Pseudomonas Strains Research Articles

Molecular analysis of rhizobacteria with insecticidal activity against potato pest Tecia solanivora

ABSTRACT Rhizosphere bacteria, selected by plants for their diverse beneficial functions, have the potential to act as biocontrol agents due to their capability to infect and kill insect pests. One such pest, Tecia solanivora, poses a significant threat to potato crops in Central and South America. However, the capacity of rhizobacteria from potato crops to control T. solanivora remains unclear. This study aimed to evaluate the insecticidal capabilities of rhizobacteria against T. solanivora. Through phenotypic assays and genomic analysis, the virulence factors employed by the rhizobacteria in the infection process were characterised. Two rhizobacteria strains, Enterobacter asburiae, and Raoultella terrigena, exhibited significant insecticidal activity, causing 85% and 77% larval mortality, respectively. Genomic analysis revealed numerous virulence factors in both strains, including enzymes, antimicrobial compounds, volatile organic compounds, and toxins, which contribute to rhizosphere colonisation and the infection and killing of insect pests. Notably, the Tc toxin in E. asburiae and the SdiA receptor in R. terrigena were identified as the most significant virulence factors in these rhizobacteria. Comparative genomics showed that the virulence factors identified in this study are common among known insecticidal rhizobacteria, such as Yersinia entomophaga MH96 and various strains of Pseudomonas. These findings elucidate the infection mechanisms employed by R. terrigena and E. asburiae against T. solanivora, highlighting their potential as biocontrol agents for this pest.

Acanthamoeba castellanii Can Facilitate Plasmid Transfer Between Environmental Pseudomonas spp.

The conditions in which antimicrobial resistance (AMR) genes are transferred in natural environments are poorly understood. Acanthamoeba castellanii (a cosmopolitan environmental amoeba) feeds on bacteria by phagocytosis, which places the consumed bacteria closely together in a food vacuole (phagosome) of the amoeba. This way, amoebae can facilitate genetic exchanges between intra-amoebal bacteria. We studied this phenomenon in the clinically relevant bacteria Pseudomonas oleovorans and Pseudomonas aeruginosa (strain 957). The internalization of both the plasmid donor and recipient bacteria was shown by confocal microscopy. In seven independent experiments, an on average 12-fold increase in transfer of the blaVIM-2 gene between these two Pseudomonas strains was observed in the presence of A. castellanii compared to its absence. Negligible or no plasmid transfer was observed from P. oleovorans to 18 other investigated strains of P. aeruginosa. AMR gene transfer via plasmids between Pseudomonas species is highly strain-dependent and A. castellanii can substantially enhance plasmid transfer. This process of plasmid transfer might also occur between other bacteria and predatory protozoa, such as amoebae that reside in the gut of humans and animals.

The repressor PrtR1 and the global H-NS-like regulators MvaT and MvaV enable the fine-tuning of R-tailocin expression in Pseudomonas protegens

BackgroundBacteria rely on an arsenal of weapons to challenge their opponents in highly competitive environments. To specifically counter closely related bacteria, specialized weapons with a narrow activity spectrum are deployed, particularly contractile phage tail-like particles or R-tailocins. Their production leads to the lysis of the producing cells, indicating that their expression must be carefully orchestrated so that only a small percentage of cells produce R-tailocins for the benefit of the entire population.ResultsIn this study, we set out to better understand how the production of these phage tail-like weapons is regulated in environmental pseudomonads using the competitive plant root colonizer and environmental model strain Pseudomonas protegens CHA0. Using an RNA sequencing (RNA-seq) approach, we found that genes involved in DNA repair, particularly the SOS response program, are upregulated following exposure of the pseudomonad to the DNA-damaging agents mitomycin C and hydrogen peroxide, while genes involved in cell division and primary metabolism are downregulated. The R-tailocin and prophage gene clusters were also upregulated in response to these DNA damaging agents. By combining reverse genetics, transcriptional reporters and chromatin immunoprecipitation sequencing (ChIP-seq), we show that the R-tailocin locus-specific LexA-like regulator PrtR1 represses R-tailocin gene expression by binding directly to the promoter region of the cluster, while the histone-like nucleoid structuring (H-NS) proteins MvaT and MvaV act as master regulators that indirectly regulate R-tailocin cluster expression.ConclusionOur results suggest that at least these three regulators operate in concert to ensure tight control of R-tailocin expression and cell lytic release in environmental Pseudomonas protegens strains.

