# Basic Bioelement Contents in Anaerobic Intestinal Sulfate-Reducing Bacteria
## 4 Discussion
It was found that SRB can reduce metals enzymatically or through sulfate reduction with the formation of H\({}_{2}\)S, and therefore, low concentrations of heavy metals, such as Cr (VI), Hg (II), and Zn (II), enhanced the growth and sulfate-reducing activity of SRB [68, 69]. [PERSON] and [PERSON] first showed that SRB grow by oxidizing organic matter and reducing Cr (VI) to Cr (III), Mn (IV) to Mn (II), Fe (III) to Fe (II), and U (VI) to U (IV), and demonstrated that the reduction of Cr (VI) supports growth [67]. Our study of the mechanisms involved in the reduction of metals might be relevant for understanding how trace metals are reduced, whether there is a hierarchical advantage of the electron acceptor, and how cells become tolerant to toxic metals. Studies that deal with SRB presence in the intestines and correlation about the prevalence of IBD and H\({}_{2}\)S are very important since H\({}_{2}\)S-releasing compounds can be regarded as therapeutic agents [70]. H\({}_{2}\)S was also confirmed to be an important cardiovascular as well as nervous system signaling factor. Through the conversion to thiosulfate, the cecal mucosa protects itself from toxic effects of H\({}_{2}\)S [71, 72]. The results obtained by us using PCA allowed us to determine the load on the distribution of SRB strains by elemental composition. The sum of the total variation was 67.3%. The use of PCA has been shown to be effective in a number of clinical and environmental studies [43, 44, 72]. As a result of applying the principal components method for processing an array of medical data on the content of a number of chemical elements in human biological substrates for people living and working in the study area, it was shown that certain patient groups are visually identified using the billing graphs, which have different indicators for health reasons. Moreover, it was proven that by varying the components, the similarities or differences between patients can be identified, which depend on the concentration in the blood or hair of certain chemical elements. The application of PCA allows us to conclude the microelement state of the human body (\"microelementoses\"--a concept that understands \"states of deficiency, excess or imbalance of macro-micronutrients that naturally affect human health\"--introduced in an earlier study [44]). Environmental studies also applied PCA. In the research by [PERSON] (2016) [43], to analyze the relationships between the number of microorganisms of various ecological and trophic groups of the sulfidogenic community and some environmental parameters of their environment, a PCA was carried out. For the analyzed system with 12 variables, 5 main variables were identified by the values of the explained variance components, explaining up to 76% of the variations. The first main component (PC1), which includes such variables as the number of iron-reducing and ammonifying bacteria, explained up to 21.5% of the variations. The second main component (PC2) explained 18.5% of the variations and contains variables such as pH and the amount of nitrogen-fixing and denitrifying bacteria. The third component (PC3) explains up to 14.1% of the variations; the load on it is carried out by the temperature factor and the content of soluble sulfates. The number of SRB accounts for up to 11.4% of the variations (component PC4). The exception was the variable \"number of SRB,\" for which the load on PC4 was 0.72, and therefore, it might be possible that these bacteria exhibit a key role in the sulfidogenic community [43]. In the work by [PERSON] (2003) [48], five diluted soda lakes in eastern Austria and factors of abundance of heterotrophic bacteria, their production, and their controlling factors were investigated. In these ecosystems, the environmental factors, which are responsible for the control of the microbial community in the shallow soda pools, were investigated during an annual cycle. Through PCA, two factors were extracted, which explained up to 62.5% of the total variation of the ecosystems.