Evaluation of a long-lasting microbial larvicide against Culex quinquefasciatus and Aedes aegypti under laboratory and a semi-field trial.

BACKGROUND: Microbial larvicides containing both LysiniBacillus sphaericus and Bacillus thuringiensis svar. israelensis (Bti) insecticidal crystals can display advantages for mosquito control. This includes a broader action against larvae that are refractory to the Binary (Bin) toxin from L. sphaericus, as Bin-resistant Culex quinquefasciatus and Aedes aegypti naturally refractory larvae, which often co-habit urban areas of endemic countries for arboviruses. Our principal goal was to assess the toxicity of a combined L. sphaericus/Bti larvicide (Vectomax FG™) to Cx. quinquefasciatus (susceptible CqS and Bin-resistant CqR) and Ae. aegypti (Rocke) and to determine its persistence in the breeding sites with those larvae. METHODS: The toxicity of a combined L. sphaericus/Bti product (VectoMax FG™) to larvae was performed using bioassays, and persistence was evaluated in simulate field trials carried out under the shade, testing two label concentrations during 12 weeks. A laboratory strain SREC, established with CqS and CqR larvae, was kept during four generations to evaluate the ability of the L. sphaericus/Bti to eliminate resistant larvae. RESULTS: The L. sphaericus/Bti showed toxicity (mg/L) to larvae from all strains with a decreasing pattern for CqS (LC50 = 0.006, LC90 = 0.030), CqR (LC50 = 0.009, LC90 = 0.069), and Rocke (LC50 = 0.042, LC90 = 0.086). In a simulated field trial, the larvicide showed a persistence of 6 weeks and 8 weeks, controlling larvae from all strains in containers with 100 L of water, using 2 g or 4 g per container (100 L), respectively. The treatment of SREC larvae with L. sphaericus/Bti showed its capacity to eliminate the Bin-resistant individuals using suitable concentrations to target those larvae. CONCLUSIONS: Our results showed the high efficacy and persistence of the L. sphaericus/Bti larvicide to control Cx. quinquefasciatus and Ae. aegypti that might cohabit breeding sites. These findings demonstrated that such larvicides can be an effective tool for controlling those species in urban areas with a low potential for selecting resistance.

[Deficiency in N-acetylglucosamine transport affects the sporulation process and increases the hemolytic activity of the S-layer protein in Lysinibacillus sphaericus ASB13052]. / La deficiencia en el transporte de N-acetilglucosamina en Lysinibacillus sphaericus ASB13052 afecta el proceso de esporulación e incrementa la actividad hemolítica de su S-layer.

Lysinibacillus sphaericus is a bacterium that, along with Bacillus thuringiensis var. israelensis, is considered the best biological insecticide for controlling mosquito larvae and an eco-friendly alternative to chemical insecticides. It depends on peptidic molecules such as N-acetylglucosamine to obtain carbon sources and possesses a phosphotransferase system (PTS) for their incorporation. Some strains carry S-layer proteins, whose involvement in metal retention and larvicidal activity against disease-carrying mosquitoes has been demonstrated. Alterations in the amino sugar incorporation system could affect the protein profile and functionality. Strain ASB13052 and the isogenic mutant in the ptsH gene, which is predominant in the PTS signaling pathway, were used in this study. For the first time, the presence of N-glycosylated S-layer proteins was confirmed in both strains, with a variation in their molecular weight pattern depending on the growth phase. In the exponential phase, an S-layer protein greater than 130 kDa was found in the ptsH mutant, which was absent in the wild-type strain. The mutant strain exhibited altered and incomplete low quality sporulation processes. Hemolysis analysis, associated with larvicidal activity, showed that the ptsH mutant has higher lytic efficiency, correlating with the high molecular weight protein. The results allow us to propose the potential effects that arise as a result of the absence of amino sugar transport on hemolytic activity, S-layer isoforms, and the role of N-acetylglucosamine in larvicidal activity.

Genomic insights of Fictibacillus terranigra sp. nov., a versatile metabolic bacterium from Amazonian Dark Earths.

