Sami Ben Hadj Ahmed

Background: Plant-growth-promoting rhizobacteria (PGPR) are a class of beneficial bacteria that colonise the roots of plants and improve projected plant growth through a multivariate process. PGPR application is increasing steadily in the field of agriculture, providing an attractive mechanism to replace pesticides, chemical fertilisers and additional supplements. Methods: In this study, PGPR from rhizospheric soil collected from Abha, a city located in the southern region of the Kingdom of Saudi Arabia (KSA), were isolated and characterised to facilitate verifying the efficacy of using PGPR as a biological control to improve fava bean growth. Four bacterial isolates from the nodules of fava bean plants, S4, S5, S6 and S17, were isolated and characterised. Consequently, an investigation highlighting the impact of PGPR isolates on the preservation of fava bean plants from the root-knot nematode was conducted through a pot culture experiment. Soil infested with the nematode was added to the pots. Two commercial types of fava bean plants (Vicia faba L.) were co-inoculated with PGPR 15 days after planting. Result: The results reveal that the nodule-forming bacteria interact synergistically; this was evidenced by a prominent increase in the shoot length and dry weight of the fava bean plants that had been cultivated in the nematode-infested soil. The results also demonstrate that the overall treatment of the plants did not lead to nodule formation. The results indicate that nodule-forming bacteria could be utilised in leguminous crops to facilitate biocontrol of the root-knot nematode.

Anthroponotic cutaneous leishmaniais (ACL) and zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania tropica and Leishmania major, respectively, are endemic vector-borne diseases in southern Saudi Arabia. In 2021, an outbreak of cutaneous leishmaniasis occurred in the province of Asir. The main objective of our investigation was to analyze the epidemiological features of CL in southern Saudi Arabia. The ministry of health recorded 194 CL patients between January and December 2021 from the Asir province. Our findings showed that the majority of CL patients (87.1%) originated from the governorates of Khamis-Mushait and Abha. Most of the patients were males (62.3%). While CL affected all age groups, those under 13 years old were the most affected (38.1%). For both genders, CL patients were mostly Saudi citizens (90.7%) compared to non-Saudi expatriates. The majority of CL patients (75.2%) suffered from a single lesion, and the majority of lesions (61.3%) were located on the face. The seasonal prevalence of CL showed two peaks, a small one in July–August and a larger one in March. Of a total of 194 Giemsa slides samples, 188 showed positive amplification of Leishmania ITS1 gene. Based on PCR-RFLP and PCR-HMR, 183 patients showed positive amplification of L. tropica and five patients showed positive amplification of L. major. Phylogenetic analysis revealed a clear distinct separation between L. major and L. tropica sequences. Our results provided strong evidence of the pre-domination of L. tropica, the main etiological agent of ACL in Asir province. We reported for the first time the presence of L. major, an etiological agent of ZCL in the study areas. The co-circulation of ACL and ZCL highlighted the complexity of the epidemiology of CL in southern Saudi Arabia, and subsequently, further studies to identify competent vectors and reservoir hosts for the establishment of control strategies are needed.