CURRENT MICROBIOLOGY

Kineococcus halophytocola sp. nov., Isolated from Leaves of Halophyte Sesuvium portulacastrum L
Thanompreechachai J, Butdee W, Chantavorakit T, Suriyachadkun C and Duangmal K
An aerobic, Gram-stain-positive, motile, coccus-shaped actinomycete, designated strain LSe6-4, was isolated from leaves of sea purslane (Sesuvium portulacastrum L.) in Thailand and subjected to a polyphasic taxonomic studies. Growth of the strain occurred at temperatures between 15 and 38 °C, and with NaCl concentrations 0-13%. The 16S rRNA gene sequences analysis indicated that the strain was most closely related to Kineococcus endophyticus KLBMP 1274 (99.2%), and Kineococcus mangrovi L2-1-L1 (99.0%). The genome of strain LSe6-4 was estimated to be 4.22 Mbp in size, with DNA G+C content of 74.57%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) relatedness values between strain LSe6-4 and the closely related species were less than the threshold values for identifying a novel species. Strain LSe6-4 showed morphological and chemotaxonomic characteristics of the genus Kineocoocus. The whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, with arabinose, galactose, and ribose as whole-cell sugars. The predominant menaquinone was MK-9(H). The polar lipid profile composed of phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid, three unidentified aminophospholipids, and an unidentified aminolipid. Major cellular fatty acids (> 10% of total fatty acids) were anteiso-C and iso-C. It is evident from the combination of genotypic and phenotypic characteristics that strain LSe6-4 represents a novel species of the genus Kineococcus, for which the name Kineococcus halophytocola sp. nov. is proposed. The type strain is strain LSe6-4 (= TBRC 17798 = NBRC 116401).
Comparative Analysis of the Probiotic Features of Lysinibacillus and Enterobacter Strains Isolated from Gut Tract of Triploid Cyprinid Fish
Fang ZX, Kuang XY, Li YH, Yu RX, Wang F and Luo SW
Gut mucosal immunity of teleost is mainly governed by mucosa-associated lymphoid tissues (MALT) and indigenous microbiota on mucosal surfaces of gut tract, which can confer protection against pathogenic invasion. However, the probiotic features of bacterial isolates from gut tract of triploid cyprinid fish (TCF) were largely unclear. In this study, Lysinibacillus and Enterobacter strains were isolated for probiotic identification. Whole genome sequencing (WGS) analysis indicated that Lysinibacillus and Enterobacter isolates possessed a variety of functional genes associated with probiotic features. Biofilm-forming activity (BFA) were one of the most important probiotic features, which can enable probiotic strains to communicate with indigenous microbiota by forming sessile community and then confer protection against stressors and invading pathogens. In this study, Lysinibacillus and Enterobacter isolates displayed high levels of BFA, hydrophobicity as well as aggregating potentials. Moreover, supernatants of probiotic isolates not only decreased pathogenic BFA and growth activity, but also showed high decomposing activity to macronutrients. These results indicated that probiotic isolates from gut tract of TCFs may pose protective roles in health of farmed fish.
A Comprehensive Review on Exploring the Potential of Phytochemicals and Biogenic Nanoparticles for the Treatment of Antimicrobial-Resistant Pathogenic Bacteria
Murugan S, Senthilvelan T, Govindasamy M and Thangavel K
Antimicrobial resistance (AMR) is an escalating global health concern that results in approximately 700,000 deaths annually owing to drug-resistant infections. It compromises the effectiveness of conventional antibiotics, as well as fundamental medical procedures, such as surgery and cancer treatment. Phytochemicals, natural plant constituents, and biogenic nanoparticles synthesized through biological processes are pharmacological alternatives for supplementing or replacing traditional antibiotics. These natural compounds exhibit a diverse range of bioactive properties, including antibacterial, anti-inflammatory, and antioxidant activities, and have the potential to overcome bacterial resistance mechanisms. However, their limited solubility, bioavailability, and stability have limited their therapeutic potential. Nanotechnology, particularly the utilization of biogenic nanoparticles, offers the potential to overcome these limitations by enhancing the biosafety, stability, and controlled release of phytochemical compounds, thereby enabling a more effective combination of resistant pathogens. This review examines current research on the combinatorial application of phytochemicals and biogenic nanoparticles, with emphasis on their capacity to address AMR. This study presents a novel perspective on the concurrent utilization of phytochemicals and biogenic nanoparticles, which may enhance antibacterial efficacy while mitigating toxicity. This review provides specific and innovative insights into the novelty, sustainability, and eco-friendly aspects of these approaches to address multidrug-resistant infections, highlighting their role in emerging as a transformative strategy for AMR management through the integration of natural and biogenic resources.