The Amazon rainforest, a hotspot for biodiversity, is a crucial research area for scientists seeking novel microorganisms with ecological and biotechnological significance. A key region within the Amazon rainforest is the Amazonian Dark Earths (ADE), noted for supporting diverse plant and microbial communities, and its potential as a blueprint for sustainable agriculture. This study delineates the isolation, morphological traits, carbon source utilization, and genomic features of Fictibacillus terranigra CENA-BCM004, a candidate novel species of the Fictibacillus genus isolated from ADE. The genome of Fictibacillus terranigra was sequenced, resulting in 16 assembled contigs, a total length of 4,967,627 bp, and a GC content of 43.65%. Genome annotation uncovered 3315 predicted genes, encompassing a wide range of genes linked to various metabolic pathways. Phylogenetic analysis indicated that CENA-BCM004 is a putative new species, closely affiliated with other unidentified Fictibacillus species and Bacillus sp. WQ 8-8. Moreover, this strain showcased a multifaceted metabolic profile, revealing its potential for diverse biotechnological applications. It exhibited capabilities to antagonize pathogens, metabolize multiple sugars, mineralize organic matter compounds, and solubilize several minerals. These insights substantially augment our comprehension of microbial diversity in ADE and underscore the potential of Fictibacillus terranigra as a precious resource for biotechnological endeavors. The genomic data generated from this study will serve as a foundational resource for subsequent research and exploration of the biotechnological capabilities of this newly identified species.

Purification and characterization of an alkali-organic solvent-stable laccase with dye decolorization capacity from newly isolated Lysinibacillus fusiformis W11.

A new Lysinibacillus fusiformis strain with abundant laccase activity was isolated from soil under forest rotted leaf and identified as L. fusiformis W11 based on its 16S rRNA gene sequence and physiological characteristics. The laccase LfuLac was purified and characterized. The optimum temperature and pH of LfuLac on guaiacol were 45 °C and pH 9, respectively. LfuLac kept 78%, 88%, 92%, 74%, and 47% of activity at pH 7-11, respectively, suggesting the alkali resistance of the enzyme. The effects of various metal ions on LfuLac showed that Cu2+, Mg2+, and Na+ were beneficial to laccase activity and 10 mM Cu2+ increased the activity of LfuLac to 216%. LfuLac showed about 90% activity at 5% organic solvents and more than 60% activity at 20%, indicating its resistance to organic solvents. In addition, LfuLac decolorized different kinds of dyes. This study enriched our knowledge about laccase from L. fusiformis W11 and its potential industrial applications.

Lysinibacillus spp.: an IAA-producing endospore forming-bacteria that promotes plant growth.

Lysinibacillus is a bacterial genus that has generated recent interest for its biotechnological potential in agriculture. Strains belonging to this group are recognized for their mosquitocidal and bioremediation activity. However, in recent years some reports indicate its importance as plant growth promoting rhizobacteria (PGPR). This research sought to provide evidence of the PGP activity of Lysinibacillus spp. and the role of the indole-3-acetic acid (IAA) production associated with this activity. Twelve Lysinibacillus spp. strains were evaluated under greenhouse conditions, six of which increased the biomass and root architecture of corn plants. In most cases, growth stimulation was evident at 108 CFU/mL inoculum concentration. All strains produced IAA with high variation between them (20-70 µg/mL). The bioinformatic identification of predicted genes associated with IAA production allowed the detection of the indole pyruvic acid pathway to synthesize IAA in all strains; additionally, genes for a tryptamine pathway were detected in two strains. Extracellular filtrates from all strain's cultures increased the corn coleoptile length in an IAA-similar concentration pattern, which demonstrates the filtrates had an auxin-like effect on plant tissue. Five of the six strains that previously showed PGPR activity in corn also promoted the growth of Arabidopsis thaliana (col 0). These strains induced changes in root architecture of Arabidopsis mutant plants (aux1-7/axr4-2), the partial reversion of mutant phenotype indicated the role of IAA on plant growth. This work provided solid evidence of the association of Lysinibacillus spp. IAA production with their PGP activity, which constitutes a new approach for this genus. These elements contribute to the biotechnological exploration of this bacterial genus for agricultural biotechnology.

