Sp Strain Research Articles

Synthesis of Nodupetide Analogue: Substitution of β- to α-hydroxy Acid

Nodupetide, a cyclodepsipeptide with the potential as an antimicrobial agent, was isolated from the fermentation of the fungi Nodulisporium sp strain IFB-A163. It possessed antibacterial activity against Pseudomonas aeruginosa and revealed an insecticidal activity. In our effort to synthesized nodupeptide, the preparation of the (3S,4S)-3-hydroxy-4-methylhexanoic acid (HMHA) as one of the nodupetide residue was found to be challenging, where it is not commercially available and the synthetic trial of the HMHA was not successful. This led us to synthesize nodupetide derivative by replacing HMHA with its a-hydroxy acid to give the analogue [(2S,3S)-Hmp]2-nodupetide. A combination of solid- and solution-phase peptide synthesis was applied in the synthesis nodupetide analogue. Esterification on the resin for synthesis [(2S,3S)-Hmp]2-nodupetide was achieved by placing the reaction at the last stage of the linear peptide synthesis and obtained in overall yield of 4.3 %. We also conducted antimicrobial activity screening for [(2S,3S)-Hmp]2-nodupetide and its linear precursor, showing inactive activity. The alter of hydrophobicity on the nodupetide analogue has very important role in the difference of bioactivity compared to their parent compound. HIGHLIGHTS The synthesized analogue compound has not been reported previously we studied the synthesis strategy of cyclodepsipeptide. We studied the change of beta hydroxy carboxylic acid residue to alpha hydroxy carboxylic acid, which has a very significant effect on biological activity. GRAPHICAL ABSTRACT

An integrated approach for plastic polymer degradation by the gut bacterial resident of superworm, Zophobas morio (Coleoptera:Tenebrionidae).

The potential of superworm to remove certain plastic polymers has recently been noted. In this study, aerobic bacterial strains were isolated from the gut of Zophobas morio larvae which were fed with polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) polymers. Strains P2 (Leminorella), P6 (Bacillus), P9 (Bacillus), and P5 (Citrobacter) were associated with the highest PS (2.7%), PP (1.3%), PET (1.1%), and PE (0.42%) weight loss after 28days, respectively. Pretreatments including thermal treatment (80°C for 10days), weathering (4months in the free environment), and nitric and sulfuric acids (1 N, 10days) improved the degradation of PE (1.3%), PET (1.9%), PP (5.2%), and PS (8.3%) by the same strains, respectively. Further analyses on the PS degradation by Leminorella sp. P2 revealed acid pretreatment promoted the formation of the C = C, C = O, and O-H functional groups. Surface irregularities, as well as a 3.6-fold increase in surface roughness, were observed in the PS film subjected to biodegradation. The contact angle dropped from 98.4° to 42.2° following the biodegradation. Bacterial depolymerization was confirmed by the 8.7% and 3.4% reduction of Mn and Mw and the change in polydispersity from 1.65 to 1.75. The results suggest that Zophobas morio microbiota in combination with abiotic pretreatment can be considered for plastic waste management.

Removing multiple refractory organic pollutants in wastewater by cell bioaugmentation and genetic bioaugmentation with Rhodococcus sp. strain p52

Bioaugmentation is an appealing remediation strategy to treat refractory organic pollutants in contaminated environments. In this study, activated sludge was bioaugmented with Rhodococcus sp. strain p52 to treat synthetic wastewater containing multiple refractory organic pollutants (dibenzofuran, dibenzo-p-dioxin, and phenanthrene). Bioaugmentation of activated sludge reactors with strain p52 alleviated the adverse effects of refractory pollutants on the chemical oxygen demand and ammonia nitrogen removal capacity of the reactors and enhanced the removal of the refractory organic pollutants, especially highly refractory compound dibenzo-p-dioxin. Toxicity of the refractory pollutants to activated sludge bacteria was attenuated due to contaminant degradation by strain p52. Genetic bioaugmentation mediated by catabolic plasmid transfer from strain p52 to activated sludge bacteria and cell bioaugmentation occurred along with successful colonization and proliferation of strain p52. In addition, a potential metabolically mutualistic relationship existed between strain p52 and activated sludge bacteria for refractory pollutants degradation. Both refractory organic pollutants input and strain p52 bioaugmentation profoundly influenced the structure of the activated sludge bacterial community and drove bacterial community shifts in different directions. This study provides insights into the activities of bioaugmented bacteria and bioaugmentation technology for environmental contaminant remediation.

