Endophytes and rhizospheric microorganisms support invasive species’ adaptation to environmental stresses. Here, we review the impacts of endophytes, rhizospheric microbes (particularly symbiotic nitrogen-fixers), mycorrhiza and pathogens on plant invasion in arid and semi-arid areas. Endophytes and soil microorganisms either enhance nutrient acquisition for enhancing the invasive plant immune system and/or negatively affect native plants. In addition, the positive feedback between mycorrhizal fungi and invasive plants enhances the competitive ability of the aliens, providing them more opportunities for success, establishment, and dominance. The microbes and their secondary metabolites promote invasive plant species by changing soil microbial community structure and carbon biomass as well as enzyme activity, which improves soil properties and processes. The negative impact of invasive exotic plants on the associated biota and the role of allelochemicals are also discussed. It could be concluded that endophytes interact with rhizosphere microbes to promote invasive plant species in arid and semi-arid areas in a way similar to what happens in other ecosystems; the differences are in the pathways and reactions, which depend upon the prevailing abiotic factors. More interdisciplinary field experiments integrating microbial, biotechnological, and molecular approaches are needed to understand the role of symbiotic microbes in invasion biology.

Pseudomonas aeruginosa  was used to synthesize anisotropic gold nanoparticles from the unusually reducible aryldiazonium gold (III) salt of the chemical formula [HOOC-4-C ₆ H ₄ N≡N]AuCl ₄ (abbreviated as DS-AuCl ₄ ). We investigated the effect of bacterial cell density, temperature, and pH on the AuNP synthesis. The bacterial cell density of 6.0 × 10 ⁸ CFU/mL successfully reduced 0.5 mM DS-AuCl ₄ salt to AuNPs after incubation at 37 °C (24 h), 42 °C (24 h), and 25 °C (48 h). Transmission electron microscopy (TEM) images revealed the formation of spherical, triangle, star, hexagon, and truncated triangular morphologies for the AuNPs synthesized using P. aeruginosa bacteria. The average size of AuNPs synthesized at 25 °C (48 h), 37 °C (24 h), and 42 °C (24 h) was 39.0 ± 9.1 nm, 26.0 ± 8.1 nm, and 36.7 ± 7.7 nm, respectively. The average size of AuNPs synthesized at pH 3.7, 7.0, and 12.7 was 36.7 ± 7.7 nm, 14.7 ± 3.8 nm, and 7.3 ± 2.5 nm, respectively, with the average size decreasing at a pH of 12.7. The reduction of the DS-AuCl ₄ salt was confirmed using X-ray photoelectron spectroscopy (XPS). The significant peaks for C1s, Au4f doublet, N1s, and O1s are centered at 285, 84–88, 400, and 532 eV. The ability of inactivated bacteria (autoclave-dead and mechanically lysed bacteria), peptidoglycan, and lipopolysaccharides to reduce the DS-AuCl ₄ salt to AuNPs was also investigated. Anisotropic AuNPs were synthesized using inactivated bacteria and peptidoglycan but not using lipopolysaccharides. The AuNPs demonstrated biocompatibility with human RBCs and were safe, with no antibacterial activities against Escherichia coli and Staphylococcus aureus . This is the first report demonstrating the synthesis of AuNPs using aryldiazonium gold(III) salts with P. aeruginosa . These AuNPs are promising candidates for exploring potential applications in nanomedicine and drug delivery. Key points: • Anisotropic AuNPs were synthesized using P. aeruginosa bacteria. • Dead and lysed bacterial residues synthesized anisotropic AuNPs. • AuNPs are hemocompatible. Graphical

One strategy for combating antimicrobial resistance in many infections is to combine antibacterial compounds to create combinations that outperform each molecule alone. In this study, we examine and study the inhibitory effect of combining two drugs belonging to different antibiotic classes to obtain a possible potentiating effect against some Enterobacteriaceae isolates harbouring integrons recovered from rivers and effluents of hospital and wastewater treatment plants in Eastern Cape Province, South Africa. These integrons could easily enable the isolates to acquire genes that confer additional resistance against conventional antibiotics. The minimum inhibitory concentration of the various antibiotics was determined using the broth microdilution, while the checkerboard method was used to determine the fractional inhibitory concentration indices (FICIs). A total of 26.3% (10/38) of the interactions were categorised as synergistic, while 73.7% (28/38) were indifferent. None of the combinations were antagonistic. The time–kill assays revealed all the synergistic interactions as bactericidal. Therefore, the combinations of gentamicin with tetracycline, ciprofloxacin, and ceftazidime against multidrug-resistant (MDR) Klebsiella pneumoniae, tetracycline–ceftazidime combination against MDR Escherichia coli, colistin combinations with ceftazidime and gentamicin, and tetracycline–gentamicin combinations against MDR Citrobacter freundii may be future therapeutic alternatives. Hence, the synergistic combinations reported in this study must be assessed further in vivo before their clinical applications.