A thermophilic chemolithoautotrophic bacterial consortium suggests a mutual relationship between bacteria in extreme oligotrophic environments.

A thermophilic, chemolithoautotrophic, and aerobic microbial consortium (termed carbonitroflex) growing in a nutrient-poor medium and an atmosphere containing N2, O2, CO2, and CO is investigated as a model to expand our understanding of extreme biological systems. Here we show that the consortium is dominated by Carbonactinospora thermoautotrophica (strain StC), followed by Sphaerobacter thermophilus, Chelatococcus spp., and Geobacillus spp. Metagenomic analysis of the consortium reveals a mutual relationship among bacteria, with C. thermoautotrophica StC exhibiting carboxydotrophy and carbon-dioxide storage capacity. C. thermoautotrophica StC, Chelatococcus spp., and S. thermophilus harbor genes encoding CO dehydrogenase and formate oxidase. No pure cultures were obtained under the original growth conditions, indicating that a tightly regulated interactive metabolism might be required for group survival and growth in this extreme oligotrophic system. The breadwinner hypothesis is proposed to explain the metabolic flux model and highlight the vital role of C. thermoautotrophica StC (the sole keystone species and primary carbon producer) in the survival of all consortium members. Our data may contribute to the investigation of complex interactions in extreme environments, exemplifying the interconnections and dependency within microbial communities.

Pelgipeptins, a Nonribosomal Lipopeptide Family, Show Larvicidal Activity against Vectors Transmitting Viruses.

Aedes aegypti and Culex quinquefasciatus are vectors of numerous diseases of worldwide public importance, such as arboviruses and filariasis. The main strategy for controlling these vectors is the use of chemicals, which can induce the appearance of resistant insects. The use of Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) with larvicidal activity against arboviral-transmitting insects has been successful in many studies. In contrast, the use and knowledge of peptides with insecticidal activity are so far scarce. In this work, 25 peptides and 5 strains of each bacterial species were prospected individually or together regarding their insecticidal activity. Initially, in vitro assays of cellular cytotoxicity of the peptides against SF21 cells of Spodoptera frugiperda were performed. The peptides Polybia-MPII and pelgipeptin caused 69 and 60% of cell mortality, respectively, at the concentration of 10 µM. Thus, they were evaluated in vivo against second-stage larvae of the two Culicidae. However, in the in vivo bioassays, only pelgipeptin showed larvicidal mortality against both larvae (LC50 6.40 µM against A. aegypti, and LC50 1.22 µM against C. quinquefasciatus). The toxin-producing bacterial strain that showed the lowest LC50 against A. aegypti was Bt S8 (LC50 = 0.71 ng/mL) and against C. quinquefasciatus, it was Ls S260 (LC50 = 2.32 ng/mL). So, the synergistic activity between the association of the bacterial toxins and pelgipeptin was evaluated. A synergic effect of pelgipeptin was observed with Ls strain S260 against C. quinquefasciatus. Our results demonstrate the possibility of synergistic or individual use of both biologically active larvicides against C. quinquefasciatus and A. aegypti.

Mpp23Aa/Xpp37Aa Insecticidal Proteins from Bacillus thuringiensis (Bacillales: Bacillaceae) Are Highly Toxic to Anthonomus grandis (Coleoptera: Curculionidae) Larvae.