Different Roles of Dioxin-Catabolic Plasmids in Growth, Biofilm Formation, and Metabolism of Rhodococcus sp. Strain p52.

Microorganisms harbor catabolic plasmids to tackle refractory organic pollutants, which is crucial for bioremediation and ecosystem health. Understanding the impacts of plasmids on hosts provides insights into the behavior and adaptation of degrading bacteria in the environment. Here, we examined alterations in the physiological properties and gene expression profiles of Rhodococcus sp. strain p52 after losing two conjugative dioxin-catabolic megaplasmids (pDF01 and pDF02). The growth of strain p52 accelerated after pDF01 loss, while it decelerated after pDF02 loss. During dibenzofuran degradation, the expression levels of dibenzofuran catabolic genes on pDF01 were higher compared to those on pDF02; accordingly, pDF01 loss markedly slowed dibenzofuran degradation. It was suggested that pDF01 is more beneficial to strain p52 under dibenzofuran exposure. Moreover, plasmid loss decreased biofilm formation, especially after pDF02 loss. Transcriptome profiling revealed different pathways enriched in upregulated and downregulated genes after pDF01 and pDF02 loss, indicating different adaptation mechanisms. Based on the transcriptional activity variation, pDF01 played roles in transcription and anabolic processes, while pDF02 profoundly influenced energy production and cellular defense. This study enhances our knowledge of the impacts of degradative plasmids on native hosts and the adaptation mechanisms of hosts, contributing to the application of plasmid-mediated bioremediation in contaminated environments.

In vivo fitness of sul gene-dependent sulfonamide-resistant Escherichia coli in the mammalian gut.

The widespread sulfonamide resistance genes sul1, sul2, and sul3 in food and gut bacteria have attracted considerable attention. In this study, we assessed the in vivo fitness of sul gene-dependent sulfonamide-resistant Escherichia coli, using a murine model. High fitness costs were incurred for sul1 and sul3 gene-dependent E. coli strains in vivo. A fitness advantage was found in three of the eight mice after intragastric administration of sul2 gene-dependent E. coli strains. We isolated three compensatory mutant strains (CMSs) independently from three mice that outcompeted the parent strain P2 in vivo. Whole-genome sequencing revealed seven identical single nucleotide polymorphism (SNP) mutations in the three CMSs compared with strain P2, an additional SNP mutation in strain S2-2, and two additional SNP mutations in strain S2-3. Furthermore, tandem mass tag-based quantitative proteomic analysis revealed abundant differentially expressed proteins (DEPs) in the CMSs compared with P2. Of these, seven key fitness-related DEPs distributed in two-component systems, galactose and tryptophan metabolism pathways, were verified using parallel reaction monitoring analysis. The DEPs in the CMSs influenced bacterial motility, environmental stress tolerance, colonization ability, carbohydrate utilization, cell morphology maintenance, and chemotaxis to restore fitness costs and adapt to the mammalian gut environment.IMPORTANCESulfonamides are traditional synthetic antimicrobial agents used in clinical and veterinary medical settings. Their long-term excessive overuse has resulted in widespread microbial resistance, limiting their application for medical interventions. Resistance to sulfonamides is primarily conferred by the alternative genes sul1, sul2, and sul3 encoding dihydropteroate synthase in bacteria. Studying the potential fitness cost of these sul genes is crucial for understanding the evolution and transmission of sulfonamide-resistant bacteria. In vitro studies have been conducted on the fitness cost of sul genes in bacteria. In this study, we provide critical insights into bacterial adaptation and transmission using an in vivo approach.