Effects of Combined Chemical and Biofertiliser Application on Sweet Potato Growth and Yield

Due to its wide application in human food production and industrial uses sweet potato has a high economic value. The proper fertilization of the sweet potato is quite important and includes both inorganic and organic fertilisers. Sweet potato (Ipomoea batatas L.) is gaining popularity as a functional food with increasing global demand because of its health benefits, thus there is a need to enhance on its production and quality. The effectiveness of applying biofertilisers in conjunction with chemical fertilisers and the effect of various beneficial bacterial strains on the Lembayung sweet potato variety was established in this study. A factorial experiment was established using five treatments which included two bacterial strains (Bacillus subtilis and Pseudomonas fluorescens), a commercial biofertiliser and chemical fertiliser. The experiment was conducted in RCBD with four replications. The results of the experiment revealed that the use of biofertilisers in combination with chemical fertilisers significantly increased the tuber yield, growth of the plants and resistance to disease as compared to the other treatments. The treatment that produced the highest tuber yield and growth was the treatment with the use of biofertiliser. The use of biofertilisers greatly reduced the incidence and severity of viral diseases thus revealing their role in disease suppression. This approach not only improves the quality of production, but also promotes sustainable farming, which is in line with the efforts of enhancing soil fertility and increasing production.

Molecular and functional analysis of a putative pyocin S9, with endonuclease activity from P. chlororaphis subsp aurantiaca PB-St2.

Pyocins are bacteriocins which are explicitly associated with pseudomonads. In this study, the genome mining and in-depth sequence analysis identified three similar S9-like (a, b, and c), an S3-like (d) and one R-type pyocin systems from P. chlororaphis subsp aurantiaca PB-St2. The phenotypic screening of bacteriocin production by PB-St2 indicated narrow-spectrum bactericidal activity against closely related Pseudomonas species i.e., Pseudomonas aeruginosa PAi, PAc1, PAc3, PAc4; Pseudomonas fluorescens Psi-RS1 and Pseudomonas kilonensis OSRS3. Herein, the proposed pyocin S9c was further selected for molecular and functional characterization. The presumptive N-terminal receptor binding domain of candidate system lacks significant similarity with any characterized HNH-type pyocin S DNases from P. aeruginosa. In contrast, the cytotoxic domain showed 53% sequence similarity with pyocin S8 and 70% to pyocin S9. Thus, pyocin S9c was suggested as an isoform under the Class I DNase (H-N-H) family in pyocin S9 cluster, commonly found in P. chlororaphis subsp. aurantiaca and P. chlororaphis subsp aureofaciens strains. Molecular screening of the pyocin S9c system revealed its presence in 6 out of 7 tested strains of P. chlororaphis subsp. aurantiaca GS1, GS3, GS4, GS6, ARS38, FS2 and one P. chlororaphis RP4 relative strains, isolated from diverse plant hosts. The 1.59kb fragment consisting of two structural genes of pyocin-immunity operon (S9c) in P. aurantiaca PB-St2 were cloned in pET28a(+) and expressed in Escherichia coli BL21 DE3 (pLysS) strain as a fusion protein with histidine tag. The recombinant cytotoxic protein of pyocin S9c operon was purified with N-term His-tag with a molecular weight of ≈ 50kDa. The identity of target protein was affirmed by tandem mass spectrometry analysis. The purified cytotoxic protein was active against P. chlororaphis subsp. aurantiaca GS7, with a minimum inhibitory concentration of 12.5µg/ml. The mechanism of cytotoxicity was affirmed as a metal-dependent endonuclease by evidence of non-specific hydrolysis of pTZ57R plasmid isoforms. These results indicate that pyocin S9c can contribute to the rhizo-competence of this strain in plant-associated natural habitats, occupied by related Pseudomonas strains.

