Mehanni, M., Abd El-Aziz, S. (2019). A New Bacterial Strain Alcaligenes aquatilis MAG 1 Associated with the Mediterranean Sea Lithophaga (Bivalvia) Precipitating in Nutrient Free Medium Shell-Like Calcium Carbonate Polymorphs. test, 11(1), 111-124. doi: 10.21608/eajbsg.2019.153533
Magda M. Mehanni; Shaban H. Abd El-Aziz. "A New Bacterial Strain Alcaligenes aquatilis MAG 1 Associated with the Mediterranean Sea Lithophaga (Bivalvia) Precipitating in Nutrient Free Medium Shell-Like Calcium Carbonate Polymorphs". test, 11, 1, 2019, 111-124. doi: 10.21608/eajbsg.2019.153533
Mehanni, M., Abd El-Aziz, S. (2019). 'A New Bacterial Strain Alcaligenes aquatilis MAG 1 Associated with the Mediterranean Sea Lithophaga (Bivalvia) Precipitating in Nutrient Free Medium Shell-Like Calcium Carbonate Polymorphs', test, 11(1), pp. 111-124. doi: 10.21608/eajbsg.2019.153533
Mehanni, M., Abd El-Aziz, S. A New Bacterial Strain Alcaligenes aquatilis MAG 1 Associated with the Mediterranean Sea Lithophaga (Bivalvia) Precipitating in Nutrient Free Medium Shell-Like Calcium Carbonate Polymorphs. test, 2019; 11(1): 111-124. doi: 10.21608/eajbsg.2019.153533

A New Bacterial Strain Alcaligenes aquatilis MAG 1 Associated with the Mediterranean Sea Lithophaga (Bivalvia) Precipitating in Nutrient Free Medium Shell-Like Calcium Carbonate Polymorphs

Egyptian Academic Journal of Biological Sciences, G. Microbiology
Article 11, Volume 11, Issue 1, December 2019, Pages 111-124    PDF (541.95 K)
Document Type: Original Article
DOI: 10.21608/eajbsg.2019.153533
Authors
Magda M. Mehanni1; Shaban H. Abd El-Aziz2
1Department of Botany and Microbiology, Faculty of Science, Minia University, Minia 61519, Egypt
2Department of Zoology and Entomology, Faculty of Science, Minia University, Minia 61519, Egypt
Abstract
Mediterranean Sea Lithophaga bivalve associated bacteria and their capability in calcium carbonate polymorphs formation have been investigated in the present study. Isolated bacteria were a single strain of Gram-negative, rod-shaped, and flagellated motile cells. Phylogenetic analysis based on 16S rDNA sequences consigned the isolated bacterium to Alcaligenes aquatilis species as a distinct strain assigned as Alcaligenes aquatilis strain MAG 1. Phenotypic and biochemical characteristics of the strain recorded no acids produced from different carbohydrates under aerobic conditions except for D-mannose, amygdalin, glucose, L-rhamnose, L- arabinose and D- melibiose. Isolates showed negative results for nitrate reduction, urea degradation, sulphate reduction (H2S production) and tryptophan deaminase (TDA). Alcaligenes aquatilis strain MAG 1 precipitated in nutrient-free medium different polymorphs of anhydrous CaCO3, initially, as a mixture of aragonite and calcite, and well-organized rhombohedral calcite crystals dominated by the fourth day. Conclusively, calcium carbonate biomineralization away from any added nutrients by this new strain magnifies its role as nucleation sites and retracts the effect of bacterial metabolic pathways. Besides, various CaCO3 crystal polymorphs formed by the isolated strain advocate a potential complementary role in Lithophaga shell assembly. 
Keywords
Alcaligenes aquatilis MAG 1; Aragonite; Calcite; Mediterranean Sea; Lithophaga sp
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