KSA-1, a naturally occurring Ambler class A extended spectrum β-lactamase from the enterobacterial species Kosakonia sacchari

BackgroundSeveral bacterial species belonging to the Gammaproteobacteria possess intrinsic class A β-lactamase genes that may represent a source of further dissemination and acquisition to other Gram-negative species. Here we characterised KSA-1 class A β-lactamase, the gene of which was identified within the chromosome of an environmental Enterobacterales species, namely Kosakonia sacchari, which was also recently identified as the progenitor of an MCR-like colistin-resistance determinant. MethodsIn silico analysis using the GenBank database identified a class A β-lactamase gene within the chromosome of K. sacchari SP1 (GenBank accession no. WP_017456759). The corresponding protein KSA-1 shared 63% amino acid identity with the intrinsic CKO-1 from Citrobacter koseri and 53% with TEM-1. Using the K. sacchari DSM 100203 reference strain as a template, blaKSA-1 was amplified, cloned into the plasmid pUCp24 and expressed in Escherchia coli TOP10. Minimal inhibitory concentrations and kinetic parameters were obtained from the purified enzyme. ResultsK. sacchari strain SP1 conferred resistance to amino-, carboxy- and ureido-penicillins only. Once produced within E. coli, KSA-1 showed a typical clavulanic acid-inhibited extended spectrum β-lactamase associated with a peculiar temocillin resistance profile. Kinetic assays were performed using a purified extract of KSA-1 and demonstrated a high hydrolysis rate for benzylpenicillin and piperacillin, as well as weakly extended spectrum cephalosporins. Determination of inhibitory constants showed 50% inhibitory concentration values of 2.2, 3 and 1.8 nM for clavulanic acid, tazobactam and avibactam, respectively. Analysis of sequences surrounding the blaKSA-1 gene did not reveal any mobile element that could have been involved in the acquisition of this β-lactamase gene in that species. ConclusionKSA-1 is a class A extended spectrum β-lactamase distantly related to known extended spectrum or broad-spectrum Ambler class A β-lactamases, which is highly resistant to temocillin. The blaKSA-1 gene could be considered as intrinsic within the species.

Influence of physicochemical characteristics on the growth and guaiacol production of Alicyclobacillus acidoterrestris in fruit juices

Alicyclobacillus acidoterrestris is a bacterium known for causing spoilage in the taste and odour of fruit juices due to its thermoacidophilic nature. Its spoilage is attributed to the formation of guaiacol, which requires the presence of suitable precursors in the juices that A. acidoterrestris can metabolize. Therefore, A. acidoterrestris could exhibit different behaviour depending on the physicochemical characteristics the juice. In this study, we aimed to evaluate the behaviour of five A. acidoterrestris strains in seven different fruit juices by monitoring total cell and spore populations and quantifying guaiacol production. Also, physicochemical and phenolic profile, focusing on antimicrobials and guaiacol precursors, were analysed to better understand differences. Results showed growth in orange, apple, and plum juices for all the tested strains, with total cell populations reaching approximately 7 log cfu/mL, except for plum juice. In persimmon juice, growth was only observed in 3 out of 5 strains, for both total cells and spores. In contrast, all strains were inhibited in peach, black grape, and strawberry juices, maintaining a consistent population around 4 log cfu/mL. A strong negative correlation was observed between bacterial population and compounds such as kaempferol (for strains R3, R111, and P1), cyanidin chloride (for strains R111 and P1), and p-coumaric acid (for strain 7094 T). Regarding guaiacol production, orange and persimmon juices exhibited the highest guaiacol levels, with strain P1 (362.3 ± 12.6 ng/mL) and strain EC1 (325.1 ± 1.4 ng/mL) as the top producers, respectively. Plum, black grape, and strawberry juices showed similar guaiacol concentrations (16.9 ± 2.8 to 105.0 ± 33.7 ng/mL). Vanillin was showed positive correlations with guaiacol production in almost all strains (7094 T, R3, R111, and P1), with correlation coefficients of 0.97, 0.99, 0.82, and 0.87, respectively. We have reported different behaviour of A. acidoterrestris strains depending on juice type. Despite growth inhibition observed in some juices, enough guaiacol quantities to spoil the juice can be produced. This highlights the necessity of exploring strategies to prevent guaiacol production, even under growth restriction.