Harnessing microbial allies: enhancing black alder resilience to PAH stress through microbial symbiosis

Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants that pose significant risks to plant health and ecosystem function. Phytoremediation, using plants in combination with microorganisms, offers a promising strategy for mitigating PAH toxicity. This study investigates the role of PAH-degrading microorganisms in mitigating the phytotoxic effects of PAHs on black alder (Alnus glutinosa L.) seedlings. Specifically, we examined the effects of three microbial strains—Pseudomonas putida Trevisan, Sphingobium yanoikuyae Yabuuchi et al., and Rhodotorula sphaerocarpa (S.Y. Newell & Fell) Q.M. Wang, F.Y. Bai, M. Groenewald & Boekhout—on plant growth and biochemical responses under exposure to naphthalene, pyrene, phenanthrene, and fluorene. The results revealed genotype-dependent variations in plant responses. In family 13-99-1K, S. yanoikuyae significantly enhanced defense mechanisms under phenanthrene exposure, evidenced by reduced malondialdehyde (MDA) levels and increased antioxidant enzyme activity. In contrast, family 41-65-7K exhibited stable shoot height and increased chlorophyll a/b ratio, but a decrease in soluble sugars under P. putida treatment with pyrene. This suggests a shift in metabolic priorities towards growth rather than stress mitigation. These findings highlight the complex interactions between plant genotype, microbial strain, and PAH type, underscoring the potential of microbial-assisted phytoremediation. Our study suggests that tailored microbial inoculants, in combination with appropriate plant genotypes, could optimize phytoremediation efforts in PAH-contaminated environments. Future research should focus on soil-based systems and longer-term evaluations to better understand the dynamics of plant-microbe-PAH interactions.

The Potential Therapeutic Advantages of Bacteriophage Targeting MDR Pseudomonas aeruginosa using the Infection Model of Gallaria mellonella

Aim: The growing problem of antibiotic-resistant bacteria in clinical environ-ments has driven increased interest in bacteriophage therapy, where viruses specifically target and destroy harmful bacteria. This research explores the therapeutic potential of bac-teriophages isolated to combat Multi-drug-resistant Pseudomonas aeruginosa, using Gal-leria mellonella larvae as an experimental model. In vitro susceptibility to multiple antibi-otics was assessed using the double agar overlay technique. Additionally, the survival rate of the larvae was analyzed to determine the phages' capacity to combat bacterial infection in G. mellonella. Background: Resistance to commonly used antibiotics has been steadily increasing over the past few decades, and it has been observed to vary depending on the alternative method employed, such as Bacteriophage Therapy. Objective: Bacteriophage therapy was employed to treat moth wax larvae that were infected with Multidrug-Resistant Pseudomonas aeruginosa. Materials and Methods: The study focused on the Pseudomonas aeruginosa strain PP31, a Multidrug-Resistant Gram Negative bacterium that was obtained from biomedical waste at ICF Hospital in Tamil Nadu, India. Galleria mellonella larvae infected with this multidrug-resistant strain of Pseudomonas were employed for treatment using bacteriophage. Results: It was found that a single phage might infect a particular strain of bacteria in the host. It was demonstrated that MDR Pseudomonas aeruginosa infected larvae must be treated with a single specific phage dose (20μL, 104 PFU/mL) at 6 – hour intervals in order to achieve a 95% survival rate for In vivo research. By counting the number of germs in the larvae, the results were confirmed. Conclusion: Our research shows that although phages were shown to be highly contagious in vitro, specific phage dosages were required for effective treatment in living animals.

Fungi shape genome evolution of bacteria even in the absence of major growth phenotypes

Abstract Studies of microbial interactions often emphasize interactions with large, easily measurable growth differences and short-term ecological outcomes spanning just a few generations. However, more subtle interactions, such as those without obvious phenotypes, may play a significant role in shaping both the short-term ecological dynamics and the long-term evolutionary trajectories of microbial species. We used the cheese rind model microbiome to examine how two fungal species, Penicillium camemberti and Geotrichum candidum, impact global gene expression and genome evolution of the bacterium Pseudomonas carnis LP. Even though fungi had limited impacts on the growth of P. carnis LP, approximately 4–40% of its genome was differentially expressed, depending on the specific fungal partner. When we evolved this Pseudomonas strain alone or in co-culture with each of the fungi, we observed frequent mutations in global regulators of nitrogen regulation, secondary metabolite production, and motility, depending on the fungus. Strikingly, many strains with mutations in the nitrogen regulatory gene ntrB emerged when evolved alone or with G. candidum, but not with P. camemberti. Metabolomic and fitness experiments demonstrate that release of free amino acids by P. camemberti removes the fitness advantages conferred by ntrB mutations. Collectively, these results demonstrate that even in the absence of major short-term growth effects, fungi can have substantial impacts on the transcriptome and genomic evolution of bacterial species.