The beetle Anthonomus grandis Boheman, 1843, is the main cotton pest, causing enormous losses in cotton. The breeding of genetically modified plants with A. grandis resistance is seen as an important control strategy. However, the identification of molecules with high toxicity to this insect remains a challenge. The susceptibility of A. grandis larvae to proteins (Cry1Ba, Cry7Ab, and Mpp23Aa/Xpp37Aa) from Bacillus thuringiensis Berliner, 1915, with toxicity reported against Coleopteran, has been evaluated. The ingestion of different protein concentrations (which were incorporated into an artificial diet) by the larvae was tested in the laboratory, and mortality was evaluated after one week. All Cry proteins tested exhibited higher toxicity than that the untreated artificial diet. These Cry proteins showed similar results to the control Cry1Ac, with low toxicity to A. grandis, since it killed less than 50% of larvae, even at the highest concentration applied (100 µg·g-1). Mpp/Xpp proteins provided the highest toxicity with a 0.18 µg·g-1 value for the 50% lethal concentration. Importantly, this parameter is the lowest ever reported for this insect species tested with B. thuringiensis proteins. This result highlights the potential of Mpp23Aa/Xpp37Aa for the development of a biotechnological tool aiming at the field control of A. grandis.

Culex quinquefasciatus Resistant to the Binary Toxin from Lysinibacillus sphaericus Displays a Consistent Downregulation of Pantetheinase Transcripts.

Culex quinquefasciatus resistance to the binary (Bin) toxin, the major larvicidal component from Lysinibacillus sphaericus, is associated with mutations in the cqm1 gene, encoding the Bin-toxin receptor. Downregulation of the cqm1 transcript was found in the transcriptome of larvae resistant to the L. sphaericus IAB59 strain, which produces both the Bin toxin and a second binary toxin, Cry48Aa/Cry49Aa. Here, we investigated the transcription profiles of two other mosquito colonies having Bin resistance only. These confirmed the cqm1 downregulation and identified transcripts encoding the enzyme pantetheinase as the most downregulated mRNAs in both resistant colonies. Further quantification of these transcripts reinforced their strong downregulation in Bin-resistant larvae. Multiple genes were found encoding this enzyme in Cx. quinquefasciatus and a recombinant pantetheinase was then expressed in Escherichia coli and Sf9 cells, with its presence assessed in the midgut brush border membrane of susceptible larvae. The pantetheinase was expressed as a ~70 kDa protein, potentially membrane-bound, which does not seem to be significantly targeted by glycosylation. This is the first pantetheinase characterization in mosquitoes, and its remarkable downregulation might reflect features impacted by co-selection with the Bin-resistant phenotype or potential roles in the Bin-toxin mode of action that deserve to be investigated.

Isolation and screening of chromium resistant bacteria from industrial waste for bioremediation purposes / Isolamento e triagem de bactérias resistentes ao cromo de resíduos industriais para fins de biorremediação

Chromium (VI) a highly toxic metal, a major constituent of industrial waste. It is continuously release in soil and water, causes environmental and health related issues, which is increasing public concern in developing countries like Pakistan. The basic aim of this study was isolation and screening of chromium resistant bacteria from industrial waste collected from Korangi and Lyari, Karachi (24˚52ʹ46.0ʺN 66˚59ʹ25.7ʺE and 24˚48ʹ37.5ʺN 67˚06ʹ52.6ʺE). Among total of 53 isolated strains, seven bacterial strains were selected through selective enrichment and identified on the basis of morphological and biochemical characteristics. These strains were designated as S11, S13, S17, S18, S30, S35 and S48, resistance was determined against varying concentrations of chromium (100-1500 mg/l). Two bacterial strains S35 and S48 showed maximum resistance to chromium (1600 mg/l). Bacterial strains S35 and S48 were identified through 16S rRNA sequence and showed 99% similarity to Bacillus paranthracis and Bacillus paramycoides. Furthermore, growth condition including temperature and pH were optimized for both bacterial strains, showed maximum growth at temperature 30ºC and at optimum pH 7.5 and 6.5 respectively. It is concluded that indigenous bacterial strains isolated from metal contaminated industrial effluent use their innate ability to transform toxic heavy metals to less or nontoxic form and can offer an effective tool for monitoring heavy metal contamination in the environment.(AU)