Genetic Diversity of the Common Black Carp Strain (Cyprinus carpio var. baisenensis)

The Common Black Carp Strain (Cyprinus carpio var. baisenensis), known for its black skin, is commonly cultured in the integrated rice-agriculture (IRA) system in Guangxi province, China. This study aimed to compare the genetic diversity of three common carp strains/populations (Common Black Carp Strain, Huanghe, and Songpu) using resequencing data. The genome-based method reveals a significant difference (p < 0.05) in identified loci and SNP frequency (p < 1 × 10−6) between the Songpu (Sp) or mirror carp and Huanghe (Hh) new strain. Additionally, the Common Black Carp Strain (Bk) exhibits a higher number of Tajima’s D values, possibly due to its population size and mutations within its entire genome. The average value of population nucleotide diversity (π) for the Bk is 1.706 × 10−4 while the mean number for the Hh and Sp strains is 1.691 × 10−4 Heterozygosity analysis results indicate that the Bk has the highest F coefficient compared to the Sp and Hh hybrids. This suggests that the isolated population of the Bk may have experienced a decrease in population size as a result of environmental disturbances in the IRA system. PCA results further reveal that all individuals of the Bk, except for one, are clustered together, while individuals of the Hh form a separate group. On the other hand, Sp displays a distinct distribution pattern. The comparative study of the genetic diversity of the Bk provides baseline data on its genome makeup. Assessing genetic diversity and genetic structure is critical for fisheries management and the conservation of critically endangered fish species.

Magnetotactic Bacteria from Skudai River in Johor, Malaysia: Isolation and Characterization

Isolation of Magnetotactic Bacteria (MTB) has gained significant interest in multidisciplinary fields. In this study, MTB sample was harvested from the Skudai River in Johor Bahru, Malaysia. Subsequently, the isolated pure MTB cell was cultured with enrichment growth media in agar plates, and identified by Biochemical tests and 16S rRNA. Based on the results, the sequence gene of the MTB is related to Alcaligenes sp strain SUM 123, which is a Gram-negative bacterium in the Betaproteobacteria class. The size and shape of isolated bacterium and the magnetosomes produced were observed under Transmission Electron Microscope (TEM). The Field Scanning Electron Microscope-X-ray Energy Diffraction (FESEM-EDX) analysis was used to determine the metals accumulation of intracellular magnetosomes in Alcaligenes sp. strain SUM 123.

Expression patterns of Mal genes and association with differential maltose and maltotriose transport rate of two Saccharomyces pastorianus yeasts.

Beer brewing is a well-known process that still faces great challenges, such as the total consumption of sugars present in the fermentation media. Lager-style beer, a major worldwide beer type, is elaborated by Saccharomyces pastorianus (Sp) yeast, which must ferment high maltotriose content worts, but its consumption represents a notable problem, especially among Sp strains belonging to group I. Factors, such as fermentation conditions, presence of maltotriose transporters, transporter copy number variation, and genetic regulation variations contribute to this issue. We assess the factors affecting fermentation in two Sp yeast strains: SpIB1, with limited maltotriose uptake, and SpIB2, known for efficient maltotriose transport. Here, SpIB2 transported significantly more maltose (28%) and maltotriose (32%) compared with SpIB1. Furthermore, SpIB2 expressed all MAL transporters (ScMALx1, SeMALx1, ScAGT1, SeAGT1, MTT1, and MPHx) on the first day of fermentation, whereas SpIB1 only exhibited ScMalx1, ScAGT1, and MPH2/3 genes. Some SpIB2 transporters had polymorphic transmembrane domains (TMD) resembling MTT1, accompanied by higher expression of these transporters and its positive regulator genes, such as MAL63. These findings suggest that, in addition to the factors mentioned above, positive regulators of Mal transporters contribute significantly to phenotypic diversity in maltose and maltotriose consumption among the studied lager yeast strains.IMPORTANCEBeer, the third most popular beverage globally with a 90% market share in the alcoholic beverage industry, relies on Saccharomyces pastorianus (Sp) strains for lager beer production. These strains exhibit phenotypic diversity in maltotriose consumption, a crucial process for the acceptable organoleptic profile in lager beer. This diversity ranges from Sp group II strains with a notable maltotriose-consuming ability to Sp group I strains with limited capacity. Our study highlights that differential gene expression of maltose and maltotriose transporters and its upstream trans-elements, such as MAL gene-positive regulators, adds complexity to this variation. This insight can contribute to a more comprehensive analysis needed to the development of controlled and efficient biotechnological processes in the beer brewing industry.

