communities in soil samples that were incubated with 10% (wt/wt) toluene with reverse sample genome probing indicated thatPseudomonas strain Cstd5 was the dominant community member. However, incubation of soil samples with 0.1% (wt/wt) toluene resulted in a community that was dominated by Pseudomonas strain Q7, a toluene degrader that has been described previously (Y. Shen, L. G. Stehmeier, and G. Voordouw, Appl. Environ. Microbiol. 64:637–645, 1998). Q7 was not able to grow by itself in an atmosphere equilibrated with 0.1% (wt/wt) toluene but grew efficiently in coculture with Cstd1, suggesting that toluene or metabolic derivatives of toluene were transferred from Cstd1 to Q7.

scholarly journals Emergence of Tetracycline Resistance in Helicobacter pylori: Multiple Mutational Changes in 16S Ribosomal DNA and Other Genetic Loci

2002 ◽  
Vol 46 (12) ◽  
pp. 3940-3946 ◽  
Author(s):  
Daiva Dailidiene ◽  
M. Teresita Bertoli ◽  
Jolanta Miciuleviciene ◽  
Asish K. Mukhopadhyay ◽  
Giedrius Dailide ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Ribosomal Dna ◽  
Tetracycline Resistance ◽  
Clinical Isolates ◽  
Nucleotide Substitutions ◽  
16S Ribosomal Dna ◽  
Pcr Products ◽  
Great Genetic Diversity ◽  
H Pylori ◽  
Derivatives Of

ABSTRACT Tetracycline is useful in combination therapies against the gastric pathogen Helicobacter pylori. We found 6 tetracycline-resistant (Tetr) strains among 159 clinical isolates (from El Salvador, Lithuania, and India) and obtained the following four results: (i) 5 of 6 Tetr isolates contained one or two nucleotide substitutions in one part of the primary tetracycline binding site in 16S rRNA (AGA965-967 [Escherichia coli coordinates] changed to gGA, AGc, guA, or gGc [lowercase letters are used to represent the base changes]), whereas the sixth (isolate Ind75) retained AGA965-967; (ii) PCR products containing mutant 16S ribosomal DNA (rDNA) alleles transformed recipient strains to Tetr phenotypes, but transformants containing alleles with single substitutions (gGA and AGc) were less resistant than their Tetr parents; (iii) each of 10 Tetr mutants of reference strain 26695 (in which mutations were induced with metronidazole, a mutagenic anti-H. pylori agent) contained the normal AGA965-967 sequence; and (iv) transformant derivatives of Ind75 and of one of the Tetr 26695 mutants that had acquired mutant rDNA alleles were resistant to tetracycline at levels higher than those to which either parent strain was resistant. Thus, tetracycline resistance in H. pylori results from an accumulation of changes that may affect tetracycline-ribosome affinity and/or other functions (perhaps porins or efflux pumps). We suggest that the rarity of tetracycline resistance among clinical isolates reflects this need for multiple mutations and perhaps also the deleterious effects of such mutations on fitness. Formally equivalent mutations with small but additive effects are postulated to contribute importantly to traits such as host specificity and virulence and to H. pylori's great genetic diversity.

scholarly journals Gluten-degrading bacteria: availability and applications

2021 ◽  
Author(s):  
Viia Kõiv ◽  
Tanel Tenson
Keyword(s):  
Microbial Communities ◽  
Digestive Tract ◽  
Storage Proteins ◽  
Gluten Free Diet ◽  
Natural Food ◽  
Gluten Free ◽  
Efficient Treatment ◽  
Gluten Intolerance ◽  
Degrading Bacteria ◽  
Human Digestive Tract

Abstract Gluten is a mixture of storage proteins in wheat and occurs in smaller amounts in other cereal grains. It provides favorable structure to bakery products but unfortunately causes disease conditions with increasing prevalence. In the human gastrointestinal tract, gluten is cleaved into proline and gluten rich peptides that are not degraded further. These peptides trigger immune responses that might lead to celiac disease, wheat allergy, and non-celiac gluten sensitivity. The main treatment option is a gluten-free diet. Alternatively, using enzymes or microorganisms with gluten-degrading properties might alleviate the disease. These components can be used during food production or could be introduced into the digestive tract as food supplements. In addition, natural food from the environment is known to enrich the microbial communities in gut and natural environmental microbial communities have high potential to degrade gluten. It remains to be investigated if food and environment-induced changes in the gut microbiome could contribute to the triggering of gluten-related diseases. Key points • Wheat proteins, gluten, are incompletely digested in human digestive tract leading to gluten intolerance. • The only efficient treatment of gluten intolerance is life-long gluten-free diet. • Environmental bacteria acquired together with food could be source of gluten-degrading bacteria detoxifying undigested gluten peptides.

scholarly journals Bacterial Communities Associated with Host-Adapted Populations of Pea Aphids Revealed by Deep Sequencing of 16S Ribosomal DNA

PLoS ONE ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. e0120664 ◽  
Author(s):  
Jean-Pierre Gauthier ◽  
Yannick Outreman ◽  
Lucie Mieuzet ◽  
Jean-Christophe Simon
Keyword(s):  
Deep Sequencing ◽  
Ribosomal Dna ◽  
Bacterial Communities ◽  
16S Ribosomal Dna ◽  
Pea Aphids

scholarly journals Effects of Malachite Green on the Microbiomes of Milkfish Culture Ponds

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 411
Author(s):  
Chu-Wen Yang ◽  
Yi-Tang Chang ◽  
Chi-Yen Hsieh ◽  
Bea-Ven Chang
Keyword(s):  
Infectious Diseases ◽  
Microbial Communities ◽  
Malachite Green ◽  
Fish Farming ◽  
Cyanobacterial Blooms ◽  
Anoxygenic Phototrophic Bacteria ◽  
Fish Mortality ◽  
Veterinary Drug ◽  
Degrading Bacteria ◽  
Microbial Infections

Intensive fish farming through aquaculture is vulnerable to infectious diseases that can increase fish mortality and damage the productivity of aquaculture farms. To prevent infectious diseases, malachite green (MG) has been applied as a veterinary drug for various microbial infections in aquaculture settings worldwide. However, little is known regarding the consequences of MG and MG-degrading bacteria (MGDB) on microbial communities in milkfish culture ponds (MCPs). In this study, small MCPs were used as a model system to determine the effects of MG on the microbial communities in MCPs. The addition of MG led to cyanobacterial blooms in the small MCP. The addition of MGDB could not completely reverse the effects of MG on microbial communities. Cyanobacterial blooms were not prevented. Microbial communities analyzed by next generation sequencing revealed that cyanobacterial blooms may be due to increase of nitrogen cycle (including nitrogen fixation, nitrate reduction and anammox) associated microbial communities, which raised the levels of ammonium in the water of the small MCP. The communities of anoxygenic phototrophic bacteria (beneficial for aquaculture and aquatic ecosystems) decreased after the addition of MG. The results of this investigation provide valuable insights into the effects of MG in aquaculture and the difficulties of bioremediation for aquatic environments polluted by MG.

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