Isolation, Identification, and Characterization of Phosphate-Solubilizing Bacteria from Tunisian Soils

Soil microorganisms play an important role in maintaining natural ecological balance through active participation in carbon, nitrogen, sulfur, and phosphorous cycles. Phosphate-solubilizing bacteria (PSB) are of high importance in the rhizosphere, enhancing the solubilization of inorganic phosphorus complexes into soluble forms available for plant nutrition. The investigation of this species of bacteria is of major interest in agriculture, as they can be used as biofertilizers for crops. In the present study, 28 isolates of PSB were obtained after the phosphate enrichment of soil samples from five Tunisian regions. Five PSB species were identified by 16S rRNA gene sequencing including Pseudomonas fluorescens, P. putida, and P. taiwanensis, Stenotrophomonas maltophilia, and Pantoea agglomerans. Solid and liquid Pikovskaya’s (PVK) and National Botanical Research Institute’s (NBRIP) media containing insoluble tricalcium phosphate were used for the evaluation of the phosphate solubilization ability of the bacterial isolates by two methods: visual evaluation of the solubilization zone around colonies (halo) and determination of solubilized phosphates in liquid medium by the colorimetric method of the vanado-molybdate yellow. Based on the results of the halo method, the isolate of each species that showed the higher phosphate solubilization index was selected for evaluation of phosphate solubilization by the colorimetric method. In the liquid media, the bacterial isolates showed phosphate solubilization ranging from 535.70 to 618.57 µg mL−1 in the NBRIP medium, and 374.20 to 544.28 µg mL−1 in the PVK medium, with the highest values produced by P. fluorescens. The best phosphate solubilization ability and higher reduction in broth pH, which indicates higher organic acid production, were achieved in NBRIP broth for most of the PSB. Strong correlations were observed between the average capability of PSB to solubilize phosphates and both the pH and total phosphorous content in the soil. The production of the hormone indole acetic acid (IAA), which can promote plant growth, was observed for all five PSB species. Among them, P. fluorescens obtained from the forest soil of northern Tunisia showed the highest production of IAA (50.4 ± 0.9 µg mL−1).This research was partially supported by the Smart Cities Research Center under the grant UIDB/05567/2020 funded by The Portuguese Foundation for Science and Technology (FCT—Fundação para a Ciência e a Tecnologia, Portugal). The authors wish to acknowledge the Ministry of Higher Education and Scientific Research in Tunisia, which has facilitated the work performed.info:eu-repo/semantics/publishedVersio

Epidemiology of tropical bovine theileriosis (<em>Theileria annulata</em> infection) in Tunisia: A review

This article reviews the literature on the epidemiology of tropical theileriosis in Tunisia. It is a specific parasitic disease caused by the presence and proliferation in mononuclear phagocytes, then in erythrocytes of a protozoan belonging to the family Theileridae, Theileria annulata. It is biologically transmitted by several species of ixodid ticks belonging to the genus Hyalomma. The three actors involved have a very different taxonomy causing a disease whose epidemiology is particularly complex. This infection consists of three enzootic ways: enzootic stability due to an equilibrium between the host and the parasite, (ii) low enzootic instability due to the presence of a low tick population causing clinical cases in animals aged 2 to 3 years, and (iii) high enzootic instability in which the tick population is so low that the probability of a contact between an infected tick and a susceptible host is very low. Depending on the epidemiological situation, the farms can plan adapted control programs

Prevalence and risk factors of tropical theileriosis, and sequencing of <em>Theileria annulata</em>, the causative pathogen, in Setif region (Algeria) before and after tick season

To determine the prevalence of Theileria annulata infection and the influence of some risk factors, a molecular survey was carried out in the Setif region (Alge­ria). A total of 134 cattle blood samples from 21 farms were collected twice, in April and November 2015, before and after the tick vector season. Theileria annulata molecular prevalence was 25.4% in April and and 50% in November, indicating a significant increase (p < 0.001) in the number of asymptomatic car­rier animals. The molecular prevalence was significantly higher than the preva­lence in Giemsa-stained blood smears for the two periods. In April, the Fleck­vieh breed had the lowest molecular prevalence, but this prevalence increased significantly in November (p < 0.001). The breeding type and sex had no influ­ence on T. annulata prevalence. However, the infection rate increased signifi­cantly during the tick infestation period as the walls were not roughcast and had cracks (p < 0.001). The Algerian Tams1 gene sequence was very similar to the already known Mauritanian, Tunisian and Egyptian sequences

Gonadal development in the freshwater crab Sylviocarcinus pictus (H. Milne Edwards, 1853) (Brachyura: Trichodactylidae) from the Guamá river, state of Pará, Brazil

The development stages of male and female gonads in the freshwater crab Sylviocarcinus pictus (H. Milne Eduards, 1853) were described through macroscopic and microscopic (histology) examinations. The histological description was based on 40 specimens (20 each sex). Four gonadal development stages were found for females: immature, ripening, mature and spawned. The following female cells were found: ovogonia, oocytes in initial vitellogenesis, oocytes in advanced vitellogenesis, follicular cells and post-ovulatory follicles. Three development stages were found for males: immature, maturing and mature, with the indication of: spermatogonia, spermatocytes, spermatids, spermatozoids and spermatophores. These data suggest the pattern described in the literature. Size at sexual maturity was 32.3 mm of carapace width for males and 31.5 mm for females. The gonadal stages observed macroscopically by volume and color were validated through histological analysis and proved to be useful method for the rapid identification of sexual maturity in the species. The present study offers previously unpublished data on the reproductive biology of Sylviocarcinus pictus.<br>Os estádios de desenvolvimento das gônadas de machos e fêmeas de caranguejos Sylviocarcinus pictus (H. Milne Eduards, 1853) foram descritos por meio de observações macroscópicas e microscópicas (técnica histológica). A descrição histológica foi baseada em 40 espécimes (20 de cada sexo). Foram identificados quatro estádios de desenvolvimento para as fêmeas: imaturo, em maturação, maturo e em reabsorção. As seguintes células foram encontradas: ovogônias, ovócitos em vitelogênese inicial, ovócitos em vitelogênese avançada, células foliculares e folículos pós-ovulatórios. Três estádios de desenvolvimento foram encontrados para os machos: imaturo, em maturação e maturo, com indicação de: espermatogônias, espermatócitos, espermátides, espermatozóides e espermatóforos. Tais dados sugerem o padrão descrito na literatura. O tamanho da maturidade sexual foi de 32,3 mm de largura da carapaça para machos e 31,5 mm para fêmeas. Os estádios gonadais observados macroscopicamente por meio do volume e da coloração das gônadas foram validados pela análise histológica, sendo um critério útil e ágil para a identificação da maturidade sexual para a espécie. O presente estudo oferece informações inéditas sobre a biologia reprodutiva de Sylviocarcinus pictus