Evaluation of the Effectiveness of Streptomyces sp. Against Biofilm-Forming Bacteria and Starch-Protein degradation

Streptomyces sp. play important role in controlling pathogenic bacteria by using different mechanisms so this study aims to diagnose the Streptomyces sp. and select strains having the ability to inhibit biofilm-forming bacteria and degradation proteins and starch. The capacity of bacteria to produce biofilms was examined by staining with 1% crystal violet. The ability to inhibit biofilm-forming bacteria, proteolytic and amylolytic, were determined by bacterial drop and well diffusion methods. The bacteria capable of creating biofilms were isolated from urinary tract infection and identified by biochemical reactions and sequencing the 16S rRNA gene. The Selected 6 Streptomyces strains which were isolated from soil are capable of inhibiting the growth of Escherichia coli and capable of degrading protein and starch. The strain STV1 was selected for 16S rRNA gene sequencing with standard isolates. Isolation of Escherichia coli capable of forming biofilm from urinary tract infection. Selection of Streptomyces sp strains capable of inhibiting biofilm-forming bacteria. The research is the first step to studying the application of Streptomyces sp in inhibiting biofilm-forming bacteria and in treating organic matter.

Microbiological Surveillance of Salmonella Strains in the Effluents of the Teaching Hospital (CHU) of Yopougon and Cocody, Côte d'Ivoire

Diarrhoeal diseases are a major public health problem worldwide, with salmonellosis being a leading cause of foodborne illness in humans. Environmental pollution from healthcare activities, particularly from the discharge of hospital effluent into urban sewer systems, poses a significant threat. These effluents can carry microorganisms, antibiotic residues and detergents that contribute to the development and spread of bacterial multiresistance. In Abidjan, the capital of Côte d'Ivoire, hospital wastewater is not treated before being discharged into the sewer system. This untreated wastewater eventually flows into the Ebrié lagoon, a critical water source for many local communities. The dependence of the lagoon's population on these waters raises significant public health concerns, particularly with regard to potential contamination with pathogenic bacteria such as Salmonella. The aim of this study was to assess the presence of Salmonella in hospital wastewater to understand the risk of contamination and to inform potential mitigation strategies. A total of 60 wastewater samples were collected: 30 from the teaching hospital (CHU) of Yopougon and 30 from Cocody. Upon analysis, no Salmonella sp strains were detected in any of the samples. However, 28 bacterial strains exhibiting characteristics similar to Salmonella were isolated, suggesting the presence of potentially virulent pathogens. In Yopougon's samples, 14 strains of Proteus mirabilis and 2 strains of Klebsiella sp were identified. In Cocody 's samples, 12 strains of Citrobacter freundii sp were isolated. These findings highlight the importance of monitoring and treating hospital wastewater to prevent the spread of potentially harmful bacteria into the environment.

Effects of nitrogen deposition on the rhizosphere nitrogen-fixing bacterial community structure and assembly mechanisms in Camellia oleifera plantations.