Antibiotic resistance profile of nitrogen-metabolizing microbes in anoxic‒oxic processes for swine wastewater treatment

The anoxic-oxic (A/O) process is the most common biological method for removing nitrogen (N) from wastewater, but the antibiotic resistance profile of N-metabolizing microbes in A/O processes remains largely underexplored. Here we demonstrated a significant positive correlation between various types of N-metabolizing genes and antibiotic resistance genes (ARGs) in swine wastewater A/O processes across China. We assembled 180 high-quality genomes of dominant N-metabolizing microbes (12.6% of the total metagenome-assembled genomes), all harboring transcriptionally active ARGs. And Pseudomonas was identified as the primary N-metabolizing genus and major ARG host. Among 1110 culturable N-metabolizing isolates, 22.34% were Pseudomonas strains showing high N removal capacity and multi-antibiotic resistance. Moreover, plasmid-mediated ARG transfer further heightened resistance risks. Overall, these findings highlight a significant ARG risk among predominant N-metabolizing microbes in A/O treatment processes, underscoring the urgency of balancing N removal performance with resistance control in wastewater treatment processes.

Integrated analysis of transcriptomics and metabolomics and high-throughput amplicon sequencing reveals the synergistic effects of secondary metabolites and rhizosphere microbiota on root rot resistance in Psammosilene tunicoides.

Psammosilene tunicoides is a plant with significant medicinal and ecological value, exhibiting remarkable medicinal properties, particularly in anti-inflammatory, antioxidant, and immune-regulatory effects. Root rot is one of the primary diseases affecting Psammosilene tunicoides, leading to a significant decline in its quality. In this study, we utilized an integrated analysis of transcriptomics, metabolomics, high-throughput amplicon sequencing, and culturomics for revealing the difference of healthy samples (CH) and diseased samples (CD) and studying the defense mechanism of P. tunicoides in resisting root rot. Transcriptome revealed distinct patterns of gene expression between healthy root samples (HR) and diseased root samples (DR) of P. tunicoides. The Key enzyme genes involved in triterpene (e.g., HMGS, DXS, SQS, CYP450) and flavonoid (e.g., PAL, CHS, CHI) biosynthesis pathways were significantly upregulated in DR. Consistent results were observed in the metabolomic analysis, where triterpene saponins and flavonoids were more highly accumulated in DR than in HR. Microbiome data indicated a significant enrichment of Actinobacteria at the genus level in the rhizosphere soil of diseased samples (DS) compared to healthy samples (HS) while the mostly beneficial growth-promoting bacterial groups were found in DR root endophytes, including Enterobacter, Pseudomonas, Klebsiella, Stenotrophomonas, and Bacillus. Through culturomics, we successfully isolated and identified over 220 bacterial strains from the rhizosphere soil of diseased samples, including genera including Bacillus, Streptomyces, Cupriavidus, Pseudomonas, and Paenarthrobacter. Notably, the strain Pseudomonas sp., which was significantly enriched in DR, exhibited a clear antagonistic effect against Fusarium oxysporum. Co-occurrence network analysis of multi-omics data revealed that many Actinomycetes positively correlated with triterpenoid and flavonoid compounds and their key genes. Therefore, we conclude that these secondary metabolites may could resist pathogen invasion directly or serve as an "intermediate medium" to recruit growth-promoting microorganisms to resistant the root rot. This study investigates the "Plant-Microbe" interaction network associated with root rot resistance in P. tunicoides, revealing its significant implications for the ecological cultivation and management of this species.

Total glucosinolate content of arugula (Eruca sativa Mill.) supplemented with rhizobacteria-enriched bio-slurry

Arugula is a member of Brassicaceae that has a high antioxidant content of glucosinolate. Bio-slurry is a kind of liquid fertilizer derived from sap of cow dung. Bio-slurry in combination with rhizobacterial can maximize decomposition and make nutrients more available. The research aimed to determine the total glucosinolate content in arugula due to the application of bio-slurry enriched with rhizobacteria. The study used a randomized complete block design with a single factor consisting of 9 levels, i.e., the combination of 3 types of rhizobacteria (Pseudomonas, Bacillus, Pseudomonas + Bacillus) and 3 doses of bio-slurry (0, 100, and 200 mL). The results showed that the application of Pseudomonas & Bacillus + 200 mL bio-slurry produced a higher antioxidant content than other inputs. The combination of bio-slurry fertilizer with rhizobacterial provides a higher ability than control to increase plant growth rates and the biosynthesis of glucosinolate. The optimal substitution for maximizing nutrient uptake in arugula growth was achieved with a bio-slurry dose of 200 mL, where the combined application of Pseudomonas and Bacillus strains enhanced plant growth and glucosinolate content. Keywords: antioxidant capacity; Bacillus; bacterial; biofertilizer; Pseudomonas

Harnessing microbial communities for enhanced plant resilience against diseases.

