Characterization of the extracellular polymeric substances (EPS) of Virgibacillus strains capable of mediating the formation of high Mg-calcite and protodolomite

Disi, Zulfa Al; Zouari, Nabil; Dittrich, Maria; Jaoua, Samir; Al-Kuwari, Hamad Al-Saad; Bontognali, Tomaso R. R.

doi:10.1016/j.marchem.2019.103693

Cited by 37 publications

(27 citation statements)

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“…Instead, we propose that in environments with low oxygen and high organic matter turnover, heterotrophic microbes become more pronounced and consume organic material creating substrates with compositions better suited to dolomite precipitation. This is corroborated by recent laboratory studies that have suggested a similar “new-way” of producing low-t dolomite in the presence of anoxygenic strains 26 , 68 , which is also in agreement with our concept of dolomite formation. Our hypothesis is soundly corroborated in modern environments and laboratory experiments, but attempting to apply this model to paleo-studies regarding low-t dolomite can allow us to evaluate its applicability over longer time scales.…”

Section: Discussionsupporting

confidence: 92%

Modern dolomite formation caused by seasonal cycling of oxygenic phototrophs and anoxygenic phototrophs in a hypersaline sabkha

Diloreto

Garg

Bontognali

et al. 2021

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The “Dolomite Problem” has been a controversy for over a century, owing to massive assemblages of low-temperature dolomite in ancient rocks with little dolomite forming today despite favorable geochemical conditions. Experiments show that microbes and their exopolymeric substances (EPS) nucleate dolomite. However, factors controlling ancient abundances of dolomite can still not be explained. To decode the enigma of ancient dolomite, we examined a modern dolomite forming environment, and found that a cyclic shift in microbial community between cyanobacteria and anoxygenic phototrophs creates EPS suited to dolomite precipitation. Specifically, EPS show an increased concentration of carboxylic functional groups as microbial composition cycles from cyanobacterial to anoxygenic phototroph driven communities at low-and high- salinity, respectively. Comparing these results to other low-T forming environments suggests that large turnover of organic material under anoxic conditions is an important driver of the process. Consequently, the shift in atmospheric oxygen throughout Earth’s history may explain important aspects of “The Dolomite Problem”. Our results provide new context for the interpretation of dolomite throughout Earth’s history.

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Section: Discussionsupporting

confidence: 92%

Modern dolomite formation caused by seasonal cycling of oxygenic phototrophs and anoxygenic phototrophs in a hypersaline sabkha

Diloreto

Garg

Bontognali

et al. 2021

Sci Rep

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“…They also explain the high diversity of their potential to form diverse minerals in sabkhas, related to their diversity of adaptation routes. Al Disi et al, (2019) 19 showed high variability of EPS compositions as a tool employed by Virgibacillus to adapt differently to stressors mainly through modulating EPS composition. This result agrees with those reported by earlier in 2015 showing that MALDI-TOF MS and PCA were appropriate to elucidate the environmental signicance of biodegradation potential of petroleum hydrocarbons by bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…[16][17][18] Virgibacillus strains from Dohat Faishakh were shown to respond differently to such stressors. 19 The compared amplied 16s rRNA sequences was insufficient to explain the diversity of Virgibacillus in biomineralization potential. However, the relationship between the possible diversity of function and diverse capacities to form minerals in terms of magnesium incorporation into the carbonate minerals is not well elucidated.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, a correlation between mineral formation, magnesium incorporation and composition of exopolymeric substances was recently reported. 19 It is now important to establish the relationship between the diversity of bacterial isolates, even at the level of species, their response to different stressors via EPS and minerals' diversity. Since the separate study of each of them in the huge bacterial population in the environment cannot be contemplated, a fast and easy prediction of such relationship through bacterial clustering is proposed in the current work.…”

Section: Introductionmentioning

confidence: 99%

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The use of principle component analysis and MALDI-TOF MS for the differentiation of mineral forming Virgibacillus and Bacillus species isolated from sabkhas

et al. 2020

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“…72 MD567.52026.59 ± 1.65MD66102038.45 ± 1.35MD463.53027.70 ± 2.00MD567.53031.63 ± 0.62MD66103041.52 ± 1.71MD463.54042.17 ± 2.02MD567.54044.43 ± 0.97MD66104046.82 ± 1.14MD7123.52035.32 ± 0.99This workMD8127.52034.44 ± 2.24MD912102040.21 ± 2.65MD7123.53038.21 ± 1.96MD8127.53040.23 ± 2.03MD912103041.52 ± 1.80MD7123.54040.01 ± 1.91MD8127.54041.41 ± 1.31MD912104044.64 ± 1.52DF2141MD463.52029.93 ± 1.38Ref. 72 MD567.52020.87 ± 1.25MD66102041.60 ± 1.06MD463.53033.34 ± 2.38MD567.53027.15 ± 1.51MD66103038.49 ± 0.82MD463.54043.25 ± 1.52MD567.54041.95 ± 1.46MD66104044.85 ± 1.29MD712…”

Section: Resultsmentioning

confidence: 99%

Influence of temperature, salinity and Mg2+:Ca2+ ratio on microbially-mediated formation of Mg-rich carbonates by Virgibacillus strains isolated from a sabkha environment

Disi¹,

Bontognali²,

Jaoua³

et al. 2019

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Studies have demonstrated that microbes facilitate the incorporation of Mg2+ into carbonate minerals, leading to the formation of potential dolomite precursors. Most microbes that are capable of mediating Mg-rich carbonates have been isolated from evaporitic environments in which temperature and salinity are higher than those of average marine environments. However, how such physicochemical factors affect and concur with microbial activity influencing mineral precipitation remains poorly constrained. Here, we report the results of laboratory precipitation experiments using two mineral-forming Virgibacillus strains and one non-mineral-forming strain of Bacillus licheniformis, all isolated from the Dohat Faishakh sabkha in Qatar. They were grown under different combinations of temperature (20°, 30°, 40 °C), salinity (3.5, 7.5, 10 NaCl %w/v), and Mg2+:Ca2+ ratios (1:1, 6:1 and 12:1). Our results show that the incorporation of Mg2+ into the carbonate minerals is significantly affected by all of the three tested factors. With a Mg2+:Ca2+ ratio of 1, no Mg-rich carbonates formed during the experiments. With a Mg2+:Ca2+ ratios of 6 and 12, multivariate analysis indicates that temperature has the highest impact followed by salinity and Mg2+:Ca2+ ratio. The outcome of this study suggests that warm and saline environments are particularly favourable for microbially mediated formation of Mg-rich carbonates and provides new insight for interpreting ancient dolomite formations.

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Characterization of the extracellular polymeric substances (EPS) of Virgibacillus strains capable of mediating the formation of high Mg-calcite and protodolomite

Cited by 37 publications

References 50 publications

Modern dolomite formation caused by seasonal cycling of oxygenic phototrophs and anoxygenic phototrophs in a hypersaline sabkha

Modern dolomite formation caused by seasonal cycling of oxygenic phototrophs and anoxygenic phototrophs in a hypersaline sabkha

The use of principle component analysis and MALDI-TOF MS for the differentiation of mineral forming Virgibacillus and Bacillus species isolated from sabkhas

Influence of temperature, salinity and Mg2+:Ca2+ ratio on microbially-mediated formation of Mg-rich carbonates by Virgibacillus strains isolated from a sabkha environment

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