BMC Microbiology最新文献

{"title":"16 S rRNA-based molecular identification of coagulase-negative Staphylococcus species in neonates with sepsis and their antibiotic resistance patterns in Ahvaz, Iran.","authors":"Arash Malakian, Sahar Dehghan, Effat Abbasi Montazeri, Mohammad Reza Aramesh, Masoud Dehdashtian, Seyed Mohammad Hassan Aletayeb","doi":"10.1186/s12866-025-03809-8","DOIUrl":"10.1186/s12866-025-03809-8","url":null,"abstract":"<p><strong>Introduction: </strong>Coagulase-negative staphylococci (CoNS) are among the leading causes of neonatal sepsis (NS). NS can be divided into two types: early-onset sepsis (EOS), which usually occurs less than 72 h after birth, and late-onset sepsis (LOS), which can occur 8 to 28 days after birth. According to newly published statistics, the incidence rates of EOS and LOS in neonates are 0.5-3.1% and 2-32%, respectively. This study aimed to determine the prevalence of common CoNS isolates and their antibiotic resistance patterns in NS cases in Ahvaz, Iran.</p><p><strong>Methods: </strong>This cross-sectional study (October 2022-April 2023) was conducted on all neonates (0-28 days old) with NS manifestations admitted to Imam Khomeini Hospital. Blood culture samples were collected and incubated at 37 °C for 24 h. The bacterial isolates were identified via standard biochemical tests, and the Staphylococcus epidermidis strains were identified via polymerase chain reaction (PCR) of the SesC gene. The other suspected CoNS species were identified using 16 S rRNA sequencing.</p><p><strong>Results: </strong>In total, 1221 blood culture bottles were collected from 1330 neonates with NS manifestations. A total of 111 (9.1%) blood cultures were positive for bacterial growth. Overall, 51 staphylococcal isolates, including 39 (76.5%) CoNS species and 12 (23.5%) S. aureus isolates, were identified. Using SesC gene PCR and 16 S rRNA sequencing, the CoNS species were as follows: 28 (71.8%) S. epidermidis, 5 (12.8%) S. hominis, 4 (10.38%) S. haemolyticus and 2 (5.1%) S. warneri. In total, the frequency of NS caused by CoNS isolates was 35.1% (n = 39/111). All CoNS isolates were methicillin resistant and presented the highest antibiotic resistance rates (100.0%) to cefoxitin, ampicillin, erythromycin, and linezolid.</p><p><strong>Conclusions: </strong>This study revealed a high incidence of methicillin-resistant coagulase-negative staphylococci (MRCoNS) with high antibiotic resistance rates in NS patients from Ahvaz. To prevent the spread of these isolates in healthcare systems, measures such as monitoring the optimal use of antibiotics on the basis of the results of laboratory antibiograms seem necessary.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"114"},"PeriodicalIF":4.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11874690/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The implications of mutations in multiple genes associated with ethambutol resistance among multidrug-resistant tuberculosis isolates from China.","authors":"Ma-Chao Li, Wei Wang, Tong-Yang Xiao, Hai-Can Liu, Shi-Qiang Lin, Hao Hang, Xiang-Long Bo, Xiao-Tian Nan, Cheng Qian, Xue-Ting Fan, Xiu-Qin Zhao, Gui-Lian Li, Kang-Lin Wan, Li-Li Zhao","doi":"10.1186/s12866-025-03821-y","DOIUrl":"10.1186/s12866-025-03821-y","url":null,"abstract":"<p><strong>Objectives: </strong>To assess the mutation effects of ethambutol (EMB) resistance-associated genes, including embCAB operon, ubiA, embR, and aftA, on the EMB resistance levels among multidrug-resistant tuberculosis (MDR-TB) isolates from China.</p><p><strong>Methods: </strong>A total of 159 MDR-TB from China had their EMB MICs quantified, and the sequences of the four ethambutol resistance-associated regions were analyzed. A multivariate regression model was established to evaluate the effects of mutations on EMB resistance.</p><p><strong>Results: </strong>Our results showed that overall 95.6% (109/114 isolates) of EMB-resistant isolates harbored at least one mutation within the regions associated with EMB resistance. Most mutations were in embB, particularly in the embB300-500, and the embC-embA intergenic regions. Mutations in other genes were seldom seen and mainly occurred along with mutations in the embB or the embC-embA among the EMB-resistant isolates. DNA sequencing of the embB300-500 and the embC-embA was the most effective approach for detecting EMB resistance, with an accuracy of 91.2%. Nevertheless, some EMB-susceptible isolates still had a single mutation in the gene related to EMB resistance. Moreover, there was a significant correlation between EMB high-level resistance and multiple mutations.