O cromo (VI), metal altamente tóxico, é um dos principais constituintes dos resíduos industriais. É liberado no solo e na água, causa problemas ambientais e de saúde de crescente preocupação pública em países em desenvolvimento como o Paquistão. O objetivo básico deste estudo foi o isolamento e a triagem de bactérias resistentes ao cromo de resíduos industriais coletados em Korangi e Lyari, Karachi (24˚5246,0”N 66˚5925,7”E e 24˚4837,5”N 67˚0652,6”E). Do total de 53 cepas isoladas, sete cepas bacterianas foram selecionadas por enriquecimento seletivo e identificadas com base em características morfológicas e bioquímicas. Essas cepas foram designadas como S11, S13, S17, S18, S30, S35 e S48, apresentaram alta resistência aos metais contra concentrações variáveis (100-1500 mg / l) de cromo. Já as cepas S35 e S48 foram identificadas por meio da sequência 16S rRNA e apresentaram 99% de similaridade com Bacillus paranthracis e Bacillus paramycoides. Além disso, as condições de crescimento incluindo temperatura e pH foram otimizadas e ambas as cepas bacterianas apresentaram crescimento máximo na temperatura de 30ºC, enquanto seu pH ótimo foi observado em 7,5 e 6,5, respectivamente. Conclui-se que o potencial de resistência dessas bactérias resistentes ao cromo pode ser efetivamente utilizado na remoção de cromo de efluentes industriais contaminados. Técnicas de base biológica usando bactérias ajudarão a fornecer métodos mais baratos e ecológicos de remoção, recuperação e desintoxicação de cromo.(AU)

Isolation and screening of chromium resistant bacteria from industrial waste for bioremediation purposes / Isolamento e triagem de bactérias resistentes ao cromo de resíduos industriais para fins de biorremediação

Chromium (VI) a highly toxic metal, a major constituent of industrial waste. It is continuously release in soil and water, causes environmental and health related issues, which is increasing public concern in developing countries like Pakistan. The basic aim of this study was isolation and screening of chromium resistant bacteria from industrial waste collected from Korangi and Lyari, Karachi (24˚52ʹ46.0ʺN 66˚59ʹ25.7ʺE and 24˚48ʹ37.5ʺN 67˚06ʹ52.6ʺE). Among total of 53 isolated strains, seven bacterial strains were selected through selective enrichment and identified on the basis of morphological and biochemical characteristics. These strains were designated as S11, S13, S17, S18, S30, S35 and S48, resistance was determined against varying concentrations of chromium (100-1500 mg/l). Two bacterial strains S35 and S48 showed maximum resistance to chromium (1600 mg/l). Bacterial strains S35 and S48 were identified through 16S rRNA sequence and showed 99% similarity to Bacillus paranthracis and Bacillus paramycoides. Furthermore, growth condition including temperature and pH were optimized for both bacterial strains, showed maximum growth at temperature 30ºC and at optimum pH 7.5 and 6.5 respectively. It is concluded that indigenous bacterial strains isolated from metal contaminated industrial effluent use their innate ability to transform toxic heavy metals to less or nontoxic form and can offer an effective tool for monitoring heavy metal contamination in the environment.

O cromo (VI), metal altamente tóxico, é um dos principais constituintes dos resíduos industriais. É liberado no solo e na água, causa problemas ambientais e de saúde de crescente preocupação pública em países em desenvolvimento como o Paquistão. O objetivo básico deste estudo foi o isolamento e a triagem de bactérias resistentes ao cromo de resíduos industriais coletados em Korangi e Lyari, Karachi (24˚52’46,0”N 66˚59’25,7”E e 24˚48’37,5”N 67˚06’52,6”E). Do total de 53 cepas isoladas, sete cepas bacterianas foram selecionadas por enriquecimento seletivo e identificadas com base em características morfológicas e bioquímicas. Essas cepas foram designadas como S11, S13, S17, S18, S30, S35 e S48, apresentaram alta resistência aos metais contra concentrações variáveis (100-1500 mg / l) de cromo. Já as cepas S35 e S48 foram identificadas por meio da sequência 16S rRNA e apresentaram 99% de similaridade com Bacillus paranthracis e Bacillus paramycoides. Além disso, as condições de crescimento incluindo temperatura e pH foram otimizadas e ambas as cepas bacterianas apresentaram crescimento máximo na temperatura de 30ºC, enquanto seu pH ótimo foi observado em 7,5 e 6,5, respectivamente. Conclui-se que o potencial de resistência dessas bactérias resistentes ao cromo pode ser efetivamente utilizado na remoção de cromo de efluentes industriais contaminados. Técnicas de base biológica usando bactérias ajudarão a fornecer métodos mais baratos e ecológicos de remoção, recuperação e desintoxicação de cromo.