Phytophthora infestans (P. infestans) and other plant infections threaten global agriculture and food security. This research incorporated Pseudomonas strains in microbial consortia to boost plant tolerance to P. infestans. The P. infestans fungus causes collapse and deterioration in many crops like potatoes by quickly spreading through their tubers and leaves in warm, damp weather. The main goals were to identify effective Pseudomonas strains (those with high inhibitory activity), test their interactions (both inhibitory and synergistic), and determine the effect of inoculum density on disease treatment. We used the following methodologies, from potato shoots and rhizosphere samples, Nine different strains of the antifungal bacterium Pseudomonas which were identified with preliminary antifungal activity. Bintje showed the greatest resistance to P. infestans among the three potato types that were examined. Methods utilized comprised: Quantification of bacterial density and growth, the inhibitory assays for P. infestans, experiments on leaf disc infections, Assessing the severity of an infection, Analysis of zoospore discharge. Studies on the integrated development of bacteria and valuation using statistical methods. The study revealed the complexity of microbial interactions, host-specific reactions, and cell density's impact on treatment success. The study suggests using Pseudomonas strains as biocontrol agents, advancing sustainable agriculture. Microbial consortia disease management requires advanced methodologies, according to the findings. Investigating long-term ecological impacts on soil health, microbial diversity, and crop yield sustainability; validating identified microbial consortia through field trials; evaluating scalability and economic viability; and researching genetic engineering for customized disease control are recommended. Results suggest a shift from chemical pesticides to environmentally friendly plant disease control considering its ethical and regulatory implications. This study emphasizes the intricacy of microbial interactions and the need for informed biocontrol decisions. Their study also increases ecological knowledge and encourages innovative, sustainable worldwide agriculture.

Particulate matter pollution alters the bacterial community structure on the human skin with enriching the Acinetobacter and Pseudomonas.

Particulate matter pollution alters the bacterial community structure on the human skin with enriching the Acinetobacter and Pseudomonas.

Metabolic design of a platform Pseudomonas strain producing various phenazine derivatives.

Metabolic design of a platform Pseudomonas strain producing various phenazine derivatives.

Description of Pseudomonas gorinensis sp. nov., a plant growth-promoting bacterium that modulates stomatal aperture.

A polyphasic taxonomic approach was used to characterize a previously isolated plant growth-promoting Pseudomonas strain designated as NT2T and a Pseudomonas strain designated as TKP (JCM 19688), both of which were found to manipulate plant stomatal immunity. Both strains shared 100% 16S rRNA gene sequence identity. Phylogenetic trees based on single and concatenated sequences of the housekeeping genes gyrB, rpoB, rpoD and 16S rRNA, as well as whole-genome sequences, clustered NT2T and TKP together, clearly separated from the closest Pseudomonas spp., which belonged to the Pseudomonas fluorescens complex. NT2T showed average nucleotide identities (ANIs) of 87.8% (ANIb) and 89.9% (ANIm) and a 37.4% digital DNA-DNA hybridization score with Pseudomonas grimontii DSM 17515T, the species with the highest genome sequence similarity. On the contrary, the comparison between NT2T and TKP showed very high ANI (ANIb=99.67, ANIm=99.93) and digital DNA-DNA hybridization scores (98.90%). NT2T and TKP differed from closely related species in relation to arginine dihydrolase activity, aesculin and gelatin hydrolysis, N-acetyl-d-glucosamine, maltose, adipate, phenylacetate, p-hydroxy-phenylacetic acid, Tween 40, glycyl-l-proline, d-maltose, d-galactonic acid lactone, α-hydroxy butyric acid, myo-inositol, sucrose, l-histidine, d-malic acid, l-rhamnose and acetic acid assimilation, NaCl-tolerance range and pyocyanin production (fluorescence on King A medium). The major fatty acids in NT2T and TKP were C16 : 0, C16 : 1 ω7t and C18 : 1 ω7c. The results of this polyphasic study allowed the genotypic and phenotypic differentiation of NT2T and TKP from the closest Pseudomonas and confirmed that these strains represent a novel species, for which the name Pseudomonas gorinensis sp. nov. is proposed with NT2T (DSM 114757T=LMG 32751T) as the type strain.