</p><p><strong>Conclusion: </strong>Distinct individual mutations, as well as multiple concurrent mutations, within EMB resistance-associated genes, contributed to variable levels of EMB resistance. These results have broadened our understanding of the molecular characteristics of EMB resistance in China.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"107"},"PeriodicalIF":4.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11871839/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular characterization of resistance and biofilm genes of ESKAPE pathogens isolated from clinical samples: examination of the effect of boric acid on biofilm ability by cell culture method.","authors":"Ozgur Celebi, Sumeyye Baser, Mustafa Can Guler, Ali Taghizadehghalehjoughi, Erva Rakici, Elif Aydin, Demet Celebi","doi":"10.1186/s12866-025-03830-x","DOIUrl":"10.1186/s12866-025-03830-x","url":null,"abstract":"<p><p>Biofilm formation ranks first among the resistance and virulence factors crucial in forming ESKAPE pathogens. Once biofilm is formed, treating the infection with existing drugs is often futile. Therefore, in this study, resistant ESKAPE pathogens were isolated from intensive care units and sent to Atatürk University Yakutiye Research Hospital Microbiology Laboratory. This study investigated the biofilm formation and molecular characterization of resistant ESKAPE pathogens isolated from intensive care units. The bacteria's biofilm formation abilities, genes responsible for biofilm formation, and resistance characteristics were identified. The effect of boric acid (BA) on resistance and bacterial genes was evaluated by a bacterial infection cell culture model. The highest biofilm formation was observed in Escherichia coli, Enterococcus spp., and Pseudomonas aeruginosa Enterococcus spp. isolates showed the vanA gene in 14.6% and the vanC gene in 61% of the samples. Among Staphylococcus spp. isolates, 48.3% were MSSA, 34.5% were MRCNS, and 17.2% were MRSA. The KPC gene was detected in 50%, the OXA-48 gene in 40%, and the NDM gene in 15% of the isolates. In P. aeruginosa, the LasI and LasR quorum sensing system genes were found in 38.5% and 30.8% of the isolates, respectively. In E. coli isolates, OXA-48 was present in 35%, KPC in 31.7%, and TEM in 12.5%. BA demonstrated significant activity against ESKAPE pathogens. The combined antimicrobial activity of boron compounds showed a decrease in the expression level of the resistance gene. It will be promising for preventing hospital-associated infections.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"106"},"PeriodicalIF":4.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11871791/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expression of bap gene in multidrug-resistant and biofilm-producing Acinetobacter baumannii clinical isolates.","authors":"Maedeh Kakavan, Mehrdad Gholami, Mohammad Ahanjan, Mohammad Ali Ebrahimzadeh, Maryam Salehian, Fatemeh Roozbahani, Hamid Reza Goli","doi":"10.1186/s12866-025-03806-x","DOIUrl":"10.1186/s12866-025-03806-x","url":null,"abstract":"<p><strong>Introduction: </strong>Acinetobacter baumannii is a significant biofilm-producer and antibiotic-resistant pathogen associated with various infections caused in humans. This study aimed to investigate the expression level of the bap gene in multidrug-resistant and biofilm-producer clinical isolates of A. baumannii.</p><p><strong>Materials and methods: </strong>One Hundred A. baumannii clinical isolates were collected from hospitalized patients and identified by phenotypic and genotypic tests. The antibiotic resistance pattern of the isolates was determined by the disk agar diffusion method. The ability of biofilm production was investigated using the microtiter plate test. This study employed the Real-time PCR method to evaluate the expression level of the bap gene.