Genotypic and Phenotypic Characterization of Highly Alkaline-Resistant Carnobacterium maltaromaticum V-Type ATPase from the Dairy Product Based on Comparative Genomics

Although Carnobacterium maltaromaticum derived from dairy products has been used as a lactic acid bacterium industrially, several studies have reported potential pathogenicity and disease outbreaks. Because strains derived from diseased fish and dairy products are considered potentially virulent and beneficial, respectively, their genotypic and phenotypic characteristics have attracted considerable attention. A genome-wide comparison of 30 genome sequences (13, 3, and 14 strains from diseased aquatic animals, dairy products, and processed food, respectively) was carried out. Additionally, one dairy and two nondairy strains were incubated in nutrient-rich (diluted liquid media) and nutrient-deficient environments (PBS) at pH 10 to compare their alkaline resistance in accordance with different nutritional environments by measuring their optical density and viable bacterial cell counts. Interestingly, only dairy strains carried 11 shared accessory genes, and 8 genes were strongly involved in the V-type ATPase gene cluster. Given that V-type ATPase contributes to resistance to alkaline pH and salts using proton motive force generated via sodium translocation across the membrane, C. maltaromaticum with a V-type ATPase might use nutrients in food under high pH. Indeed, the dairy strain carrying the V-type ATPase exhibited the highest alkaline resistance only in the nutrient-rich environment with significant upregulation of V-type ATPase expression. These results suggest that the gene cluster of V-type ATPase and increased alkaline resistance of dairy strains facilitate adaptation in the long-term ripening of alkaline dairy products.

The mutation of Thr315 to Asn of GH10 xylanase XynR increases the alkaliphily but decreases the alkaline resistance

XynR is a thermophilic and alkaline GH10 xylanase, identified in the culture broth of alkaliphilic and thermophilic Bacillus sp. strain TAR-1. We previously selected S92E as a thermostable variant from a site saturation mutagenesis library. Here, we attempted to select the alkaliphilic XynR variant from the library and isolated T315N. In the hydrolysis of beechwood xylan, T315N and S92E/T315N exhibited a broader bell-shaped pH-dependent activity than the wild-type XynR (WT) and S92E. The optimal pH values of T315N and S92E/T315N were 6.5–9.5 while those of WT and S92E were 6.5–8.5. On the other hand, T315N and S92E/T315N exhibited a narrower bell-shaped pH-dependence of stability: the pHs at which the activity was stable after the incubation at 37 °C for 24 h were 6.0–8.5 for T315N and S92E/T315N, but 6.0–10.0 for WT and S92E. These results indicated that the mutation of Thr315 to Asn increased the alkaliphily but decreased the alkaline resistance.

Clay-Based Products Sustainable Development: Some Applications

Clay has a low environmental impact and can develop into many different products. The research presents two different case studies. In the first, the clay is the binder of raw earth doughs in order to produce clay-bricks. We investigate the effects of natural fibrous reinforcements (rice straws and basalt fibers) in four different mixtures. From the comparison with a mix without reinforcements, it is possible to affirm that the 0.40% of basalt fibers reduce the shrinkage by about 25% and increase the compressive strength by about 30%. Future studies will focus on identifying the fibrous effects on tensile strength and elastic modulus, as well as the optimal percentage of fibers. In the second study, the clay, in form of brick powder (“cocciopesto”), gives high alkaline resistance and breathability performance, as well as rendering and color to the plaster. The latter does not have artificial additives. The plaster respects the cultural instance of the original building. The research underlines how the use of a local (and traditional) material such as clay can be a promoter of sustainability in the contemporary building sector. Future studies must investigate further possible uses of clay as well as a proper regulatory framework.

The study of the destruction of heat-resistant chamotte concrete during its sharp heating and cooling

The article investigates the destruction of heat-resistant chamotte concrete of various classes: low-cement and medium-cement with the addition of quartz sand (to increase alkaline resistance) and with the addition of metal fiber (to reduce cracking) after exposure to thermal shock. Two methods for determining the heat resistance of concrete were used, in which the destruction of the material was evaluated using ultrasound using the method of a water-cooled plate and the method of one-sided heating-cooling. Studies conducted using the method of unilateral heating-cooling, revealed the formation of macrocracks in samples of low cement concrete. This method turned out to be more sensitive when evaluating concrete destruction.

Saline–alkaline resistance analysis of rice overexpressing the CsCYP1A gene of alkaline Chlorella

Plant cyclophilin (CYP) is related to chloroplast photoprotection, redox and other growth and developmental regulatory processes and responds to stress and improves tolerance to saline–alkali stress. Besides, it exerts peptidyl-prolyl cis/trans isomerase activity to participate in protein synthesis and folding. In this study, Northern blot was used to analyse the CsCYP1A gene (a CYP gene isolated from a Chlorella species) (accession number: KY207381) of tolerant Chlorella vulgaris in soda saline–alkali soil. The result showed that the expression of the CsCYP1A gene was induced by NaHCO3, NaCl and sorbitol. Additionally, Agrobacterium tumefaciens was used to infect the callus of rice (Oryza sativa var. Longjing11) for genetic transformation. Molecular detection confirmed that transgenic seedlings overexpressing CsCYP1A were obtained by hygromycin selection. Treatment with NaCl and NaHCO3 at the five-leaf stage was performed in the seedlings, and the results showed that there were significant differences between the CsCYP1A overexpressed rice lines and non-transgenic (NT) Longjing11 in terms of plant height, fresh weight, chlorophyll content, malondialdehyde content and ascorbate peroxidase activity. The CsCYP1A overexpression rice lines had higher tolerance to NaCl and NaHCO3 than NT. The current findings indicate that CsCYP1A can enhance the tolerance of rice to saline–alkali stress possibly through its involvement in reactive oxygen scavenging pathways.

Corrosion resistance of CaO–Al2O3–SiO2 glasses used for flame spraying on concrete

Concrete components can severely suffer from corrosion during their service lifetime. To achieve higher durability, glass coatings can be applied onto the concrete surface for protection purposes. Current solutions for protection measures are either sticking thin glass panes onto the concrete or applying plastic layers using flame spraying. The aim of this work was to develop an optimised glass composition for protective layers, in order to be suitable for flame spraying on concrete. The main advantage of this process is the deposition of continuous and joint-free glass layers onto complex geometries. Dense glass layers provide a much higher corrosion resistance and lifetime compared to polymer layers. The challenge encountered by these glass coatings resides in the contact with strong acidic fluids on one side and with the alkaline concrete on the other. Therefore, a new glass appropriate for flame spraying has been developed. The composition of this glass is cheaper compared to established reference glass products while providing comparable alkaline resistance. As the acid resistance of this glass is not sufficient, in order to ensure the desired requirements of an adequate corrosion protection, a multilayer glass coating was developed, in which the first layer consists of the alkaline-resistant CaO–Al2O3–SiO2 glass and the second layer of an acid-resistant glass.