Microbially induced calcite precipitation (MICP) has not only helped to shape our planet’s geological features but is also a promising technology to address environmental concerns in civil engineering applications. However, limited understanding of the biomineralization capacity of environmental bacteria impedes application. We therefore surveyed the environment for different mechanisms of precipitation across bacteria. The most fundamental difference was in ureolytic ability, where urease-positive bacteria caused rapid, widespread increases in pH, whereas nonureolytic strains produced such changes slowly and locally. These pH shifts correlated well with patterns of precipitation on solid medium. Strikingly, while both mechanisms led to high levels of precipitation, we observed clear differences in the precipitate. Ureolytic bacteria produced homogenous, inorganic fine crystals, whereas the crystals of nonureolytic strains were larger and had a mixed organic/inorganic composition. When representative strains were tested in application for crack healing in cement mortars, nonureolytic bacteria gave robust results, while ureolytic strains showed more variation. This may be explained by our observation that urease activity differed between growth conditions or by the different natures and therefore different material performances of the precipitates. Our results shed light on the breadth of biomineralization activity among environmental bacteria, an important step toward the rational design of bacterially based engineering solutions. IMPORTANCE Biomineralization triggered by bacteria is important in the natural environment and has many applications in industry and in civil and geotechnical engineering. The diversity in biomineralization capabilities of environmental bacteria is, however, not well understood. This study surveyed environmental bacteria for their ability to precipitate calcium carbonate minerals and investigated both the mechanisms and the resulting crystals. We show that while urease activity leads to the fastest precipitation, it is by no means essential. Importantly, the same quantities of calcium carbonate are produced by nonureolytic bacteria, and the resulting crystals appear to have larger volumes and more organic components, which are likely beneficial in specific applications. Testing both precipitation mechanisms in a self-healing concrete application showed that nonureolytic bacteria delivered more robust results. Here, we performed a systematic study of the fundamental differences in biomineralization between environmental bacteria, and we provide important information for the design of bacterially based engineering solutions.

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Small shrimp (Acetes japonicus) is a common ingredient in various dried and fermented dishes on Asian countries. In this study, we explored the nutritional qualities of small shrimps with respect to their body length. The shrimp materials were harvested from near-shore waters of Ben Tre province, Vietnam. Various measures including mineral, lipid, salt and astaxanthin content of small shrimps of three size groups including small, medium, and large were evaluated. Current results indicate high salt content of small, medium, and large shrimp, at 23.74 ± 0.01, 24.09 ± 0.01, and 27.97 ± 1.38 mg/g dry basis, respectively. The mineral content seemed to be irrelevant to body size. Large and medium shrimps showed higher lipid content than the small counterpart. However, small shrimps are advantageous in terms of astaxanthin content. Further studies should contemplate nutritional quality with respect to harvest area and dietary scheme.