Chromogenicity of aerobic spore-forming bacteria of the Bacillaceae family isolated from different ecological niches and physiographic zones.

To determine the distribution patterns of pigmented bacteria of the Bacilaceae family in different physiographic zones and ecological niches, we recovered 787 isolates from 185 environmental samples (including the areas with radiation pollution). Among the strains obtained, 149 pigmented representatives were detected, which synthesized intracellular and extracellular pigments of yellow, red, pink, and dark colors. In compliance with physiological, biochemical, and chemotaxonomic features, the isolates were identified as 7 species of the Bacilaceae family. We demonstrated that the ability to synthesize pigments significantly depended on the culture medium composition. According to the color of the colonies, the absorption spectra of pigment extracts, their physicochemical properties, and the implementation of several qualitative tests, the pigmented isolates were divided into ten groups. The relative number of pigmented strains in the physiographic zone was consistent with the total level of solar radiation for the year. Most pigmented members of the Bacillaceae family were recovered from deserts and semi-deserts, and fewest of them originated from mixed forests. We show that among the studied ecological niches, pigmented strains were most often isolated from the phyllosphere and aquatic environment and least often from soils. However, the isolates from soils and aquatic environments exhibited a greater diversity of pigmentation, and a lesser variety of colored strains was obtained from the phyllosphere and the gastrointestinal tract of animals. We established that the quantitative and qualitative composition of pigmented isolates from the areas with radiation contamination differed significantly from those coming from the natural radiation background.

Thalassobacillus, a genus of extreme to moderate environmental halophiles with biotechnological potential.

Thalassobacillus is a moderately halophilic genus that has been isolated from several sites worldwide, such as hypersaline lakes, saline soils, salt flats, and volcanic mud. Halophilic bacteria have provided functional stable biomolecules in harsh conditions for industrial purposes. Despite its potential biotechnological applications, Thalassobacillus has not been fully characterized yet. This review describes the Thalassobacillus genus, with the few species reported, pointing out its possible applications in enzymes (amylases, cellulases, xylanases, and others), biosurfactants, bioactive compounds, biofuels production, bioremediation, and plant growth promotion. The Thalassobacillus genus represents a little-explored biological resource but with a high potential.

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance.

Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.

Bacillus subtilis (Bacillales, Bacillaceae) Spores Affect Survival and Population Growth in the Grain Aphid Sitobion avenae (Hemiptera, Aphididae) in Relation to the Presence of the Facultative Bacterial Endosymbiont Regiella insecticola (Enterobacteriales, Enterobacteriaceae).

The grain aphid Sitobion avenae (Fabricius) is one of the most important cereal pests, damaging crops through sap sucking and virus transmission. Sitobion avenae harbors the secondary endosymbiont Regiella insecticola, which is highly prevalent in populations in south-central Chile and other regions of the world. In order to develop ecological alternatives for biological control, we studied the effect of applying the spores of a strain of the bacterium Bacillus subtilis on the survival and fecundity of the most prevalent genotype of S. avenae in central Chile. The strain selected was one that in previous studies had shown the ability to outcompete other bacteria. Using clones of this aphid genotype infected and uninfected with R. insecticola, we found that applying B. subtilis spores through artificial diets and spraying on leaves decreased both adult survival and nymph production. The detection of spores within the aphid body was negatively correlated with nymph production and was lower in the presence of R. insecticola when applied in diets. B. subtilis spores applied on leaves reduced the number of aphids, an effect that was stronger on aphids harboring R. insecticola. A possible interaction between endosymbiotic bacteria and bacterial antagonists within the aphid body is discussed.

Reduction in concentration of chromium (VI) by Lysinibacillus macroides isolated from sediments of the Chapala Lake, Mexico.