</p><p><strong>Results: </strong>Ninety nine percent A. baumannii isolates were MDR. However, the highest resistance rate was observed against ciprofloxacin (100%), while ceftazidime was the most effective drug. Also, 49%, 49%, and 2% of the isolates were strong, moderate, and weak biofilm-producing, respectively. However, we detected no strain without the ability to produce biofilm. Most strong and moderate biofilm-former isolates were non-susceptible to all tested antibiotics. An increased expression level of the bap gene was detected in 99% of the isolates. The results of the present study suggest a correlation between the bap gene expression level and the development of multidrug resistance and biofilm formation in A. baumannii isolates.</p><p><strong>Conclusion: </strong>This research emphasizes the importance of biofilm formation in the emergence of multidrug-resistant A. baumannii strains in healthcare settings, making them progressively difficult to control. The bap gene may be a considerable target for the development of novel anti-A. baumannii treatment option and eradication of the biofilm formation by this organism.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"108"},"PeriodicalIF":4.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11871766/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of probiotic Lactobacillus plantarum CM49 on microbial profile and lactobacilli counts in milk of mastitic cattle.","authors":"Muhammad Zeeshan Izhar, Muhammad Nawaz, Tahir Yaqub, Muhammad Avais","doi":"10.1186/s12866-025-03832-9","DOIUrl":"10.1186/s12866-025-03832-9","url":null,"abstract":"<p><strong>Background: </strong>Bovine mastitis is a common udder disease in cattle, mainly caused by bacteria and other infectious agents. Traditionally antibiotics are used for their treatment, but the development of antibiotic resistance has increased the importance of using non antibiotic alternative such as probiotic. In current study a previously in vitro characterized isolate Lactobacillus plantarum CM49 infused into two groups of cattle suffering from clinical mastitis (n = 5) and sub-clinical mastitis (n = 5).</p><p><strong>Results: </strong>The bacterial composition and diversity analysis of milk samples before and after probiotic administration was analyzed using 16S rRNA gene base metagenomic analysis and lactobacillus counts were also evaluated using Real time PCR. The results show that there was an increase in abundance of Proteobacteria and decrease in Firmicutes at phylum level in both groups while major mastitogens genera Staphylococcus and Streptococcus abundance was reduced after treatment in sub-clinical mastitis group (SCMG) and clinical mastitis group (CMG) respectively. Lactobacilli counts evaluated through Real time PCR showed an increase in number, furthermore diversity indices showed an increase in diversity after treatment with probiotic.</p><p><strong>Conclusion: </strong>It is concluded from the results that Lactobacillus plantarum CM49 may serve as promising candidate for improving dysbiosis resulting from mastitis and improving microbial diversity.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"109"},"PeriodicalIF":4.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11871703/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic evidence on the distribution and ecological function of Pseudomonas in hadal zone.","authors":"Yongxin Lv, Lizhi Zhang, Xiangyu Wang, Yu Zhang","doi":"10.1186/s12866-025-03834-7","DOIUrl":"10.1186/s12866-025-03834-7","url":null,"abstract":"<p><p>The hadal zone is the deepest region on Earth. It serves as a depositional zone for the sinking matter from surface ocean and continental margin, aided by its unique V-shaped structure. Due to extreme depth (over 6000 m), normally only organic matter with low degradability typically reaches the bottom of the trench. Concurrently, reports have indicated highly active carbon turnover and dense bacterial cells in the Mariana Trench. There remains a cognitive gap in understanding the connection between this phenomenon and the microbial taxa along with their metabolic activities. Here, we surveyed the Pseudomonas, one of the most widely distributed bacterial genera on Earth. The result revealed widespread distribution of Pseudomonas in the hadal zones. We obtained 21 metagenome-assembled genomes (MAGs) from seawater and sediment samples of the Mariana Trench, including three novel species. Comparative genomic analysis showed that hadal Pseudomonas possess more unique ortholog groups of genes related to energy generation and substances transport, distinct from those in other marine zones. These bacteria exhibit the ability to utilize diverse electron acceptors and accumulate compatible solutes, indicating two key strategies for adaptation for high hydrostatic pressure conditions. Furthermore, predicted genomic capabilities suggest that Pseudomonas could decompose various components of organic matter, particularly aromatics, as supported by metatranscriptomic datasets. These findings significantly enhance our understanding of Pseudomonas diversity and metabolic potential, providing valuable insights into the carbon and nitrogen cycles in hadal trench ecosystems.