Study of Some Biocontrol Bacterial Isolates and Evaluation of Their Antifungal and Insecticidal Effects

The biological control of phytopathogenic diseases and other pests by the introduction of microorganisms beneficial of the rhizosphere has been proposed as an alternative to chemical control. The objective of our work is to determine the elements on which this interaction between antagonistic bacteria and bioagressors of cultures such as secondary metabolites, is based. The present work involves the identification of a collection of strains belonging to the Bacillus genus with the demonstration of the synthesis of secondary metabolites such as enzymes with hydrolytic effect and the characterization of their bioactive molecules as well as the study of their effect antagonist against Verticillium dahliae agent of the verticilliose and insecticidal effect against Galleria mellonela. These isolats are from the rhizosphere soil of three cultivated plants (Nèfle, Barley and potato) in the region of Boumerdes (North Algeria). The macroscopic and microscopic identification tests allowed us to select strains with characteristics identical to those of Bacillus sp. The study of the different enzymes (amylase, cellulase, chitinase, caseinase) show for the majority of strains a good production, which explains their efficiency against Verticillium dahliae. In fact, the biological control tests carried out in vitro by these bacterial strains have shown that it is possible to limit the incidence of V. dahliae and that the use of this biological treatment makes it possible to maintain the disease at an acceptable threshold. These strains can therefore have a role in antagonism and plant biostimulation. Concerning the insecticidal effect of bacteria on the larvae of the wax moth Galleria mellonella, very significant results are achieved with 100%25 mortality recorded 8 days after treatment at the high dose (1.10 7 ufc%252Fml). It appears that these isolates could find their place in biotechnological applications aimed at improving yields and preserving the environment for sustainable development

Phytochemical Characterization and Antimicrobial Potentialities of Two Medicinal plants, Chamaemelum nobile (L.) All and Matricaria chamomilla (L.)

Objective of the study was to evaluate the phytochemical characterization and antimicrobial effectiveness of two medicinal plants belonging to the Asteraceae family, growing spontaneously in the region of Boumerdes (Northeast Algeria) namely Chamaemelum nobile (L.) All and Matricaria chamomilla (L.). For this purpose, it was proposed to optimize the extraction parameters of the phenolic compounds of the aerial parts of two chosen species. The first step was intended to study the effect of different extraction solvents (water, chloroform and methanol) on the contents of different metabolites of these species. The qualitative screening of the aerial part of chamomile allowed to highlight different families of chemical compounds namely%253B flavonoids, total tannins, condensed tannins, gallic tannins, alkaloids, saponosides, glucosides, mucilages and total absence of anthocyanins and starch. This was confirmed by a quantitative analysis based on the determination of total phenolic compounds by spectrophotometry in the presence of the Folin-Ciocalteu reagent determined from the calibration curve of gallic acid. The results showed that the water was the best extraction solvent. At the second stage of our study, antimicrobial activity of the extracts was determined on six microbial strains such as Staphylococcus aureus, Bacillus thuringiensis, Escherichia coli and Fusarium sp., according to the disk diffusion method, and gave zones of inhibition ranging from 7 to 15 mm. Thus, the extracts had a moderately inhibitory activity and have reacted positively on at least one of the microbial strains tested with the exception of the fungal flora. However, the methanolic extract of M. chamomilla revealed a strong activity against to Pseudomonas sp. with an inhibition zone estimated at 22.5 mm

Efficacy of Toxins and Spores of a Local Rhizobacterial Strain Bacillus clausii (MT305787) against the Wax Moth Galleria mellonella

To reduce the dependence of the agricultural sector on chemical inputs, the use of biopesticides is becoming increasingly effective and advocated, the formulation of biocides based on microorganisms is a more efficient solution. Our work is based on exploiting the larvicidal potential of a bacterial strain (B8) of the genus Bacillus against the fifth instar larvae of the hive moth Galleria Mellonella. The bacterial strain used in the current study was isolated from medlar rhizosphere in the region of Boumerdes (located in the north of Algeria). 16s RNA sequencing and phylogenetic analysis affiliate it with the species Bacillus clausii

Effects of Pollen Deprivation in Groups of Tellian (Apis mellifera intermissa) and Saharan (Apis mellifera sahariensis) Honey Bees under Controlled Conditions

Worldwide, honey bees are increasingly faced with periods of pollen scarcity, which can lead to nutritional deficiencies, especially of proteins and amino acids. These are essential for the proper functioning of the single organism and the colony. To understand how bees react to protein deficiency, under controlled conditions, we studied the effect of pollen deficiency on the main physiological parameters in two subspecies endemic of Algeria, Apis mellifera intermissa and Apismellifera sahariensis. Emerging workers of both subspecies were reared with two diets: one was pollen-fed, whereas the other pollen-deprived. Several physiological criteria were measured depending on the type of diet and subspecies: the survival of the bees, the amount of total protein in the hemolymph, hypopharyngeal glands development and the ovary development of workers. These last three parameters were assessed at three different ages (7, 14 and 21 days). At birth, sahariensis workers weighed more than intermissa. With the same protein diet, the average life expectancy of sahariensis was extended by 5.55 days compared to intermissa. Even if deprived of pollen, sahariensis lived longer than intermissa fed with pollen (p < 0.001). In the three age levels, the hypopharyngeal glands were more developed and less affected by pollen deficiency (p < 0.001) in sahariensis than in intermissa (p < 0.001). The total hemolymph protein was higher in intermissa than in sahariensis regardless of the diet, and was also higher in protein-fed than in deprived bees (p < 0.001). The ovaries developed more rapidly with a high proportion in intermissa than in sahariensis (p < 0.05) regardless of the diet, and was also higher in the bees fed with pollen than those deprived (p < 0.05). Pollen deficiency generates physiological alterations and modifications, the amplitude of which varied according to the subspecies of the bee studied