Increased nitrogen deposition is a key feature of global climate change, however, its effects on the structure and assembling mechanisms of the nitrogen-fixing bacteria present at the root surface remain to be elucidated. In this pursuit, we used NH4NO3 to simulate nitrogen deposition in a 10-year-old Camellia oleifera plantation, and set up four deposition treatments, including control N0 (0 kg N hm-2 a-1), low nitrogen N20 (20 kg N hm-2 a-1), medium nitrogen N40 (40 kg N hm-2 a-1) and high nitrogen N160 (160 kg N hm-2 a-1). The results showed that nitrogen deposition affected the soil nitrogen content and the structure of the nitrogen-fixing bacterial community. Low nitrogen deposition was conducive for nitrogen fixation in mature C. oleifera plantation. With increasing nitrogen deposition, the dominant soil nitrogen-fixing bacterial community shifted from Desulfobulbaceae to Bradyrhizobium. When nitrogen deposition was below 160 kg N hm-2 a-1, the soil organic matter content, total nitrogen content, nitrate nitrogen content, ammonium nitrogen content, urease activity, soil pH and nitrate reductase activity influenced the composition of the nitrogen-fixing bacterial community, but the stochastic process remained the dominant factor. The results indicate that the strains of Bradyrhizobium japonicum and Bradyrhizobium sp. ORS 285 can be used as indicator species for excessive nitrogen deposition.

Metabolic Engineering of Saccharomyces cerevisiae for Production of Canthaxanthin, Zeaxanthin, and Astaxanthin.

The sustainable production of natural compounds is increasingly important in today's industrial landscape. This study investigates the metabolic engineering of Saccharomyces cerevisiae for the efficient biosynthesis of valuable carotenoids: canthaxanthin, zeaxanthin, and astaxanthin. Utilizing a tailored parental yeast strain, Sp_Bc, we optimized the carotenoid pathway by screening and identifying CrtW and CrtZ enzymatic variants. The CrtW variant from Bradyrhizobium sp. achieved a canthaxanthin titer of 425.1 ± 69.1 µg/L, while the CrtZ variant from Pantoea ananatis achieved a zeaxanthin titer of 70.5 ± 10.8 µg/L. Additionally, we optimized carotenoid production by exploring enzyme fusion strategies for all three studied carotenoids and organelle compartmentalization specifically for enhancing astaxanthin synthesis. We further improved carotenoid production by integrating the optimal gene constructs into the yeast genome and deleting the GAL80 gene, enabling the use of sucrose as a carbon source. The engineered strain Sp_Bc-Can001 ∆gal80 was evaluated in a 5 L bioreactor fermentation, achieving a notable canthaxanthin titer of 60.36 ± 1.51 mg/L using sucrose. This research conclusively establishes S. cerevisiae as a viable platform for efficient carotenoid biosynthesis and, for the first time in this yeast system, illustrates sucrose's viability as a carbon source for canthaxanthin production. These findings pave the way for sustainable, cost-effective carotenoid production at an industrial scale.

Potential Biocontrol Microorganisms Causing Attenuated Pathogenicity in Plasmopara viticola.

A phenomenon of pathogenicity attenuation of Plasmopara viticola was consistently observed during its subculture on grape. To clarify the causes of attenuated pathogenicity of P. viticola, culturable microbes were isolated from the P. viticola mass (mycelia, sporangiophores, and sporangia) in each generation and tested for their biocontrol efficacies on grape downy mildew (GDM). The results showed that the incidence of GDM decreased with the increase in the number of subculture times on both vineyard-collected leaves and grape leaves from in vitro-grown seedlings. The number of culturable microbial taxa on the surface of P. viticola decreased, whereas the population densities of four specific strains (i.e., K2, K7, P1, and P5) increased significantly with the increase in subculture times. Compared with the control, the biocontrol efficacies of the bacterial strain K2 reached 87.5%, and those of both fungal strains P1 and P5 reached 100.0%. Based on morphological characteristics and molecular sequences, strains K2, P1, and P5 were identified as Curtobacterium herbarum, Thecaphora amaranthi, and Acremonium sclerotigenum, respectively, and these three strains survived very well and multiplied on the surface of P. viticola. As the number of times P. viticola was subcultured increased, all three of these strains became the predominant strains, leading to greater P. viticola inhibition, attenuated P. viticola pathogenicity, and effective GDM biological control. To the best of our knowledge, this is the first report of C. herbarum and T. amaranthi having biological control activity against GDM.