Enhanced Mosquito Larvicidal Efficacy and Dehairing Properties of Bacillus thuringiensis Serovar israelensis Strain VCRC-B649 Isolated from Malabar Coast, India
Kunnikuruvan A, Vijayakumar A, Sivaprakasam M, Padmanaban H, Mandodan S, Gangmei K, Lukose J, Bora B, Gupta B, Ashokkumar M, Balakrishnan V and Subbiah P
In recent years, there has been a global threat from emerging vector-borne diseases (VBD), despite the implementation of several vector control programs. Considering the benefits of bacterial pesticides, the present study aimed to isolate potential mosquitocidal bacteria from the various soil types collected from the Kasaragod (12.5°N, 75.0°E) district of Kerala, India. One bacterial strain was isolated from the coastal alluvium soil and showed promising mosquitocidal activity. The mosquitocidal isolate was identified as Bacillus thuringiensis serovar israelensis strain VCRC-B649 through phylogenetic analysis of whole genome sequence. LC values against Culex quinquefasciatus, Aedes aegypti, and Anopheles stephensi larvae were determined as 0.0064, 0.0072, and 0.0101 mg/L, and LC values were 0.0127, 0.0140, and 0.019 mg/L. Comparative analysis of larvicidal activity of this strain has revealed more efficacy than the WHO reference strain of B. thuringiensis var. israelensis (H14) The cry and cyt gene profile of this isolate is found to be similar to WHO reference strain of B. thuringiensis var. israelensis (H14). This new isolate has not shown any adverse effects against aquatic non-target organisms. Further evaluation of its morphological, biochemical characteristics and growth kinetics revealed similarities with already reported B. thuringiensis strains. Sporulated culture at 72 h showed maximum (20.6 ± 1.5 mm) proteolytic activity and animal skin (goat skin) dehairing property and revealed the industrial applications of this new strain. This is the first report on the isolation of mosquitocidal bacterial strain with enzyme-producing property from the Malabar coastal region and it was proven to be a more suitable alternative biocontrol agent for controlling the disease transmitting mosquito vectors with translational value.
Intrasporangium zincisolvens sp. nov., A Novel Actinobacterium Isolated from Rhizosphere Soil
Feng LY, Zhao JY, Shi ZF, Li MG, Pu T, Shi ZL, Liu X, Wang Y, Li LL and Yang PW
A novel phosphate-solubilizing and zinc-solubilizing actinobacterium strain YIM S08009 was isolated from rhizosphere soil collected from Pinus yunnanensis in Wuliangshan National Nature Reserve, Pu'er City, Yunnan Province, southwest PR China. Cells of strain YIM S08009 were Gram-stain-positive, non-motile, irregular rods to cocci, and formed yellow and white colonies on nutrient agar. Growth was observed at 10-40 °C (optimum 25-35 °C), pH 6.0-8.5 (optimum 7), and 0-4% (w/v) NaCl (optimum 1%). The cell wall peptidoglycan contained LL-diaminopimelic acid. The whole-cell sugars were mannose, ribose, glucose, and galactose. The predominant menaquinone was MK-8(H). Major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, unknown lipid, and 3 unknown phospholipids. The predominant fatty acids were iso-C, iso-C and iso-C. The DNA G + C content was 72.6%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM S08009 belonged to genus Intrasporangium, and was most closely related to Intrasporangium flavum MUSC 78, with 99.0% 16S rRNA gene sequence similarity. Strain YIM S08009 shared 90.1% orthologous average nucleotide identity (OrthoANI) and 39.8% digital DNA-DNA hybridization (dDDH) with I. flavum MUSC 78. The genome of strain YIM S08009 contained phosphate-solubilizing genes (SenX3, RegX3, pstSCAB, ugpBAEC, phoA) and zinc-solubilizing genes (znuABC, zupT), and the strain had also demonstrated in vitro phosphorus and zinc solubilization. Based on the genotypic and phenotypic analyses, strain YIM S08009 (= CGMCC 1.60168 = NBRC 116604 = KCTC 59021) represents a novel Intrasporangium species, for which the name Intrasporangium zincisolvens sp. nov. is proposed.
