Production of rhamnolipids and diesel oil degradation by bacteria isolated from soil contaminated by petroleum

Biosurfactants are microbial secondary metabolites. The most studied are rhamnolipids, which decrease the surface tension and have emulsifying capacity. In this study, the production of biosurfactants, with emphasis on rhamnolipids, and diesel oil degradation by 18 strains of bacteria isolated from waste landfill soil contaminated by petroleum was analyzed. Among the studied bacteria, gram‐positive endospore forming rods (39%), gram positive rods without endospores (17%), and gram‐negative rods (44%) were found. The following methods were used to test for biosurfactant production: oil spreading, emulsification, and hemolytic activity. All strains showed the ability to disperse the diesel oil, while 77% and 44% of the strains showed hemolysis and emulsification of diesel oil, respectively. Rhamnolipids production was observed in four strains that were classified on the basis of the 16S rRNA sequences as Pseudomonas aeruginosa. Only those strains showed the rhlAB gene involved in rhamnolipids synthesis, and antibacterial activity against Escherichia coli, P. aeruginosa, Staphylococcus aureus, Bacillus cereus, Erwinia carotovora, and Ralstonia solanacearum. The highest production of rhamnolipids was 565.7 mg/L observed in mineral medium containing olive oil (pH 8). With regard to the capacity to degrade diesel oil, it was observed that 7 strains were positive in reduction of the dye 2,6‐dichlorophenolindophenol (2,6‐DCPIP) while 16 had the gene alkane mono‐oxygenase (alkB), and the producers of rhamnolipids were positive in both tests. Several bacterial strains have shown high potential to be explored further for bioremediation purposes due to their simultaneous ability to emulsify, disperse, and degrade diesel oil. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:262–270, 2016     

Oligomerization,Membrane Association,and in Vivo Phosphorylation of Sugarcane UDP-glucose Pyrophosphorylase

Sugarcane is a monocot plant that accumulates sucrose to levels of up to 50% of dry weight in the stalk. The mechanisms that are involved in sucrose accumulation in sugarcane are not well understood, and little is known with regard to factors that control the extent of sucrose storage in the stalks. UDP-glucose pyrophosphorylase (UGPase; EC 2.7.7.9) is an enzyme that produces UDP-glucose, a key precursor for sucrose metabolism and cell wall biosynthesis. The objective of this work was to gain insights into the ScUGPase-1 expression pattern and regulatory mechanisms that control protein activity. ScUGPase-1 expression was negatively correlated with the sucrose content in the internodes during development, and only slight differences in the expression patterns were observed between two cultivars that differ in sucrose content. The intracellular localization of ScUGPase-1 indicated partial membrane association of this soluble protein in both the leaves and internodes. Using a phospho-specific antibody, we observed that ScUGPase-1 was phosphorylated in vivo at the Ser-419 site in the soluble and membrane fractions from the leaves but not from the internodes. The purified recombinant enzyme was kinetically characterized in the direction of UDP-glucose formation, and the enzyme activity was affected by redox modification. Preincubation with H₂O₂ strongly inhibited this activity, which could be reversed by DTT. Small angle x-ray scattering analysis indicated that the dimer interface is located at the C terminus and provided the first structural model of the dimer of sugarcane UGPase in solution.     

Alanyl-glutamine and glutamine plus alanine supplements improve skeletal redox status in trained rats: Involvement of heat shock protein pathways

Aims

We hypothesized that oral l-glutamine supplementations could attenuate muscle damage and oxidative stress, mediated by glutathione (GSH) in high-intensity aerobic exercise by increasing the 70-kDa heat shock proteins (HSP70) and heat shock factor 1 (HSF1).

Main methods

Adult male Wistar rats were 8-week trained (60-min/day, 5 days/week) on a treadmill. During the last 21 days, the animals were supplemented with either l-alanyl-l-glutamine dipeptide (1.5 g/kg, DIP) or a solution containing the amino acids l-glutamine (1 g/kg) and l-alanine (0.67 g/kg) in their free form (GLN + ALA) or water (controls).

Key findings

Plasma from both DIP- and GLN + ALA-treated animals showed higher l-glutamine concentrations and reduced ammonium, malondialdehyde, myoglobin and creatine kinase activity. In the soleus and gastrocnemius muscle of both supplemented groups, l-glutamine and GSH contents were increased and GSH disulfide (GSSG) to GSH ratio was attenuated (p < 0.001). In the soleus muscle, cytosolic and nuclear HSP70 and HSF1 were increased by DIP supplementation. GLN + ALA group exhibited higher HSP70 (only in the nucleus) and HSF1 (cytosol and nucleus). In the gastrocnemius muscle, both supplementations were able to increase cytosolic HSP70 and cytosolic and nuclear HSF1.