Co-fermentation of peanut milk by selected lactic acid bacteria on its protein structure, Ara h 1's immunoreactivity, physical-chemical properties and sensory attributes

The commercialization of peanut products is presently limited by the absence of a reliable method of degrading the allergen while yielding acceptable flavor. We examined the effect of co-fermentation of peanut milk by Lactobacillus plantarum strain P1 and Lactobacillus pentosus strain Y6 (FPM-LE) on its protein structure, Ara h 1's immunoreactivity, physicochemical properties and flavor. Protein analysis showed that protein folding, and degradation occurred during the fermentation and significantly degraded peanut proteins greater than 20 kDa. The immunoreactivity of FPM-LE of Ara h 1 was most reduced by 74.65% compared to sterilized peanut milk. We found that FPM-LE had higher acidity, water holding capacity, viscosity. The flavor of FPM-LE was significantly improved compared to peanut milk fermented by L. plantarum P1 or L. pentosus Y6 alone. The characteristic flavor metabolites (CFM) of FPM-LE were 1-hexanol. Overall, FPM-LE as a product has strong potential to become a hypoallergenic, peanut milk drink with excellent taste and flavor.

Isolation of Aspergillus sp from some Decomposing Fruits and Vegetables from Banana Rhyzosphere Soil for Citric Acid Production

Aims: The general objective of this study is to isolate certain strains capable of producing citric acid. Place and Duration of Study: Sample collection was carried out on two types of organic matter. Sampling was done from February to April 2021 in 3 municipalities in Abidjan with 10 samples per site. Methodology: To carry out this work, isolation and purification of Aspergillus sp strains were carried out. Macroscopic and microscopic identifications of the mold isolates were carried out. The search for aflatoxin-producing molds was carried out. The analysis ended with a screening of molds capable of synthesizing citric acid. Results: Aspergillus niger, Aspergillus sp1 and Aspergillus sp2 showed no fluorescence, while Aspergillus flavus, Aspergillus candidus and Aspergillus fumigatus showed fluorescent spots, indicating the presence of aflatoxin. Conclusion: Aspergillus isolates capable of producing citric acid were isolated during this study. Aspergillus niger, Aspergillus sp1 and Aspergillus sp2 do not produce aflatoxin and have the capacity to synthesize citric acid.

Biodegradation of DEP, DIBP, and BBP by a psychrotolerant Sphingobium yanoikuyae strain P4: Degradation potentiality and mechanism study.

Phthalic acid esters (PAEs) are human made chemicals widely used as plasticizers to enhance the flexibility of plastic products. Due to the lack of chemical bonding between phthalates and plastics, these materials can easily enter the environment. Deleterious effects caused by this chemo-pollutant have drawn the attention of the scientific community to remediate them from different ecosystem. In this context, many bacterial strains have been reported across different habitats and Sphingobium yanoikuyae strain P4 is among the few psychrotolerant bacterial species reported to biodegrade simple and complex phthalates. In the present study, biodegradation of three structurally different PAEs viz., diethyl phthalate (DEP), di-isobutyl phthalate (DIBP), and butyl benzyl phthalate (BBP) have been investigated by the strain P4. Quantitative analyses through High-performance liquid chromatography (HPLC) revealed that the bacterium completely degraded 1g/L of DEP, DIBP, and BBP supplemented individually in minimal media pH 7.0 within 72, 54, and 120h of incubation, respectively, at 28°C and under shake culture condition (180rpm). In addition, the strain could grow in minimal media supplemented individually with up to 3g/L of DEP and 10.0g/L of DIBP and BBP at 28°C and pH 7.0. The strain also could grow in metabolites resulting from biodegradation of DEP, DIBP, and BBP, viz. n-butanol, isobutanol, butyric acid, ethanol, benzyl alcohol, benzoic acid, phthalic acid, and protocatechuic acid. Furthermore, phthalic acid and protocatechuic acid were also detected as degradation pathway metabolites of DEP and DIBP by HPLC, which gave an initial idea about the biodegradation pathway(s) of these phthalates.

