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A xylanolytic bacterial strain, named A59T, was isolated from a forest soil consortium in southern Argentina. Strain A59T is a Gram-stain-positive, facultative anaerobic, endospore-forming and rod-shaped bacterium. Its optimal growth conditions are 30 °C (range, 28–37 °C), pH 7 (range, pH 5–10) and it tolerates up to 7 % of NaCl (range, 2–7 %). Chemotaxonomic analysis revealed that strain A59Tpossesses meso-diaminopimelic acid in the cell wall. It contains menaquinone MK-7 as the predominant isoprenoid quinone and the major fatty acid is anteiso-C15 : 0 (35.1 %), with a moderate amount of C16 : 0 (6.9 %). According to 16S RNA gene sequence analysis, the isolate is phylogenetically placed in the same cluster as Paenibacillus taichungensis BCRC 17757T (99.7 % nucleotide sequence identity) and Paenibacillus pabuli NBRC 13638T (99.1 %) and is closely related to Paenibacillus tundrae A10bT (98.8 %). However, phylogenetic studies based on the housekeeping gyrB gene placed A59T in a separate branch from all other related type strains. Furthermore, the results of whole genome average nucleotide identity analysis (gANI) with related type strains was lower than 91.10 % and the digital DNA–DNA hybridization value was lower than 44.30 %, which are below the threshold values for separating two species. The DNA G+C content was estimated as 46.09 mol%, based on genome sequencing. On the basis of these results, A59T represents a new species of the genus Paenibacillus , and we propose the name Paenibacillus xylanivorans sp. nov. The type strain is A59T (=DSM 107920T=NCIMB 15123T).

Bacillus thuringiensis is a gram-positive and spore-forming bacterium that synthesizes a wide diversity of proteins with insecticidal activity and which has demonstrated its potential and safety as a biocontrol agent for more than four decades. However, several susceptible insect species have been reported for evolving resistance, which demands screening for strains exhibiting novel insecticidal properties. In this work, we performed the genome sequence analysis and the insecticidal characterization of B. thuringiensis strain Bt-UNVM_94 isolated from Argentina. This strain produced quasi symmetric bipyramidal parasporal crystals as shown using Scanning Electron Microscopy. Its genomic sequence harbours one coding sequence showing homology to the crystal toxin Cry7Ga2 and another, with similarity to the Mpp2Aa3 (Mtx2) toxin. Known Cry7A and Cry7B are known to be active against some coleopteran and lepidopteran larvae, respectively. However, bioassays performed with spore-crystal mixtures of strain Bt-UNVM_94 exhibited dual toxicity with 50% and 91% mortality against Cydia pomonella (Lepidoptera: Tortricidae) and Anthonomus grandis (Coleoptera: Curculionidae), respectively. No toxicity was detected against the free-living nematode Panagrellus redivivus (Rhabditidae: Panagrolaimidae). This strain also showed no PCR amplification of the type I b-exotoxin thuE gene, consistent with the absence of mortality in b-exotoxin bioassays with Musca domestica (Diptera: Muscidae). Screenings of novel B. thuringiensis strains may provide toxins with novel insecticidal properties that can be used to suppress insect resistance to the most used B. thuringiensis-crops in the field.

Phosphate-solubilizing strain INTA 293-1 from a soil sample of Corrientes province (Argentina) was identified as Bacillus thuringiensis based on its faculty to produce crystalline inclusions during sporulation and 16S rDNA sequence similarity. INTA 293-1 was found to produce bipyramidal and cuboidal crystals, containing major proteins of ca. 130 and 65 kDa respectively, resembling those present in Lepidoptera- and Diptera-active strains. Accordingly, INTA 293-1 showed insecticidal activity against lepidopteran and dipteran larvae. No insecticidal activity nor evident effects on the normal development of coleopteran larvae or nematodes were observed. Screening of cry, cyt and vip genes showed that INTA 293-1 contains cry1Ac, cry1Ia, cry2Aa, cry2Ab and vip3Aa genes. Furthermore, this new entomopathogenic strain of B. thuringiensis was able to solubilize different sources of inorganic phosphates in liquid media following similar solubilization kinetics. INTA 293-1 was effective in solubilizing hydroxyapatite, patagonic phosphate rock, and to a lesser extent the aluminium phosphate. The differential behaviour between them may be explained by differences in INTA 293-1 survival. Phosphate solubilization was associated with pH reduction. This study reveals a little-explored aspect of B. thuringiensis and paves the way for the development of new agrobiological products with multiple modes of action.

We found and characterized two cry8 genes from the Bacillus thuringiensis strain INTA Fr7-4 isolated in Argentina. These genes, cry8Kb3 and cry8Pa3, are located in a tandem array within a 13,200-bp DNA segment sequenced from a preparation of total DNA. They encode 1,169- and 1,176-amino-acid proteins, respectively. Both genes were cloned with their promoter sequences and the proteins were expressed separately in an acrystalliferous strain of B. thuringiensis leading to the formation of ovoid crystals in the recombinant strains. The toxicity against larvae of Anthonomus grandis Bh. (Coleoptera: Curculionidae) of a spore-crystal suspension from the recombinant strain containing cry8Pa3 was similar to that of the parent strain INTA Fr7-4.

Insecticidal activity of Bacillus thuringiensis is attributed largely to the crystal proteins. These were found with specific toxic activity against insects in different orders. A novel cry8 gene from B. thuringiensis strain INTA Fr7-4 from Argentina was characterized. The encoded protein, Cry8Qa2, is 1184 amino acids long and its sequence is more similar to those of Cry8F class. We cloned and expressed the protein in an acrystalliferous strain of B. thuringiensis using two differentially regulated promoters. The recombinant strains produced ovoid crystals with low toxicity against larvae of Anticarsia gemmatalis (Lepidoptera: Noctuidae). The morphology and insecticidal properties of these crystals resembled those produced by the native strain INTA Fr7-4.