Native Bacteria Are Effective Biocontrol Agents at a Wide Range of Temperatures of Neofusicoccum parvum, Associated with Botryosphaeria Dieback on Grapevine.

Botryosphaeria dieback, a significant grapevine trunk disease (GTD) caused by various pathogens, represents a serious threat to viticulture. Biocontrol emerges as a promising sustainable alternative to chemical control, aligning toward environmentally friendly viticultural practices. This study evaluated the in vitro, in vivo, and in situ biocontrol potential of Chilean native bacteria isolated from wild flora and endophytic communities of grapevine against Neofusicoccum parvum. In vitro biocontrol assays screened 15 bacterial strains at 10, 22, and 30 °C, identifying four Pseudomonas strains with >30% mycelial growth inhibition. In diffusible agar and double plate assays, plant growth-promoting bacteria AMCR2b and GcR15a, which were isolated from native flora, achieved significant inhibition of N. parvum growth, with reductions of up to ~50% (diffusible agar) and up to ~46% (double plate). In vivo experiments on grapevine cuttings revealed that strains AMCR2b and GcR15a inhibited mycelial growth (17-90%); younger grapevines (1-5 years) were more susceptible to N. parvum. In situ trials using Vitis vinifera L. cv. Cabernet Sauvignon and Sauvignon Blanc demonstrated higher fungal susceptibility in Sauvignon Blanc. These results highlight the potential of Pseudomonas sp. AMCR2b and GcR15a to be effective biocontrol agents against GTDs at a wide range of temperatures, contributing to sustainable viticulture.

Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of Pseudomonas spp. Isolated from Milk and Dairy Products.

Dairy-borne Pseudomonas spp., known for causing spoilage, may also exhibit antibiotic resistance and form biofilms, enhancing their persistence in dairy environments and contaminating final products. This study examined biofilm formation and antibiotic resistance in 106 Pseudomonas spp. strains isolated from milk, whey, and spoiled dairy products. Phylogenetic analysis (based on partial ileS sequences) grouped most strains within the P. fluorescens group, clustering into the P. fluorescens, P. gessardii, P. koorensis, and P. fragi subgroups. Biofilm formation in polystyrene microplates was assessed at 6 °C and 25 °C by crystal violet staining. After 48 h, 72% and 65% of Pseudomonas strains formed biofilms at 6 °C and 25 °C, respectively, with higher biomass production at 6 °C. High biofilm producers included most P. fluorescens, P. shahriarae, P. salmasensis, P. atacamensis, P. gessardii, P. koreensis, and P. lundensis strains. The adnA gene, associated with biofilm formation, was detected in 60% of the biofilm producers, but was absent in P. fragi, P. lundensis, P. weihenstephanensis, and P. putida. Antibiotic susceptibility was tested using the disk diffusion method. All strains were susceptible to amikacin and tobramycin; however, 73% of the strains were resistant to aztreonam, 28% to imipenem and doripenem, 19% to ceftazidime, 13% to meropenem, and 7% to cefepime. A multiple antibiotic resistance index (MARI) > 0.2 was found in 30% of the strains, including multidrug-resistant (n = 15) and extensively drug-resistant (n = 3) strains. These findings highlight Pseudomonas spp. as persistent contaminants and antibiotic resistance reservoirs in dairy environments and products, posing public health risks and economic implications for the dairy industry.

Investigation of the Potentials of Local Strains of Pseudomonas for Aquaculture Water Treatment

The need for human and animal food production cannot be over-emphasized. Aquaculture and related activities have become an important sustainable business in Nigeria. Water pollution rates have increased in modern times owing to the various chemical usage. The receiving water bodies therefore constitute a potential source of danger to both humans and animals. Several metabolites of the bacteria can cause detoxification of polluted water. There is a need to develop indigenous bacteria consortia for application in the treatment of wastewater bodies in order to reduce importation and earn local earnings. Some indigenous Pseudomonas strains were isolated from waste soil sites using standard microbiological techniques including pour-plating serially diluted 1g of the soil sample in 9 ml of sterile peptone water. The basic features of the developed discrete colonies were studied, sub-cultured and then the purified isolates; PM05, PM78, PM13 and PM56 were challenged by growing them respectively with wastewater. Specifically, the NH4+-N content decreased from 230 mg/L to a range of between 0.5 to 12 mg/L. While NO3-N decreased from 25 mg/l to between 5.3 to 14.6mg/L. NO2-N decreased from 12mg/L to between 1.3 to 5.7 mg/L. and available/total N decreased from 235 to 103 mg/L respectively. The results indicated that the strains generally have the potential to remove nitrogen through the metabolic pathway of nitrogen assimilation which may make them fit for further development for bio-remediation purposes. Also, the results generated will add to the previous knowledge that such important strains can be obtained from the local soils and sediments in Nigeria.