Significance

In trained rats, oral supplementation with DIP or GLN + ALA solution increased the expression of muscle HSP70, favored muscle l-glutamine/GSH status and improved redox defenses, which attenuate markers of muscle damage, thus improving the beneficial effects of high-intensity exercise training.     

Signatures in SARS-CoV-2 spike protein conferring escape to neutralizing antibodies

Understanding SARS-CoV-2 evolution and host immunity is critical to control COVID-19 pandemics. At the core is an arms-race between SARS-CoV-2 antibody and angiotensin-converting enzyme 2 (ACE2) recognition, a function of the viral protein spike. Mutations in spike impacting antibody and/or ACE2 binding are appearing worldwide, imposing the need to monitor SARS-CoV2 evolution and dynamics in the population. Determining signatures in SARS-CoV-2 that render the virus resistant to neutralizing antibodies is critical. We engineered 25 spike-pseudotyped lentiviruses containing individual and combined mutations in the spike protein, including all defining mutations in the variants of concern, to identify the effect of single and synergic amino acid substitutions in promoting immune escape. We confirmed that E484K evades antibody neutralization elicited by infection or vaccination, a capacity augmented when complemented by K417N and N501Y mutations. In silico analysis provided an explanation for E484K immune evasion. E484 frequently engages in interactions with antibodies but not with ACE2. Importantly, we identified a novel amino acid of concern, S494, which shares a similar pattern. Using the already circulating mutation S494P, we found that it reduces antibody neutralization of convalescent and post-immunization sera, particularly when combined with E484K and with mutations able to increase binding to ACE2, such as N501Y. Our analysis of synergic mutations provides a signature for hotspots for immune evasion and for targets of therapies, vaccines and diagnostics.     

Mycobacterial codon optimization of the gene encoding the Sm14 antigen of Schistosoma mansoni in recombinant Mycobacterium bovis Bacille Calmette-Guérin enhances protein expression but not protection against cercarial challenge in mice

A mycobacterial codon-optimized gene encoding the Sm14 antigen of Schistosoma mansoni was generated using oligonucleotide assembly. This synthetic gene enhanced approximately fourfold the protein expression level in recombinant Mycobacterium bovis Bacille Calmette-Guérin (rBCG) when compared to that obtained using the native gene in the same expression vector. Immunization of mice with rBCG expressing Sm14 via the synthetic gene induced specific cellular Th1-predominant immune responses, as determined by interferon-gamma production of Sm14-stimulated splenocytes, which were comparable to those recorded in animals immunized with an rBCG strain expressing the native gene. Administration of a single dose of the rBCG-Sm14 construct carrying the synthetic gene conferred protection against cercarial challenge in outbred Swiss mice, at a level equivalent to those provided by either a single dose of rBCG expressing the native gene or three doses of Escherichia coli-derived recombinant Sm14. Our data demonstrated that despite improving the level of antigen expression, the codon optimization strategy did not result in enhanced immunity or protection against cercarial S. mansoni challenge.     

Design, synthesis and cruzain docking of 3-(4-substituted-aryl)-1,2,4-oxadiazole-N-acylhydrazones as anti-Trypanosoma cruzi agents

Research in recent years has demonstrated that the Trypanosoma cruzi cysteine protease cruzain (TCC) is a valid chemotherapeutic target, since inhibitors of this protease affect the pathology appropriately. By exploring the N-acylhydrazones (NAH) as privileged structures usually present in antiparasitic agents, we investigated a library of 16 NAH bearing the 3-(4-substituted-aryl)-1,2,4-oxadiazole scaffold (NAH 3a–h, 4a–h). The in vitro bioactivity against epimastigote and trypomastigote forms of T. cruzi was evaluated, and some NAH under study exhibited antitrypanosomal activity at concentrations that are not toxic to mammalian cells. The series of compounds based on the 3-(4-substituted-aryl)-1,2,4-oxadiazole scaffold revealed the remarkable importance of each substituent at the phenyl’s 4-position for the inhibitory activity. Non-nitrated compounds 3a and 4e were found to be as potent as the reference drug, Benznidazole. In addition, the molecular origin of the antitrypanosomal properties for these series was investigated using docking studies of the TCC structure.     

