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This study aims to test the toxicity of some metallic elements on Salmonella enterica strains and their power to grow and to develop a biofilm to overcome this environmental stress. From 50 selected strains of Salmonella, 70% belong to the Kentucky serotypes that is the most frequent one, followed by the other serotypes such as Amsterdam 6%, anatum 4%, derby 4% Enteritidis 4%, Zanzibar 4%, typhyrimium 2%, gallinaruim 2%, inbondaka 2% and Newport 2%. All the strains have presented the invA invasion gene involved in the virulence and Salmonella infection. Genotypic BOX-PCR analysis of these strains showed 18 profiles, with a discrimination index of 0.93. The Salmonella growth has mainly revealed that the variation of the rates of different metallic elements showed a significant influence on the Salmonella growth. The qualitative, quantitative study and biofilm tubes showed that 40% of the strains have a strong capacity to form biofilm, and the wild-type phenotypes (RDAR; rigid film; Strong), This phenotype varies according to the nature and the concentration of the metal (0.1 mM-1 mM) considered. In the presence of copper, zinc, cobalt, and chromium, the Salmonella strains showed a potent capacity to form a biofilm with a slight variation in the wild-type phenotype. However, when chromium rates increased, Salmonella loses the RDAR morphotype. Addition of mercury and cadmium in the growth medium reduced the production of Salmonella biofilm by around 14 and 15%, respectively, if compared with the control free of metals., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We investigated the 16S-23S rRNA intergenic spacer region (ISR)-PCR and the phylogenetic PCR analyses of 150 Escherichia coli isolates as tools to explore their diversity, according to their sampling origins, and their relative dominance in these sampling sources. These genetic markers are used to explore phylogenetic and genetic relationships of these 150 E. coli isolates recovered from different environmental sources (water, food, animal, human and vegetables). These isolates are tested for their biochemical pattern and later genotyped through the 16S-23S rRNA intergenic spacer PCR amplification and their polymorphism investigation of PCR-amplified 16S-23S rDNA ITS. The main results of the pattern band profile revealed one to four DNA fragments. Distributing 150 E. coli isolates according to their ITS and using RS-PCR, revealed four genotypes and four subtypes. The DNA fragment size ranged from 450 to 550 bp. DNA band patterns analysis revealed considerable genetic diversity in interspecies. Thus, the 450 and 550 bp sizes of the common bands in all E. coli isolates are highly diversified. Genotype I appeared as the most frequent with 77.3% (116 isolates), genotype II with 12% (18 isolates); genotype III with 9.7% (14 isolates), and the IV rarely occurred with 4% (2 isolates). Distributing the E. coli phylogroups showed 84 isolates (56%) of group A, 35 isolates (23.3%) of group B1, 28 isolates (18.7%) of group B2 and only three isolates (2%) of group D., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The aims of this study were (i) to compare PCP removal (100 mg L -1 ) by two bacterial consortia B 1 and B 2 in sterile wastewater (STWW) and liquid mineral medium (MSM), (ii) PCP effect in biofilm formation and antimicrobial susceptibility. PCP removal was measured by high-performance liquid chromatography (HPLC) during 168 h at 30 °C. Biofilm formation was assessed with two approaches: Congo Red Agar and Microtiter-plate. Antimicrobial susceptibility was determined by the agar disc diffusion technique. The results showed that the PCP removal for consortium B 1 and B 2 after 168 h was 70 and 97.5% in STWW; 62.2 and 85.5% in MSM, respectively. In addition, PCP addition showed an increase in biofilm development especially for B 2 consortium around 3.5 nm in 100 mg L -1 PCP. PCP added in the Muller Hinton (MH) medium and Gentamicin disc showed a clear increase in diameter of cell lysis around 2 to 4.5 cm., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aims to evaluate the effect of three surfactants on the removal of PCP (800 mg L -1 ) from Secondary Treated Wastewater (STWW) by Pseudomonas putida AJ 785569. The effect of surfactants [sodium lauryl sulfate (SDS) as anionic, Tween 80 (TW80) as non-anionic and cetyltrimethylammonium bromide (CTAB) as cationic] is tested about the three following aspects: (1) bacterial growth, (2) bacterial biofilm formation or development and (3) PCP rate removal. The results showed that strain P. putida AJ 785569 could adsorb around 30 mg L -1 and remove 600 mg L -1 of PCP within 168 h of incubation. The SDS developed the growth of bacteria and the removal of PCP. This PCP removal in mineral salt medium (MSM) is around 760 mg L -1 (95% degradation) higher than the ones registered with CTAB and TW80 with a value 506.75 (63% degradation) and 364.1 mg L -1 (45% degradation), respectively. The obtained results of chloride concentration showed an important relation with PCP removal during incubation with an important value. Monitoring the development of bacterial biofilm, in MSM medium added with PCP (100 mg L -1 ) by strain P. putida AJ 785569, showed a significant increase in the optical density value from 0.9 to 4 at λ = 595 nm, a modification of strain P. putida AJ 785569's morphotype, density and color colonies., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pentachlorophenol (PCP) is a toxic compound, which is widely used as a wood preservative product and general biocide. It is persistent in the environment and has been classified as a persistent organic pollutant to be reclaimed in many countries. Bioremediation is an emerging approach to rehabilitating areas polluted by recalcitrant xenobiotics. In the present study, we evaluated the potential of three strains of Pseudomonas (P. putida S121, P. rhizophila S211, and P. fuscovagiceae S115) as bioremediation agents in depletion and detoxification of PCP in soil microcosms. PCP removal was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum PCP removal yield (85 ± 5%) were: 500 mg/kg PCP concentration, 10 8 UFC/g soil inoculum size of each strain and 55 days incubation period. The bacterial strains, P. putida, P. rhizophila, and P. fuscovagiceae, showed good capability to tolerate and degrade PCP so that they could be successfully used in synergistic effect to treat PCP polluted soils., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Actinomycetales is an order of actinobacteria that have an important role in the decomposition of organic matter. Their abundance and distribution can reflect a good level of soil fertility as well as biological activity. In this research study, actinomycetal diversity in soil was investigated under various field treatments with biowastes. Initially, unvegetated agricultural soil plots of 4 m 2 had been annually amended with increasing rates of municipal solid waste compost (MSWC at 40, 80 and 120 t ha -1  year -1 ) and farmyard manure (FM at 40 and 120 t ha -1  year -1 ) for eight consecutive years. Control consisted of unamended soil and all treatments were distributed in four randomized complete blocks. At the end of the experimental period, total DNA was extracted from fresh topsoil samples (0-20 cm) then nested PCR-DGGE sequencing method was applied to assess the long-term effect of treatments on the diversity of actinomycetes. Analytical outcomes revealed the presence of ten actinomycetal families with Streptomycetaceae, Pseudonocardiaceae and Nocardioidaceae being the most dominant regardless to changes in experimental conditions. Besides, the long-term accumulation of both biowastes in soil affected the diversity of actinomycetal communities in different ways including contribution, stimulation or inhibition. Interestingly, soil treated with MSWC at an equivalent rate of 40 t ha -1  year -1 was likely to provide optimal growth conditions for major identified genera because it showed the highest actinomycetal diversity as compared to the rest of the treatments.