Utilization of Crab Shell Waste for Value-Added Bioplastics by Pseudomonas-Based Microbial Cell Factories.

With the development of the aquatic products processing industry, 6-8 million tons of shrimp and crab shell waste are produced globally annually, but, due to the lack of high-value conversion technology, crab shells are often discarded in large quantities as a by-product of processing. Pseudomonas-based microbial cell factories are capable of biosynthesis of high-value products using a wide range of substrates; however, there is currently no reliable fermentation model for producing high-value chemicals using crab shell waste by Pseudomonas strains. In this study, we first explored the culture conditions of shell fermentation using KT2440 through single-factor and orthogonal experiments, and the optimized fermentation parameters obtained are given as follows: a temperature of 30 °C, fermentation time of 42 h, substrate solid-liquid ratio of 7%, and rotational speed of 200 rpm. After optimization, the maximum cell growth was increased by 64.39% from 350.67 × 108 CFU/mL to 576.44 × 108 CFU/mL. Combined with engineering modification, two engineered strains, KT+IV and KT+lasBT, expressing exogenous proteases, were obtained, and the maximum growth was increased from 316.44 × 108 CFU/mL to 1268.44 × 108 CFU/mL and 616.89 × 108 CFU/mL, which were 300.84% and 94.94% higher, respectively. In addition, the engineered strain KT+NtrcT-D55E, which regulates nitrogen metabolism, was obtained, and the accumulation of intracellular polyhydroxy fatty acid esters (PHA) was increased from 20.00 mg/L to 78.58 mg/L, which was a significant increase of 292.93% relative to the control group. This study provides a theoretical basis and technical support for the high-value utilization of shrimp and crab shell resources and the development of environmentally friendly bioproducts.

Carbapenem Resistant Pseudomonas Aeruginosa: A Multicenter Study on Prevalence, Distribution, and Risk Factors across Six Health Facilities in Yaoundé, Cameroon

Carbapenem-resistant Pseudomonas aeruginosa is a significant public health threat, especially in low and middle-income countries. These strains are known to cause outbreaks, and their isolation continues to increase, further limiting therapeutic options. In Cameroon, however, there is limited data on the resistance profiles of circulating Carbapenem-resistant Pseudomonas aeruginosa strains. This study aimed to determine the prevalence, distribution and susceptibility profile of Carbapenem-resistant Pseudomonas aeruginosa isolates from six health facilities in Yaoundé, Cameroon. An analytical cross-sectional study was conducted over nine months (November 2023–July 2024). Carbapenem-resistant Pseudomonas aeruginosa isolates from clinical specimens were collected and re-identified. After culturing on cetrimide and nutrient agar, biochemical identification was done using the API 2ONE system. Antimicrobial susceptibility testing was performed to assess resistance to carbapenems and other antibiotics. Carbapenemase and extended-spectrum Beta-lactamases production in Carbapenem resistant Pseudomonas aeruginosa was detected using the Carbapenem inhibition and combined disc methods. Of the 217 isolates, 125 (representing 57.6%) were confirmed as Pseudomonas aeruginosa, with 31.2% (39/125) resistant to carbapenems. Among these, 48.7% (19/39) were resistant to imipenem, and 51.3% (20/39) were resistant to meropenem. Carbapenemase production was observed in 46.2% (18/39), while coproduction of carbapenemase and extended-spectrum Beta-lactamases was observed in 28.20% (11/39). High resistance was also seen to cephalosporins (54.4%) and penicillin (59.2%). A majority of Carbapenem-resistant Pseudomonas aeruginosa isolates had a multiple antibiotic resistance index ≥ 0.2. This study underscores the growing public health concern posed by Carbapenem-resistant Pseudomonas strains. Enhanced surveillance is crucial to curb the dissemination and spread of these strains.