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"100"},"PeriodicalIF":4.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11869652/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143531145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two virulent Vibrio campbellii phages with potential for phage therapy in aquaculture.","authors":"Huiyu Ding, Keming Shi, Min Hsiao, Wenqing Li, Xin Liu, Jie Xu, Yunlan Yang, Rui Zhang","doi":"10.1186/s12866-025-03803-0","DOIUrl":"10.1186/s12866-025-03803-0","url":null,"abstract":"<p><strong>Background: </strong>As aquaculture continues to expand globally, diseases caused by Vibrio species are becoming increasingly prevalent. Vibriosis encompasses a range of infections, which can lead to symptoms such as skin lesions, hemorrhaging, and high mortality rates in fish and shellfish, especially in high-density farming systems, resulting in significant economic losses. Simultaneously, the extensive use of antibiotics has fostered the emergence of antibiotic-resistant bacteria, exacerbated disease outbreaks, and complicated control measures. Phage therapy, which leverages bacteriophages as natural antibacterial agents, offers a promising eco-friendly alternative to the antibiotics used in aquaculture. This study aimed to evaluate the potential of two vibriophages for phage therapy in aquaculture.</p><p><strong>Results: </strong>Two virulent vibriophages, vB_VcaP_R24D and vB_VcaP_R25D, were isolated from aquaculture wastewater from seafood markets using Vibrio campbellii LMG 11216^T as the host strain. The two vibriophages were identified based on their morphology, infection dynamics, host range, genomic features, lytic activity, and environmental stability. Both phages belong to the podovirus morphotype and exhibit a lytic life cycle characterised by a short latent period (< 10 min). Genomic analyses confirmed the absence of lysogenic genes, virulence factors, and antibiotic-resistance genes, thereby ensuring genetic safety. Additionally, both phages demonstrated high stability over a broad range of temperatures (4-45 °C) and pH (3-10). Lytic curve analyses further indicated a robust lytic efficiency during the logarithmic growth phase of the vibriophages.</p><p><strong>Conclusions: </strong>These biological and genomic characteristics highlight the potential of vB_VcaP_R24D and vB_VcaP_R25D as effective biocontrol agents for mitigating vibriosis in aquaculture. Although this study demonstrates their narrow host range, the possibility of phage infection in other untested hosts cannot be entirely excluded. Furthermore, the findings offer valuable insights for future research on phage-host interactions and the development of phage cocktails to improve disease management in aquaculture systems.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"99"},"PeriodicalIF":4.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11869677/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143531157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genome mining and metabolite profiling illuminate the taxonomy status and the cytotoxic activity of a mangrove-derived Microbacterium alkaliflavum sp. nov.","authors":"Wen-Jin Hu, Li-Xian Deng, Yi-Ying Huang, Xiao-Chun Wang, Jin-Ling Qing, Hao-Jun Zhu, Xing Zhou, Xiao-Ying Zhou, Jie-Mei Chu, Xinli Pan","doi":"10.1186/s12866-025-03801-2","DOIUrl":"10.1186/s12866-025-03801-2","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The genus Microbacterium in the phylum Actinomycetota contains over 100 species to date that little is known about their bioactive metabolites production. In this study, a mangrove sediment-derived strain B2969&lt;sup&gt;T&lt;/sup&gt; was identified as a novel type strain within the genus Microbacterium due to the low 16S rRNA gene sequence similarity (&lt; 99%), and low