Frequency of the major histocompatibility complex Mamu-A*01 allele in a closed breeding colony of rhesus monkey (Macaca mulatta) from Brazil

Background  Rhesus monkeys are relevant models for human diseases. The simian immunodeficiency virus (SIV) infection is an useful macaque model for assessing human immunodeficiency virus (HIV) vaccine strategies. Susceptibility and resistance to viruses have been associated with particular major histocompatibility complex (MHC) molecules. Several epitopes in the HIV structural and non-structural protein restricted by distinct MHC class I haplotypes are important targets for human cytotoxic T lymphocytes, which mediate protection against SIVmac infection. Mamu-A*01 , for example, is a MHC class I molecule of rhesus monkeys that presents a peptide from SIV gag protein.
Methods  Our study determined the frequency of Mamu-A*01 in a closed colony of rhesus monkeys from Brazil by polymerase chain reaction.
Results  A high frequency of the allele was found in the study colony.
Conclusion  This colony provides a significant source of A*01 -positive animals to investigators.     

Repeated removal of cadmium and zinc from an industrial effluent by waste biomass Sargassum sp.

Waste biomass Sargassum sp. biosorbed 100% of Cd²⁺ and 99.4% of Zn²⁺ from a 3 and 98 mg l^–1 solution (pH 4.5), respectively, at the end of four serial experiments. Of the five desorbents studied in consecutive adsorption/desorption cycles, CaCl₂ 0.05 M eluted nearly 40% of both metals and decreased the biosorption in only 8% and 17% of Cd²⁺ and Zn²⁺, respectively. Although NaOH desorbent improved the heavy metal uptake from the second cycle onwards, it did not elute metals from the pre-loaded biomass.     

Extracellular ectonucleotidases are differentially regulated in murine tissues and human polymorphonuclear leukocytes during sepsis and inflammation

Sepsis is life-threatening organ dysfunction caused by a dysregulated inflammatory and immune response to infection. Sepsis involves the combination of exaggerated inflammation and immune suppression. During systemic infection and sepsis, the liver works as a lymphoid organ with key functions in regulating the immune response. Extracellular nucleotides are considered damage-associated molecular patterns and are involved in the control of inflammation. Their levels are finely tuned by the membrane-associated ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) enzyme family. Although previous studies have addressed the role of NTPDase1 (CD39), the role of the other extracellular NTPDases, NTPDase2, -3, and -8, in sepsis is unclear. In the present studies we identified NTPDase8 as a top downregulated gene in the liver of mice submitted to cecal ligation-induced sepsis. Immunohistochemical analysis confirmed the decrease of NTPDase8 expression at the protein level. In vitro mechanistic studies using HepG2 hepatoma cells demonstrated that IL-6 but not TNF, IL-1β, bacteria, or lipopolysaccharide are able to suppress NTPDase8 gene expression. NTPDase8, as well as NTPDase2 and NTPDase3 mRNA was downregulated, whereas NTPDase1 (CD39) mRNA was upregulated in polymorphonuclear leukocytes from both inflamed and septic patients compared to healthy controls. Although the host’s inflammatory response of polymicrobial septic NTPDase8 deficient mice was no different from that of wild-type mice, IL-6 levels in NTPDase8 deficient mice were higher than IL-6 levels in wild-type mice with pneumonia. Altogether, the present data indicate that extracellular NTPDases are differentially regulated during sepsis.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11302-021-09819-1.     

Influence of Canopy Height and Fertilization Levels on the Resistance of Lycopersicon Hirsutum to Aculops Lycopersici (Acari: Eriophyidae)

The objective of this work was to study the effect of NK fertilization levels and canopy height on the resistance of Lycopersicon hirsutum and Lycopersicon esculentum to Aculops lycopersici (Acari: Eriophydae). The effects of NK fertilization levels and canopy height in the leaf size and density of trichomes and their effects on tridecan-2-one (2-TD) and undecan-2-one (2-UD) limiting the attack of A. lycopersici on tomato plants were assessed. Different NK fertilization levels had no effect on the resistance of L. hirsutum to A. lycopersici. No significant differences were found in attack rates of this mite on leaves of the top and median parts of L. hirsutum canopy. The type and density of trichomes were the main determining factor of A. lycopersici attack on tomato plants. High trichome densities and type VI glandular trichomes which produce tridecan-2-one are important resistance factors on tomato plants. L. hirsutum showed a high resistance level to A. lycopersici due to high densities of type VI glandular trichomes and consequently higher levels of tridecan-2-one in its leaves.