Isolation and Identification of Apiospora intestini from Hedera nepalensis Leaf Blight and Determination of Antagonism of Phomopsis sp
Liu J, Sun Y, Liu M, Gou C, Li H, Yang F and Lu J
In order to identify the pathogen responsible for Hedera nepalensis leaf blight and investigate effective biocontrol strategies, samples were collected from 10 significantly infected areas at Southwest Forestry University; four to six infected leaves were gathered from each area, followed by the isolation and purification of strains from the infected plant leaves using tissue isolation and hyphae-purification techniques. We conducted an examination of the biological characteristics and compared the inhibitory effects of different concentrations of Phomopsis sp. (50%, 25%, 16.7%, 12.5%, and 10%) with 20 µg/mL of synthetic fungicides (Mancozeb, Carbendazim, Polyoxin, and Hymexazol) on the pathogen, while also assessing the control efficacy of Phomopsis sp. against the pathogen in the greenhouse. The internal transcribed spacer (ITS) region, β-tubulin (TUB), and translation elongation factor 1-alpha (TEF) analysis revealed that the highly virulent strain causing H. nepalensis leaf blight was Apiospora intestini. Additionally, it was found that 25% Phomopsis sp. significantly inhibited Apiospora intestini when compared to synthetic fungicides, and Phomopsis sp. supernatant possesses both protective and curative effects against the plant diseases caused by Apiospora intestini. The results of this study serve as a reference for the prevention and treatment of H. nepalensis leaf blight.
Molecular Characterization of Yellow Mosaic Disease Causing Begomoviruses in Pigeonpea (Cajanus cajan L.) from Three Agro-ecological Zones of India
Akram M, Kumar D, Saurav S, Saxena M, Saxena DR, Kamaal N and Dixit GP
Pigeonpea (Cajanus cajan L.) plants exhibiting symptoms of yellow mosaic disease (YMD) were collected in winter 2023 from multiple agricultural fields of Kanpur, Sehore, and Madhubani, representing three different agro-ecological zones in India. The recorded disease incidence ranged from 3 to 5%, 1 to 4%, and 12 to 20% in these zones, respectively. This study aimed to identify and characterize the causal agent, suspected to be a begomovirus, an emerging plant pathogen of pigeonpea causing YMD. Total DNA was extracted from 28 YMD-affected leaf samples and subjected to rolling circle amplification for PCR-based virus detection. Of all the tested samples, one tested positive for mungbean yellow mosaic virus (MYMV), while the remaining tested positive for mungbean yellow mosaic India virus (MYMIV). Subsequently, PCR-based amplification and sequencing of the full-length DNA-A and DNA-B components were conducted. BLASTn analysis revealed that the assembled sequences of the DNA-A and DNA-B components had the highest nucleotide identity with MYMIV (DNA-A: 97-99%, DNA-B: 95-97%) and MYMV (DNA-A: 99%, DNA-B: 98%). Phylogenetic analysis supported these findings. Additionally, the DNA-A and DNA-B components obtained from each sample were found to be cognate, with over 92% similarity in their common region. Thus, the cognate DNA components constituted the isolates of MYMIV and MYMV identified from pigeonpea. The identified isolates exhibited the typical genome organization of an Old World bipartite begomovirus, with no recombination events detected. This study reports, for the first time, the complete annotated genomes of MYMIV from Sehore and Madhubani, as well as MYMIV and MYMV from Kanpur, infecting pigeonpea.