overall genome relatedness indices (ANI, 75.4%-79.5%; dDDH, 18.5%-22.7%, AAI, 68.7%-76.3%; POCP, 48.3%-65.0%) with the validly named species of the genus. The type strain B2969&lt;sup&gt;T&lt;/sup&gt; (= MCCC 1K099113&lt;sup&gt;T&lt;/sup&gt; = JCM 36707&lt;sup&gt; T&lt;/sup&gt;) is proposed to represent Microbacterium alkaliflavum sp. nov.. The crude extracts of strain B2969&lt;sup&gt;T&lt;/sup&gt; showed weak cytotoxicity against NPC cell lines TW03 and 5-8F, with IC&lt;sub&gt;50&lt;/sub&gt; values of ranging from 3.5 µg/µL to 2.4 µg/µL respectively. Genome analysis of strain B2969&lt;sup&gt;T&lt;/sup&gt; found 8 clusters of genes responsible for secondary metabolite biosynthesis, including cytotoxic compounds desferrioxamines. In addition, the application of liquid chromatography tandem mass spectrometry (LC-MS/MS)-based molecular networking strategy led to the identification of 10 compounds with potent cytotoxic activity in ethyl acetate extracts of strain B2969&lt;sup&gt;T&lt;/sup&gt;. Results from the cytotoxicity assay, genome mining, and metabolite profiling based on LC-MS/MS analysis revealed its ability to produce bioactive compounds.BackgroundMangrove ecosystems are largely unexplored sources of Actinomycetota, which represent potential important reservoirs of bioactive compounds. The genus Microbacterium in the phylum Actinomycetota contains over 100 species to date that little is known about their bioactive metabolites production. In this study, a novel species, namely B2969&lt;sup&gt;T&lt;/sup&gt;, within the genus Microbacterium that showed cytotoxicity against nasopharyngeal carcinoma (NPC) cell lines was isolated from mangrove sediments. Genome mining and metabolic profiling analyses were explored here to assess its biosynthetic potential of metabolites with cytotoxic properties.ResultsHere, a mangrove sediment-derived strain B2969&lt;sup&gt;T&lt;/sup&gt; was identified as a novel species within the genus Microbacterium due to the low 16S rRNA gene sequence similarity (&lt; 99.0%), and low overall genome relatedness indices (ANI, 75.4%-79.5%; dDDH, 18.5%-22.7%, AAI, 68.7%-76.3%; POCP, 48.3%-65.0%) with the type strains of this genus. We proposed that strain B2969&lt;sup&gt;T&lt;/sup&gt; represents a new species, in which the name Microbacterium alkaliflavum sp. nov. is proposed. The strain showed weak cytotoxicity against NPC cell lines TW03 and 5-8F, with IC&lt;sub&gt;50&lt;/sub&gt; values of ranging from 3.512 µg/µL to 2.428 µg/µL respectively. Genome analysis of strain B2969&lt;sup&gt;T&lt;/sup&gt; found 8 clusters of genes responsible for secondary metabolite biosynthesis, including desferrioxamines. In addition, the application of liquid chromatography tandem mass spectrometry (LC-MS/MS)-based molecular networki","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"103"},"PeriodicalIF":4.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11869465/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143531144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tea seedlings growth promotion by widely distributed and stress-tolerant PGPR from the acidic soils of the Kangra valley.","authors":"Rishu Thakur, Praveen Rahi, Ashu Gulati, Arvind Gulati","doi":"10.1186/s12866-025-03811-0","DOIUrl":"10.1186/s12866-025-03811-0","url":null,"abstract":"<p><p>This is the first report of widespread and stress-tolerant PGPR from the tea rhizosphere of the Kangra valley. A total of 493 rhizobacteria were isolated from the major tea-growing regions of the Kangra valley. Molecular fingerprinting of 160 distinct morphotypes using ARDRA and ERIC techniques revealed intergenic and intragenic variability, resulting in the identification of 52 rRNA and 56 ERIC types belonging to 21 distantly related genera, identified by 16S rRNA gene sequencing. Bacillus constituted more than half of the genotypes, followed by Pseudomonas, Burkholderia, Lysinibacillus, Citrobacter, Enterobacter, and Paenibacillus. Bacillus altitudinis, B. cereus, B. megaterium, B. subtilis subsp. inaquosorum, B. methylotropicus, Pseudomonas frederiksbergensis, P. mohnii, and P. moreiii were found to be the most common in the tea rhizosphere across various locations. Quantitative assaying of 42 selected strains revealed significant variations in PGP activities ranging from 55-624 µg/ml for tri-calcium phosphate (TCP) solubilization, 4-3145 nM α-ketobutyrate