The Chapala Lake is one of the most polluted lakes in Mexico, due to the in flow of effluents from several industrial plants, the lake accumulates pollutants such as chromium(VI) which is considered important for aquatic ecosystem. This study aimed was to evaluate the ability to decrease the concentration of chromium (VI) by Lysinibacillus macroides 2(1B)104A, isolated from sediments of the Chapala Lake. The strain was identified through 16S rRNA sequencing and phylogenetic analysis. Results showed that this strain grows in concentrations of 50, 100, 200 and 300 mgL-1 Cr(VI), in pH ranging 6 to 7, showing 79.508% reduction in concentration 50 mgL-1, determining that the reduction occurs extracellularly. Likewise, it was observed that Lysinibacillus macroides reduced the concentration of Cr(IV) in the broth, it was not observed that the bacteria could sequester Cr(VI) in the membrane or intracellularly. However, it reduced the concentration of Cr(VI) in the broth. Lysinibacillus macroides 2(1B)104A isolate showed having the ability that decrease the concentration of Cr(VI), which makes it a viable options for bioremediation of water polluted with this metal.

Molecular and biological features of Culex quinquefasciatus homozygous larvae for two cqm1 alleles that confer resistance to Lysinibacillus sphaericus larvicides.

BACKGROUND: Culex quinquefasciatus resistance to the binary toxin from Lysinibacillus sphaericus larvicides can occur because of mutations in the cqm1 gene that prevents the expression of the toxin receptor, Cqm1 α-glucosidase. In a resistant laboratory-selected colony maintained for more than 250 generations, cqm1REC and cqm1REC-2 resistance alleles were identified. The major allele initially found, cqm1REC , became minor and was replaced by cqm1REC-2 . This study aimed to investigate the features associated with homozygous larvae for each allele to understand the reasons for the allele replacement and to generate knowledge on resistance to microbial larvicides. RESULTS: Homozygous larvae for each allele were compared. Both larvae displayed the same level of resistance to the binary toxin (3500-fold); therefore, a change in phenotype was not the reason for the replacement observed. The lack of Cqm1 expression did not reduce the total specific α-glucosidase activity for homozygous cqm1REC and cqm1REC-2 larvae, which were statistically similar to the susceptible strain, using artificial or natural substrates. The expression of eight Cqm1 paralog α-glucosidases was demonstrated in resistant and susceptible larvae. Bioassays in which cqm1REC or cqm1REC-2 homozygous larvae were reared under stressful conditions showed that most adults produced were cqm1REC-2 homozygous (69%). Comparatively, in the offspring of a heterozygous sub-colony reared under optimal conditions for 20 generations, the cqm1REC allele assumed a higher frequency (0.72). CONCLUSION: Homozygous larvae for each allele exhibited a similar resistant phenotype. However, they presented specific advantages that might favor their selection and can be used in designing resistance management practices. © 2021 Society of Chemical Industry.

Mass spectrometry-based identification of bacteria isolated from industrially contaminated site in Salamanca (Mexico) and evaluation of their potential for DDT degradation.

Longstanding industrial deposits of 1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene (DDT) impose environmental threat in Salamanca city, located in central Mexico. Native bacteria from this location were isolated and identified, and their potential utility for DDT biodegradation was examined. Twenty-five isolates were obtained, and cell lysates were analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) with BiotyperTR; twenty-one organisms were identified at species level, and the other four were assigned to genus. The most abundant species corresponded to Bacillus (44%) and Pseudomonas genera (20%). Eight bacteria could grow in the presence of 200 mg/L of DDT. Two-week exposure of Lysinibacillus fusiformis, Bacillus mycoides, Bacillus pumilus, and Bacillus cereus to DDT 50 mg/L and 200 mg/L, caused percentage pesticide degradation in the range 41-48% and 26-31%, respectively. Other four bacteria presented lower degradation rates. Gas chromatography-mass spectrometry (GC-MS) analysis of the spent media revealed that eight isolates assisted the conversion of DDT, DDD (1,1-dichloro-2,2-bis-(4-chlorophenyl)ethane), and DDE (1,1-dichloro-2,2-bis-(4-chlorophenyl)ethylene) to DDMU (1,1-(2-chloro-1,1-ethenediyl)-bis-(4-chlorobenzene)); however, DDNU (2,2-bis(4-chlorophenyl)ethylene), DBP (4,4'-dichlorobenzophenone(bis(4-chlorophenyl)methanone)) and DBH (bis(4-chlorophenyl)methanol) were found only for L. fusiformis, B. mycoides, B. cereus, B. marisflavi, and B. megaterium. Within the context of DDT biodegradation, the first three were the most promising isolates and further studies will be aimed at setting the experimental conditions for efficient mineralization of DDT congeners.