The potential of sunlight photolysis in remediation of pesticide-polluted soils in Sudan is reported. The common pollutants endosulfan (alpha- and beta- isomers) and pendimethalin were exposed to sunlight over glass and soil surfaces and the periodically drawn samples were analyzed by GC-ECD and GC-MS. Photo-degradation followed biphasic model. The half-lives of direct photolysis of the two pesticides over glass and soil surfaces ranged between 1.840-6.720 d and 2.711 to 9.760 d respectively. The respective values for indirect photolysis of the two pesticides with ß-carotene over glass surface were 0.846-1.605 d and for benzophenone 1.050-1.626 d. Values for soil ß-carotene sensitized photolysis of the two pesticides were 2.260-3.158 d while the corresponding values for benzophenone sensitized photolysis on soil were 1.193-2.880 d. Meteorological factors did not show significant impact on photolysis rates. Despite the significant decrease in starting material in direct no photoproducts were detected. However, many photoproducts were detected on the indirect sets. Photo-degradation efficiency can be arranged in the order benzophenone > ß-carotene > direct exposure.

Laboratory experiments were conducted to investigate the effects of NPK fertilizer, soil type (silty clay and sandy loam) with no history of pesticide application, temperature (28 and 40 °C), and maize residue on the half-life of atrazine herbicide. NPK fertilizer was applied at 375 mg N, 187.5 mg P, and 187.5 mg K per 600 g soil, while maize straw was added at a rate of 12 g per 600 g soil. Atrazine was applied at four concentrations: 0.0678, 1.69, 3.39, and 5.08 mg g⁻¹ soil. The residual concentration of atrazine was measured using gas chromatography over a 150-day period. The results showed that atrazine degradation was highest in Algeraif soil at 40 °C (87%), followed by Algeraif soil at 28 °C (68%) and Gerif soil at 28 °C (54.2%). The addition of NPK and maize straw significantly enhanced atrazine degradation, with degradation reaching 97% at a concentration of 0.0678 mg g⁻¹ soil after 150 days. The lowest half-lives, compared to the control, were 125, 39, 25, 19, and 14 days in Gerif soil (28 °C), Algeraif soil (28 °C), Algeraif soil (40 °C), NPK, and maize straw, respectively, at an atrazine concentration of 5.08 mg g⁻¹ soil. In conclusion, the addition of NPK fertilizer and maize straw significantly enhanced atrazine degradation, reducing both its concentration and half-life in soil.

Association of the antibiotic activity of the soil Streptomyces isolates to their genetic profiles analyzed through RAPD-PCR fingerprints prompted us here in this study to use the most common bands as specific markers to identify homologous proteins within these isolates by cloning, sequencing, and characterizing these markers. Six out of twelve DNA bands ranged between 600 and 1350 bp previously obtained by RAPD-PCR analysis were purified out of the RAPD gels, and then cloned into pGEM-T Easy vector system. Success of the cloning process was confirmed by digesting purified plasmids with EcoRI. The clones namely No. 54, 55, 20, 56, 57, and 58 were sequenced using the DNA BigDye Terminator Sequencing System utilizing the M13 primer. Results indicated that the size of the inserted sequences is 599, 566, 522, 870, 857, and 254 bp, in clones No. 54. 55, 20, 56, 57, and 58, respectively. Homologous proteins of the six cloned sequences generated by DNA blast software indicated that the highest score of protein homology was scored for clone No. 54 with 87 % homology to putative secreted pectate lyase [Streptomyces coelicolor A3(2)]. The other clones showed less homology with 77 % homology for the clones No. 55 and 56, 73 % homology for the clone No. 20, and 55 % homology for the clones No. 57 and 58. The association of homologous proteins to the reported RAPD pattern is confirmed here for the first time, and the resulting DNA cloned fragments deserve further molecular analysis.