Immunostimulant Activity of Bacteria Isolated from Extreme Environments in Baja California Sur, Mexico: A Bioprospecting Approach.

Excessive use of antibiotics has led to an increase of pathogenic bacteria with multiple antibiotic resistance. Hypersaline and hyperthermal environments promote the development of several microorganisms that can potentially act as immunostimulants. Thus, the aim of this study was bioprospecting marine bacteria from these environments using mouse leukocytes as a cell model for assess immunostimulatory activity. Samples were taken from two evaporation ponds with 4 and 8% salinity (p/v) in a marine solar saltern (MSS) at Laguna Ojo de Liebre, Guerrero Negro and a shallow hydrothermal vent (SHV), Bahía Concepción under a mangrove forest both off Baja California Sur, México. From total number of isolates (N = 340), 267 were obtained from the MSS and 73 from the SHV. The 10 isolates that induced nitric oxide (NO) production in mouse splenocytes were identified using the 16S rRNA gene, of which Halomonas elongata, Halomonas sp., Pseudoalteromonas ruthenica, Bacillus subtilis and three Bacillus strains were isolated from the MSS ponds at 8% salinity and three Marinobacter lutaoensis strains from the SHV. Most of the selected bacteria were not cytotoxic for mouse splenocytes and enhanced phagocytic respiratory burst and antioxidant enzyme activities compared to the control immunostimulant (lipopolysaccharide from Escherichia coli). Selected bacteria from 8% salinity ponds in the MSS in Guerrero Negro had immunostimulant activity in vitro in mouse splenocytes. In conclusion, Bacillus subtilis SA4 220, Bacillus sp. SA4 62A, P. ruthenica SA4 40 as well as Halomonas sp. SA4 207 and Halomonas elongata SA8 44 increased several immunological parameters. Further research is needed to evaluate their potential application in preclinical models to fight against infectious diseases. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-022-01002-3.

Effect of Noble Metal Addition on the Disorder Dynamics of Ni3Al by Means of Monte Carlo Simulation.

In this work, the effect of the addition of noble metals on the order-order disorder process of the L12 structure corresponding to the intermetallic Ni3Al is analyzed. Stoichiometric, nonstoichiometric, and quasi-binary compositions doped with noble metals such as Ag, Au, Pd, and Pt (1 at%) were analyzed. It was observed that depending on the composition, there is a modification in the activation energies calculated from the two time constants that characterize the disorder process. The statistic of atomic jumps was typified based on the configuration of the window to be crossed and, with this, it was identified that the origin of the negative activation energy of the long disorder process is due to an increase in the corresponding energy of the AlAl-Ni jump through unnatural windows.

Rare Earth-Based Compounds as Inhibitors of Hot-Corrosion Induced by Vanadium Salts.

In this study, the performance evaluation of lanthanum compounds as corrosion inhibitors of vanadium salts was performed. The inhibitors tested were lanthanum acetate and La2O3. The performance of the inhibitors was tested using sodium metavanadate (NaVO3) as a corrosive medium at 700, 800, and 900 °C. The corrosion inhibitory effect was evaluated on the corrosion process of 304H stainless steel. The corrosion rate of the steel was determined by the mass loss technique after 100 h of immersion in the corrosive salt with and without the addition of the corrosion inhibitor. The results show that lanthanum compounds act as corrosion inhibitors of vanadium salts. The inhibitory effect increases by increasing the concentration and tends to decrease when increasing the test temperature. Lanthanum compounds act as excellent corrosion inhibitors due to their ability to stabilize vanadium cations. Vanadium is stabilized by forming a new compound, lanthanum vanadate (LaVO4), with a melting point much higher than the compounds formed when Mg or Ni compounds are used as corrosion inhibitors.

Immunopathological evaluation of recombinant mycobacterial antigen Hsp65 expressed in Lactococcus lactis as a novel vaccine candidate.

Bovine tuberculosis (TBB) is a zoonotic disease distributed worldwide and is of great importance for public health and the livestock industry. Several experimental vaccines against this disease have been evaluated in recent years, yielding varying results. An example is the Bacillus Calmette-Guérin (BCG) vaccine, which has been used extensively in humans and tested in cattle showing mixed results related to protection (0-80%) against Mycobacterium bovis. In this study, we used the food-grade bacterium Lactococcus lactis as an expression system for production of mycobacterial protein Hsp65. For this purpose, the construction of a replicable plasmid in strain NZ9000 L. lactis (pVElepr) was conducted, which expressed the Mycobacterium leprae Hsp65 antigen, and was recognized by traded anti-Hsp65 antibodies. The strain NZ9000-pVElepr was applied to calves that were negative to tuberculin test and the immune response was monitored. The results showed that immune response was not significantly increased in calves with NZ9000-pVElepr with respect to control groups, and no injury was observed in any lung or lymph of the calves. Finally, this study suggest that the recombinant NZ9000 strain of L. lactis may protect against the development of M. bovis infection, although studies with longer exposure to this pathogen are necessary to conclude the matter.

Genome-wide identification of copy number variations in Holstein cattle from Baja California, Mexico, using high-density SNP genotyping arrays.

Copy number variations (CNVs) are an important source of genomic structural variation, and can be used as markers to investigate phenotypic and economic traits. CNVs also have functional effects on gene expression and can contribute to disease susceptibility in mammals. Currently, single nucleotide polymorphism genotyping arrays (SNP chips) are the technology of choice for identifying CNV variations. Microarray technologies have recently been used to study the bovine genome. The objective of the present study was to develop CNVs in Holstein cows from the Northwest of Mexico using the Affymetrix Axiom Genome-Wide BOS 1 Array, which assays 648,315 SNPs and provides a wide coverage for genome-wide studies. We applied the two most widely used algorithms for the discovery of CNVs (PennCNV and QuantiSNP) and found 56 CNV regions (CNVRs) representing 0.33% of the bovine genome (8.46 Mb). These CNVRs ranged from 1.5 to 970.8 kb with an average length of 151 kb. They involved 103 genes and showed a 28% overlap with CNVRs already reported. Of the 56 CNVRs found, 20 were novel. In this study we present the first genomic analysis of CNVs in Mexican cattle using high-density SNP data. Our results provide a new reference basis for future genomic variation and association studies between CNVs and phenotypes, especially in Mexican cattle.

Field evaluation of the protective efficacy of Mycobacterium bovis BCG vaccine against bovine tuberculosis.

The protective efficacy of Mycobacterium bovis BCG (1 x 10(6) single dose) was evaluated under field conditions. A total of 140 male Holstein Friesian calves, one to two week-old were selected. Two groups of 70 each were formed, one group was vaccinated and the other was injected with a placebo during their second week of age and followed until 12 months of age. The study considered a positive case of tuberculosis to be an animal that had a positive reaction to the three following tests in a row: tuberculin, IFNgamma PPD-B and IFNgamma ESAT6-CFP10 during the 12 months of exposure. The results showed a 59.4% efficacy (IC95%: 47.64-71.16). The non-vaccinated calves were 2.4 times more at risk of becoming infected (IC95%: 1.07-5.68) compared to vaccinated animals. As a complementary test a PCR test was performed using nasal exudates in some animals from both groups using a Mycobacterium complex detection kit. All the positive PCR reactions (5/44) were found in the non-vaccinated animals. These findings suggest that the use of the BCG vaccine, even though it is not capable of protecting 100%, does prevent TB vaccinated animals from excreting bacilli in their nasal secretions at their first year of age.