# Neutralization of Toxic Malodorous Gases from Cattle Slurry
## 1 Introduction
They facilitate the cycling of nutrients, as well as the bioremediation and decomposition of metabolic waste products [34; 35; 36]. The _Pseudomonas_ genus has useful applications in agriculture, primarily due to its active role in promoting plant growth. It can also be used in the biocontrol of crop plants. These bacteria exhibit a diverse spectrum of antagonistic traits, e.g., antagonism against \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{3}{*}{**Chemical Concentration (ppm)**} & \multicolumn{3}{c}{**Odor Intensity (Degree)**} & \multicolumn{3}{c}{**Excessively Strong**} \\ \cline{2-10}  & **None Threshold** & \multicolumn{3}{c}{**Moderate**} & \multicolumn{3}{c}{**Strong**} & \multicolumn{3}{c}{**Very Strong**} & \multicolumn{3}{c}{**Excessively Strong**} \\ \cline{2-10}  & **0** & **1** & **1.5** & **2** & **2.5** & **3** & **3.5** & **4** & **4.5** & **5** \\ \hline NH\({}_{3}\) & \textless{}0.15 & 0.15 & 0.30 & 0.59 & 0.85 & 2.35 & 4.68 & 9.33 & 18.62 & 37.1 \\ H\({}_{2}\)S & \textless{}0.0005 & 0.0005 & 0.0017 & 0.0056 & 0.019 & 0.063 & 0.21 & 0.72 & 2.39 & 8.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The olfactory thresholds for ammonia and hydrogen sulfide depending on the concentration level [11]. phytopathogenic fungi, and also plant-beneficial traits, e.g., siderophores production, and phytohormones synthesis [37]. The literature reports that the use of microbial preparation results in high removal efficiency of malodorous gases. The use of biopreparation in the form of a microcapsule, containing strains such as _Pseudomonas fluorescens_, _Enterococcus fecium_, _Bacillus subtilis_, _Bacillus megaterium_, _Leuconostoc mesenteroides_, and _Lactobacillus plantarum_ was effective in reducing ammonia by 93%, while the concentration of hydrogen sulfide was reduced by 52%, compared to the control from poultry manure [7]. Other studies [38; 39] also show that the use of microbial preparations can reduce the emission of unpleasant-smelling gases from pig manure. [PERSON] et al. [40] reported that a microbial consortium consisting of _Bacillus subtilis_, _Bacillus cereus_, and _Schizophthlum commune_ in a biological filter (BTF) removed 92.43% of NH\({}_{3}\) and 92.75% of H\({}_{2}\)S. In turn, [PERSON] et al. [41] reported that more than 98% of the ammonia could be removed using the strain of _Lactobacillus plantarum_ from piggery mud samples after 50 h of incubation. The selection of effective deodorization microbes is the most important factor in the biological method of reduction of malodorous gases. In previous studies [42], twenty-seven microbial strains were isolated from the natural environments and examined for their morphological and biological properties using the MALDI-TOF MS and 16S rRNA sequencing methods. The most frequently isolated genera among all samples were _Bacillus_, _Lactobacillus_, and _Pseudomonas_. Their lipolytic, proteolytic, amylolytic, cellulolytic, and chitinolytic activities were studied. We hypothesized that the application of a bacterial biopreparation can reduce the emission of malodorous compounds from cattle slurry while simultaneously enhancing its fertilizing properties. The effectiveness of this process will be influenced by the specific microbial strains and their synergistic interactions within the consortium. The aim of the work was to determine the ability of selected microorganisms to remove ammonia and hydrogen sulfide from slurry. Among the isolated bacterial strains, those with the highest activity and capacity for malodorous gas removal were selected. The bacteria were used in experiments both individually and as a bacterial consortium. The innovative aspect of our study is the assessment of biopreparation application to slurry, not only with regard to the reduction of NH\({}_{3}\) and H\({}_{2}\)S emissions but also in terms of enhancing the chemical composition of slurry (CS) and increasing its fertilizing potential.