Role of Novel Chlorella vulgaris SSAU8 in Improving the Soil Health Under Induced Drought Stress
Maurya N, Sharma A, Agrawal M and Sundaram S
The severe climate change has caused a drastic water level disparity around the globe, which eventually has been one of the biggest problems of this era related to land degradation. This has caused the multidimensional impact on ecology, the environment, and their components. Algae, one of the ancient micro-engineers, are involved in the functioning of soil microcosm. Therefore, this study has utilized a novel alga, Chlorella vulgaris SSAU8 to observe the impact of low water potential induced by PEG-6000 (polyethylene glycol). The study has utilized the UV-Vis spectrophotometer to explore the nature of cyanobacteria by examining biomass and pigment concentrations. The assessment also includes the photosystem response, which was recorded by the Dual-modulation kinetic fluorometer FL3500/F (PSI, Brno, Czech Republic, version 3.7.0.1). The effect of PEG-6000-induced drought was seen to inhibit growth and biomass synthesis at > 30 g L concentration. It was also observed that the microbe could easily shuffle its photosystem behavior to nullify the effect of high PEG-6000 concentration, which shows the potential of the microbe in the water-deficient area and can be an important aspect to enhance soil fertility. Non-photochemical quenching and heat dissipation play a crucial role in cyanobacteria tolerating drought conditions. So, overall, this study thoroughly explores the behavior of Chlorella vulgaris SSAU8 in artificial drought stress and paves a way to combat one of the major environmental issues of the current era.
Thymol as a Novel Plant-Derived Antibacterial Agent for Suppressing Xanthomonas citri pv. malvacearum in Cotton
Aslam MN, Khaliq H, Zhao H, Moosa A, Maqsood A, Farooqi MA, Bilal MS, Mahmood T and Mukhtar T
Xanthomonas citri pv. malvacearum (Xcm) associated with bacterial blight disease is a significant and widespread pathogen affecting cotton worldwide. The excessive use of harmful chemicals to control plant pathogens has exerted a negative impact on environmental safety. Thymol is a monoterpene phenol present in the essential oils of plants belonging to Lamiaceae family. In this study the antimicrobial activity of thymol was evaluated against Xcm. The minimum inhibitory concentration (MIC) and 99.9% bactericidal concentration (MBC) of thymol against Xcm were 2 and 4 mg/mL, respectively. The effect of MIC and MBC of thymol against Xcm was assessed on the Luria-Bertani medium. The effect of thymol on intercellular ATP levels, membrane potential, and motility in Xcm was assessed using fluorescence spectrometry for membrane potential and firefly luciferase-based assay for ATP levels. Thymol ruptured the cellular membrane of Xcm, resulting in decreased intracellular ATP concentrations, intracellular leakage of genetic material, and changes in membrane potential. Scanning electron microscopy images supported the impact of thymol on the cell membrane of Xcm. Moreover, thymol inhibited the swimming motility and biofilm formation of Xcm at concentrations equal to or above the MIC and MBC. In contrast, sub-MIC concentrations of thymol had little to no impact on the virulence of Xcm. In conclusion, thymol demonstrated the potential as a strong bactericidal compound against Xcm.
Reclassification of Salisediminibacterium haloalkalitolerans Sultanpuram et al. 2015 as a Later Heterotypic Synonym of Salisediminibacterium halotolerans Jiang et al. 2012
Wang Y, Wang H, Quadri SR, Quach NT, Li WJ, Wang F, Yuan J, Chen C, Narsing Rao MP and Kang YQ
In the present study, the taxonomic position of Salisediminibacterium haloalkalitolerans was evaluated by determining the 16S rRNA gene sequence similarity, genome relatedness, and phylogenetic analyses. The 16S rRNA gene sequences extracted from the genomes of Salisediminibacterium haloalkalitolerans 10nlg and Salisediminibacterium halotolerans DSM 26530 showed 100% similarity, supporting their classification as the same species. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between S. haloalkalitolerans and S. halotolerans were 97.7 and 80.2%, respectively, above the cutoff value (95-96% ANI; 70% dDDH) for species delineation. S. haloalkalitolerans and S. halotolerans should be classified as the same species because the 16S rRNA gene phylogeny and phylogenomic tree (based on 71 bacterial single-copy genes) showed no genetic divergence between them. Based on the above results and the rule of priority in nomenclature, we propose to reclassify Salisediminibacterium haloalkalitolerans Sultanpuram et al. 2015 as a later heterotypic synonym of Salisediminibacterium halotolerans Jiang et al. 2012.
