Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria

Abstract

This work represents the first initiative to analyze the distribution of B. thuringiensis in Algeria and to evaluate the biological potential of the isolates. A total of 157 isolates were recovered, with at least one isolate in 94.4% of the samples. The highest Bt index was found in samples from rhizospheric soil (0.48) and from the Mediterranean area (0.44). Most isolates showed antifungal activity (98.5%), in contrast to the few that had antibacterial activity (29.9%). A high genetic diversity was made evident by the finding of many different crystal shapes and various combinations of shapes within a single isolate (in 58.4% of the isolates). Also, over 50% of the isolates harbored cry1, cry2, or cry9 genes, and 69.3% contained a vip3 gene. A good correlation between the presence of chitinase genes and antifungal activity was observed. More than half of the isolates with a broad spectrum of antifungal activity harbored both endochitinase and exochitinase genes. Interestingly, 15 isolates contained the two chitinase genes and all of the above cry family genes, with some of them harboring a vip3 gene as well. The combination of this large number of genes coding for entomopathogenic proteins suggests a putative wide range of entomotoxic activity.

Chitinases of Bacillus thuringiensis: Phylogeny, Modular Structure, and Applied Potentials

“…tenebrionis DSM-2803 was shown to adversely affect the growth of Colletotrichum gloeosporioides, a potent phytopathogen that causes "anthracnose" in avocado (Persea americana), and one that is responsible for significant economic loss in México (De la Fuente-Salcido et al, 2016). Other studies have also shown the adverse effect of B. thuringiensis chitinases against F. oxysporum, the etiological agent of the fungal vascular wilt of date palm, an important traditional crop in North Africa and The Middle East (Ni et al, 2015;Djenane et al, 2017). Phytopathogenic fungi alter plant physiology and cause disease throughout development, including during seed germination.…”

The promises and risks of probiotic Bacillus species

“…The probiotic species of the Bacillus genus, based on full length 16S rRNA gene sequences, prevalently belong to the subsequent phylogenetic groups (clades): Bacillus subtilis group, Bacillus pumilus group and Bacillus cereus group (Table 2) (Wattiau et al, 2001;Elshaghabee et al, 2017;Lyons & Kolter, 2017). Bacillus thuringiensis, belonging to the B. cereus group (Miller et al, 2018), is in turn a biotechnological source of parasporal Cry protein (crystal), used as an agricultural biocontrol agent with insecticide activity (Ben-Dov, 2014;Djenane et al, 2017). Other strains, often found in commercial supplements of probiotic preparations for humans or for biotechnology purposes, are B. clausii or B. coagulans.…”

Insights into the draft genome sequence of bioactives-producing Bacillus thuringiensis DNG9 isolated from Algerian soil-oil slough

“…The potential of B. thuringiensis to serve as an alternative to chemical insecticides has driven the discovery of new B. thuringiensis strains that may lead to the identification of novel protein toxins with potential use in pest management [ 1 , 6 ]. Aside from the insecticidal properties of B. thuringiensis , it has also been reported to exhibit antibacterial, antifungal, antibiofilm and emulsifying activities [ 7 , 8 ]. In general, the Bacillus species are known to be rich sources of antimicrobial compounds [ 9 – 12 ].…”

“…For B. thuringiensis , its antibacterial effects can be attributed to a wide range of compounds including bacteriocins and lipopeptides [ 13 ] . On the other hand, its antifungal activity has been attributed to the production of compounds such as zwittermycin, chitinase, and lipopeptides [ 7 ]. In this study, the whole genome sequence of B. thuringiensis DNG9 that was isolated from an oil-contaminated slough in Baraki-Algiers, Algeria was determined.…”