The effect of epetraborole on the transcriptome and proteome profiles of an Escherichia coli strain overexpressing leuS, Leucyl-tRNA Synthetase

Epetraborole (EP) is a boron-containing antibiotic known for its effectiveness against gram-negative enteric bacteria and Mycobacterium species. It is designed to bind and inhibit the LeuS enzyme (Leucyl-tRNA Synthetase), which is encoded by the essential gene leuS in Escherichia coli. EP inhibits protein translation, impeding bacterial growth. However, when leuS is overexpressed in a recombinant plasmid, the amount of EP required for growth inhibition needs to be increased. This study explored the impact of EP on the transcriptome and proteome of E. coli overexpressing leuS, aiming to reveal additional gene and pathway insights beyond LeuS, shedding light on the biochemical players orchestrating the bacterium’s molecular response. 2D-PAGE Proteomics analysis identified four differentially regulated proteins influenced by EP in the leuS overexpression strain. Notably, LeuA and DeoA emerged as identified proteins. EP may affect LeuA in the cells overexpressing LeuS, which could result in truncated LeuA protein variants. Transcriptomics analyses, based on microarray data, revealed 23 up-regulated and 9 down-regulated genes responding to EP in the overexpression strain (p2). Based on the statistical analyses, the first five up-and down-regulated genes showing the highest fold differences in their mRNA levels are yiaW, mglB, narH, ybiO, flgB and yhdY, deoR, recX, yobB, potF, respectively. Analyses using the Omics Dashboard pathway and String indicate that the EP effect on the leuS overexpressing strain mainly induces alterations in the expression of genes related to the cell exterior, regulation, and response to stimuli. It is suggested that EP and higher levels of LeuS may interfere with the translational and transcriptional regulation of the expression of the leuA gene, which encodes the first enzyme, 2-isopropylmalate synthase, in L-leucine biosynthesis. This study offers new insights into the effects of EP on the bacterium, specifically when the level of the aminoacyl-tRNA synthetase LeuS is increased.

Antagonistic effect of Bacillus and Pseudomonas combinations against Fusarium oxysporum and their effect on disease resistance and growth promotion in watermelon.

We aimed to develop an effective bacterial combination that can combat Fusarium oxysporum infection in watermelon using in vitro and pot experiments. In total, 53 strains of Bacillus and 4 strains of Pseudomonas were screened. Pseudomonas strains P3 and P4 and Bacillus strains XY-2-3, XY-13, and GJ-1-15 exhibited good antagonistic effects against F. oxysporum. P3 and P4 were identified as Pseudomonas chlororaphis and Pseudomonas fluorescens, respectively. XY-2-3 and GJ-1-15 were identified as B. velezensis, and XY-13 was identified as Bacillus amyloliquefaciens. The three Bacillus strains were antifungal, promoted the growth of watermelon seedlings and had genes to synthesize antagonistic metabolites such as bacilysin, surfactin, yndj, fengycin, iturin, and bacillomycin D. Combinations of Bacillus and Pseudomonas strains, namely, XY-2-3+P4, GJ-1-15+P4, XY-13+P3, and XY-13+P4, exhibited a good compatibility. These four combinations exhibited antagonistic effects against 11 pathogenic fungi, including various strains of F. oxysporum, Fusarium solani, and Rhizoctonia. Inoculation of these bacterial combinations significantly reduced the incidence of Fusarium wilt in watermelon, promoted plant growth, and improved soil nutrient availability. XY-13+P4 was the most effective combination against Fusarium wilt in watermelon with the inhibition rate of 78.17%. The number of leaves; aboveground fresh and dry weights; chlorophyll, soil total nitrogen, and soil available phosphorus content increased by 26.8%, 72.12%, 60.47%, 16.97%, 20.16%, and 16.50%, respectively, after XY-13+P4 inoculation compared with the uninoculated control. Moreover, total root length, root surface area, and root volume of watermelon seedlings were the highest after XY-13+P3 inoculation, exhibiting increases by 265.83%, 316.79%, and 390.99%, respectively, compared with the uninoculated control. XY-13+P4 was the best bacterial combination for controlling Fusarium wilt in watermelon, promoting the growth of watermelon seedlings, and improving soil nutrient availability.