Reclassification of Salinisphaera halophila Zhang et al. 2012 as a Later Heterotypic Synonym of Salinisphaera orenii Park et al. 2012
Quadri SR, Sathish M, Quach NT, Li WJ and Narsing Rao MP
In the present study, the taxonomic position of Salinisphaera halophila (NZ_AYKF00000000) and Salinisphaera orenii (NZ_AYKH00000000) was re-evaluated. In addition, their metabolic potentials and mechanisms for mitigating stress conditions were determined. Comparisons of 16S rRNA gene sequences, analysis of the phylogenetic tree, phylogenomic tree, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) values were conducted. The 16S rRNA gene sequence similarity between Salinisphaera halophila YIM 95161 and Salinisphaera orenii MK-B5 was 100%. In phylogenetic and phylogenomic trees, Salinisphaera halophila YIM 95161 and Salinisphaera orenii MK-B5clustered together. Both species encode genes for glycolysis, citrate cycle, pentose phosphate pathway, Entner-Doudoroff pathway, nitrate assimilation, and assimilatory sulfate reduction. They employ salt-in and salt-out strategies to mitigate salt stress. The ANI and dDDH values between Salinisphaera halophila YIM 95161and Salinisphaera orenii MK-B5were 96.6 and 72.1%, respectively, above the cut-off (95-96% for ANI and 70% for dDDH) for species delineation. Based on the above results, we propose to reclassify Salinisphaera halophila Zhang et al. 2012 as a later heterotypic synonym of Salinisphaera orenii Park et al. 2012.
Characterization, Identification, and Biosafety Evaluation of Multifaceted Traits of Plant Growth-Promoting Endophytes for Ameliorating Productivity of Forage Sorghum
Kaur J, Pandove G, Sidhu AS, Brar SK, Singh ND, Arora V and Walia SS
Endophytes are bacteria that inhabit host plants for most of their life cycle without causing harm. In the study, 15 endophytic bacteria were isolated from 30 forage Sorghum plants and assessed for various plant growth-promoting (PGP) traits, such as phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, ammonia production, siderophore production, gibberellic acid production, Indole-3-acetic acid (IAA) production, and zinc solubilization. One isolate, JJG_Zn, demonstrated multiple PGP activities and was identified as Enterobacter sp. through 16S rRNA sequencing. Considering the concept of 'One health,' a comprehensive biosafety analysis for any plant growth-promoting bacteria (PGP bacteria) is essential, thus, Enterobacter sp. (JJG_Zn), along with two other standard cultures, Burkholderia seminalis and Stenotrophomonas maltophilia, were evaluated for biosafety tests-including sheep blood agar assay, E.coli sensitivity assay, and pathogenicity tests on albino mice. The results indicated that all three PGP bacteria were potentially innocuous and compatible with each other. Furthermore, the field experiments were conducted at Punjab Agricultural University, Regional Research Station, Bathinda, and School of Organic Farming, IFS, Punjab Agricultural University, Ludhiana during Kharif 2022 employing a randomized complete block design (RCBD) with nine treatment combinations. The treatments included liquid bacterial inoculants (LBIs) of Stenotrophomonas maltophilia, Burkholderia seminalis, and Enterobacter sp. (JJG_Zn) applied in combination with 100% and 75% of the recommended dose of fertilizer (RDF), with each treatment replicated thrice. The treatment T (75% RDF + dual inoculation with B. seminalis and S. maltophilia) resulted in the highest productivity, showing a 10.23% increase in pooled green fodder yield (GFY) compared to the control. The treatment T (75% RDF + Enterobacter sp. (JJG_Zn)) showed a 5.14% increase in productivity over the control. Thus, liquid bacterial inoculants (LBIs) present a promising approach to enhance the productivity of forage Sorghum.
