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Lysinibacillus sphaericus is a spore-forming bacterium used in the biological control of mosquitoes and in bioremediation. Mosquito larvae exposed to heavy metals are tolerant to concentrations above the permissible limit for industrial residual waters. In this work, we characterize 51 L. sphaericus strains for metal tolerance and larvicidal activity against Culex quinquefasciatus. Lysinibacillus sphaericus OT4b.2, OT4b.20, OT4b.25, OT4b.26 and OT4b.58 were as toxic as the spores of the reference strain 2362 against C. quinquefasciatus larvae. 19 Mosquito-pathogenic L. sphaericus strains and 6 non-pathogenic strains were able to grow in arsenate, hexavalent chromium and/or lead. 16S rRNA gene sequences and phylogenetic analyses clustered 84 % of the metal-tolerant strains in L. sphaericus group 1, which encompasses the mosquitocidal strains. The larvicidal activity of vegetative and sporulated cells and its high tolerance to arsenate, hexavalent chromium and lead indicate that L. sphaericus OT4b.26 is a strong candidate for further studies examining its potential for biological control of mosquitoes in waters contaminated with metals.

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Lysinibacillus sphaericus strain OT4b.31 is a native Colombian strain having no larvicidal activity against Culex quinquefasciatus and is widely applied in the bioremediation of heavy-metal polluted environments. Strain OT4b.31 was placed between DNA homology groups III and IV. By gap-filling and alignment steps, we propose a 4,096,672 bp chromosomal scaffold. The whole genome (consisting of 4,856,302 bp long, 94 contigs and 4,846 predicted protein-coding sequences) revealed differences in comparison to the L. sphaericus C3-41 genome, such as syntenial relationships, prophages and putative mosquitocidal toxins. Sphaericolysin B354, the coleopteran toxin Sip1A and heavy metal resistance clusters from nik, ars, czc, cop, chr, czr and cad operons were identified. Lysinibacillus sphaericus OT4b.31 has applications not only in bioremediation efforts, but also in the biological control of agricultural pests.

Petroleum oil is a major driver of worldwide economic activity, but it has also created contamination problems during the storage and refining process. Also, unconventional resources are natural resources, which require greater than industry‐standard levels of technology or investment to exploit. In the case of unconventional hydrocarbon resources, additional technology, energy, and capital have to be applied to extract the gas or oil. Bioremediation of petroleum spill is considered of great importance due to the contaminating effects on human health and the environment. For this reason, it is important to reduce total petroleum hydrocarbons (TPH) in contaminated soil. In addition, biosurfactant production is a desirable property of hydrocarbon‐degrading microorganisms. Seven strains belonging to Lysinibacillus sphaericus and Geobacillus sp were selected to evaluate their ability to biodegrade TPH in the presence of toxic metals, their potential to produce biosurfactants, and their ability to improve the biodegradation rate. The seven bacterial strains examined in this study were able to utilize crude petroleum‐oil hydrocarbons as the sole source of carbon and energy. In addition, their ability to degrade crude oil was not affected by the presence of toxic metals such as chromium and arsenic. At the same time, the strains were able to reduce toxic metals concentration through biosorption processes. Biosurfactant production was determined using the drop‐collapsed method for all strains, and they were characterized as both anionic and cationic biosurfactants. Biosurfactants showed an increase in biodegradation efficiency both in liquid minimal salt medium and landfarming treatments. The final results in field tests showed an efficiency of 93 percent reduction in crude oil concentration by the selected consortium compared to soil without consortium. The authors propose L. sphaericus and Geobacillus sp consortium as an optimum treatment for contaminated soils. In addition, production of biosurfactants could have an application in the extraction of crude oil from unconventional hydrocarbon resources. © 2014 Wiley Periodicals, Inc.