Fungal pathogens associated with twig canker of shrub species in Tunisia: Considering the effect of the factors correlated

Decline phenomena of shrub species such as Quercus coccifera and Retama raetam have occurred throughout Tunisian forests since 2012. These evergreen shrubs have long been regarded for their medicinal and ecological interests. Therefore, their preservation as valuable forest resources is of great interest. However, information regarding aetiology of this disease is still scarce. Hence, the aim of this study was to identify and characterize the causal agents associated with disease symptoms in two Tunisian forests. Thirty-eight isolates were obtained from symptomatic Q. coccifera and R. raetam twigs. Morphological characterization and phylogenetic analysis of the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene cluster and partial sequence of the translation elongation factor 1-alpha gene (tef1-α) allowed the identification of three Diplodia species namely Diplodia africana, D. seriata and D. pseudoseriata. Our findings revealed that the incidence of Diplodia species was significantly correlated to the altitude, the temperature and the rainfall. Pathogenicity test showed that all Diplodia isolates are pathogenic. However, D. africana revealed to be the most aggressive species toward R. raetam. These findings were the first record of D. seriata as fungal pathogen associated with Q. coccifera dieback and D. pseudoseriata and D. africana on R. raetam in Tunisia.     

Golden Grey Mullet (Liza aurata) Alkaline Proteases: Biochemical Characterization,Application in the Shrimp Wastes Deproteinization,Laundry Commercial Detergents,and Preparation of Antioxidant Protein Hydrolysate

Digestive alkaline proteinases from golden grey mullet (Liza aurata) were extracted and characterized. The crude alkaline protease showed optimum activity at pH 8.0 and 60°C, and it was highly stable over a wide range of pH from 4.0 to 10.0, retaining more than 80% activity after incubation for 1 h at 4°C. The alkaline proteases showed extreme stability toward nonionic and anionic surfactants after preincubation for 1 h at 25°C and relative stability toward oxidizing agents. Additionally, the crude enzyme showed excellent stability and compatibility with various solid and liquid detergents. Further, proteases from golden grey mullet viscera were found to be effective in the deproteinization of shrimp wastes. The protein removal after 3 h at 45°C with an enzyme/substrate (E/S) ratio of 10 U/mg protein was about 76%. The golden grey mullet proteases were also shown to be efficient in the production of antioxidant protein hydrolysate.     

Occurrence of Biscogniauxia mediterranea in cork oak stands in Tunisia

Phytoparasitica - Cork oak decline and mortality are increasingly prevalent in the Mediterranean basin. This require particular attention due to the great economic value of this plant species....