h/mg/protein ACC-deaminase activity, 2-85 µg/ml IAA-like auxins production, and 2-83% siderophore production. Nine out of 42 PGPR also solubilized aluminium phosphate (Al-P) and iron phosphate (Fe-P). These efficient PGPR are suitable for application in tea soils, which are generally low in available phosphorus, a growth-limiting factor for tea cultivation. Five highly efficient PGPR also showed robust growth under different abiotic stresses under controlled conditions. Inoculum application of 5 efficient and abiotic stress tolerant PGPR showed a significant increment of 1.8-9.4%, 12-16.2%,18.1-30.3% and 21.4-39.2% in plant height, leaf number, fresh and dry weight of tea seedlings under the nursery conditions with 50% reduced NPK concentrations after one year of inoculations, respectively. These selected PGPR genotypes with multifarious PGP activities and natural ability to occur widely can be useful in developing plant microbial inoculants for improving tea productivity.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"102"},"PeriodicalIF":4.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11869635/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143531156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Boosting hypochlorite's disinfection power through pH modulation.","authors":"Timir Baran Sil, Dmitry Malyshev, Marina Aspholm, Magnus Andersson","doi":"10.1186/s12866-025-03831-w","DOIUrl":"10.1186/s12866-025-03831-w","url":null,"abstract":"<p><strong>Purpose: </strong>Hypochlorite-based formulations are widely used for surface disinfection. However, the efficacy of hypochlorite against spore-forming bacteria varies significantly in the literature. Although neutral or low pH hypochlorite solutions are effective sporicides due to the formation of hypochlorous acid (HOCl), their optimal conditions and the specific role of pH in disinfection remain unclear. These conditions also increase the solution's corrosiveness and compromise its shelf life. Therefore, further research is needed to identify the pH conditions that balance solution stability and effective hypochlorite-based spore disinfection.</p><p><strong>Results: </strong>This study investigates the impact of neutral to alkaline pH on the sporicidal efficiency of hypochlorite against a pathogenic Bacillus cereus strain. We apply a 5,000 ppm hypochlorite formulation for 10-min across a pH range of 7.0-12.0, simulating common surface decontamination practices. Our results demonstrate that hypochlorite is largely ineffective at pH levels above 11.0, showing less than 1-log reduction in spore viability. However, there is a significant increase in sporicidal efficiency between pH 11.0 and 9.5, with a 4-log reduction in viability. This pH level corresponds to 2 - 55 ppm of the HOCl ionic form of hypochlorite. Further reduction in pH slightly improves the disinfection efficacy. However, the shelf life of hypochlorite solution decreases exponentially below pH 8.5. To explore the pH-dependent efficacy of hypochlorite, Raman spectroscopy and fluorescence imaging were used to investigate the biochemical mechanisms of spore decontamination. Results showed that lower pH enhances spore permeability and promotes calcium dipicolinic acid (CaDPA) release from the core.</p><p><strong>Conclusion: </strong>Our results highlight the complex relationship between pH, sporicidal efficacy of hypochlorite, and its shelf life. While lower pH enhances the sporicidal efficiency, it compromises the solution's shelf life. A pH of 9.5 offers a balance, significantly improving shelf life compared to previously suggested pH ranges 7.0-8.0 while maintaining effective spore inactivation. Our findings challenge the common practice of diluting sodium hypochlorite with water to a 5,000 ppm solution, as this highly alkaline solution (pH of 11.9), is insufficient for eliminating B. cereus spores, even after a 10-min exposure. These findings are critical for improving disinfection practices, highlighting the importance of optimizing sodium hypochlorite effectiveness through pH adjustments before application.</p>","PeriodicalId":9233,"journal":{"name":"BMC Microbiology","volume":"25 1","pages":"101"},"PeriodicalIF":4.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11869716/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143531143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}