Evaluation of biosurfactant production potential of Lysinibacillus fusiformis MK559526 isolated from automobile-mechanic-workshop soil.

BACKGROUND: Biosurfactants are amphipathic biological compounds with surface active potential and are produced by many microorganisms. Biosurfactant production by Lysinibacillus fusiformis MK559526 isolated from automobile-mechanic-shop soil was investigated with a view to assessing its potential for production and potential for optimization. MATERIALS AND METHODS: Effects of carbon and nitrogen sources, pH, temperature and incubation periods on biosurfactant production were evaluated with a view to optimizing the processes. Fourier Transform Infra-Red absorption peaks and Gas chromatography mass spectrometry were used to determine the functional groups of the chemical make-up and the chemical profile of the biosurfactant respectively. RESULTS: Lysinibacillus fusiformis surfactant had emulsification index of 65.15 ± 0.35 %, oil displacement of 2.7 ± 0.26 mm, zone of haemolysis of 7.3 ± 0.16 mm and a positive drop collapse test. Optimized culture conditions for biosurfactant production: temperature, 35 ºC; pH, 7.0; starch solution, 40 g/L and urea, 1.5 g/L showed a reduction in surface tension to 28.46 ± 1.11 mN/m and increased emulsification index to 93.80 ± 0.41 %. Maximum biosurfactant production of 2.92 ± 0.04 g/L was obtained after 72 h. The biosurfactant contained peptides and fatty acids. The predominant fatty acid was 9-Octadecenoic acid (80.80%). CONCLUSIONS: The above results showing high emulsification potential and remarkable reduction in the surface tension are good biosurfactant attributes. Consequently, Lysinibacillus fusiformis MK559526 is a good candidate for biosurfactant production.

Proteomic analysis and optimized production of Alkalihalobacillus patagoniensis PAT 05T extracellular proteases.

Extracellular proteolytic extracts from the haloalkalitolerant strain Alkalihalobacillus patagoniensis PAT 05T have proved highly efficient to reduce wool felting, as part of an ecofriendly treatment suitable for organic wool. In the present study, we identified the extracellular proteases produced by PAT 05T and we optimized its growth conditions for protease production through statistical methods. A total of 191 proteins were identified in PAT 05T culture supernatants through mass spectrometry analysis. Three of the 6 detected extracellular proteases belonged to the serine-endopeptidase family S8 (EC 3.4.21); two of them showed 86.3 and 67.9% identity with an alkaline protease from Bacillus alcalophilus and another one showed 50.4% identity with Bacillopeptidase F. The other 3 proteases exhibited 55.3, 49.4 and 61.1% identity with D-alanyl-D-alanine carboxypeptidase DacF, D-alanyl-D-alanine carboxypeptidase DacC and endopeptidase LytE, respectively. Using a Fractional Factorial Design followed by a Central Composite Design optimization, a twofold increase in protease production was reached. NaCl concentration was the most influential factor on protease production. The usefulness of PAT 05T extracellular proteolytic extracts to reduce wool felting was possible associated with the activity of the serine-endopeptidases closely related to highly alkaline keratinolytic proteases. The other identified proteases could cooperate, improving protein hydrolysis. This study provided valuable information for the exploitation of PAT 05T proteases which have potential for the valorization of organic wool as well as for other industrial applications.