Metabarcoding for the Monitoring of the Microbiome and Parasitome of Medically Important Mosquito Species in Two Urban and Semi-urban Areas of South Korea
Chavarria X, Choi JH, Oh S, Kim M, Kang D, Lee IY, Jang YS, Yi MH, Yong TS and Kim JY
Interactions between microbial communities and the host can modulate mosquito biology, including vector competence. Therefore, future vector biocontrol measures will utilize these interactions and require extensive monitoring of the mosquito microbiome. Metabarcoding strategies will be useful for conducting vector monitoring on a large scale. We used 16S and 18S rRNA gene metabarcoding through iSeq100 sequencing to characterize the microbiome and eukaryome of Aedes albopictus (Skuse 1894) and Culex pipiens (Linnaeus 1758), two globally important vectors present in South Korea. Mosquitoes were collected from an urban and a semi-urban location in South Korea. Bacterial alpha and beta diversities varied by population. Pseudomonadota dominated the microbiomes of both species. The microbiome composition varied by population and was dominated by different taxa. At the genus level, Wolbachia sp. was the most enriched genus in Cx. pipiens, followed by Aeromonas sp. In Ae. Albopictus, the most abundant group was Enterococcus sp. The gregarine parasite Ascogregarina taiwanensis was highly prevalent in Ae. Albopictus and its absence was marked by the presence of seven bacterial taxa. To our knowledge, this is the first characterization of the microbiome of Ae. albopictus and Cx. pipiens in these regions of South Korea and contributes to the current information on the microbiome of mosquito species, which can be used in further studies to assess pathogen-microbiome and microbiome-microbiome interactions.
Effectiveness of Plant-Induced Resistance Against Root-Knot Nematode Depends on the Policy of Using Inducer on the Host Plant
Behzadian S, Sahebani N and Karimi S
This research was conducted to determine the relationship between plant defense responses and the extent of treatment applied to either the aerial parts or roots of the plant. The experimental treatments included different methods of application (spraying versus soil drenching), varying treatment areas (one-sixth, one-third, half, or all of the plant's aerial parts and roots) with SA, and infecting the plants with root-knot nematodes. Evaluation of plant growth and nematode pathogenicity indices in the greenhouse section, HO accumulation rate, and phenylalanine ammonia lyase enzyme activity (in aerial parts and roots) were carried out in biochemical experiments. The results showed that treating less than one-third of the aerial parts with salicylic acid (SA) did not significantly impact plant growth or nematode pathogenicity indices. However, it did lead to a notable increase in hydrogen peroxide (HO) accumulation, while phenylalanine ammonia lyase (PAL) enzyme activity remained unchanged. In contrast, treating more than one-third of the aerial parts resulted in decreased nematode pathogenicity and enhanced production of defense compounds. Notably, treatments targeting the roots consistently demonstrated a more pronounced effect on nematode suppression and increased defense compound levels, emphasizing the importance of root treatment, as this is where nematodes are primarily present. Overall, the study highlights the differential impact of treatment location and extent on plant defense mechanisms and suggests that strategic targeting of either aerial or root tissues can optimize plant responses against nematode attacks.
Occurrence of Antibiotic-Resistant Bacteria in Urban Surface Water Sources in Bangladesh
Islam MMM, Islam MA, Neela FA and Hasanuzzaman AFM
Infections caused by antibiotic-resistant bacteria (ARB) result in an estimated 1.27 million human deaths annually worldwide. Surface waters are impacted by anthropogenic factors, which contribute to the emergence and spread of ARB in the aquatic environment. While research on antibiotic resistance in surface waters has increased recently in developing nations, including Bangladesh, especially in aquaculture, such studies are still limited in Bangladesh compared to developed nations. In this study, bacteria strains isolated from three rivers and two lakes in Khulna city, Bangladesh were characterized for their antibiotic resistance using disk diffusion method. Of the 106 bacterial isolates from 180 surface water samples, the majority exhibited resistance to Ciprofloxacin (75.0-87.5%) and Ceftriaxone (65.6-78.1%), while resistance to Ampicillin was comparatively lower (9.4-18.8%). Notably, the prevalence of ARB was observed to be higher during the wet seasons compared to the dry seasons. The 16S rRNA gene analysis showed that Shigella flexneri was the most dominant (17.9%) bacterium among the ARB cultured from surface waters, followed by Escherichia fergusonii (12.5%), Proteus mirabilis (10.7%), and Enterobacter quasiroggenkampii (8.9%). At the genus level, Enterobacter (23.5%), Shigella (20.6%), and Escherichia spp. (14.7%) were the most abundant among the ARB in both river and lake samples. The findings of this study highlight the prevalence of antimicrobial resistance in surface water sources and suggest the need for enhanced monitoring and improved disposal practices to mitigate potential public health risks.
Characterization, Bio-Prospection, and Comparative Metagenomics of Bacterial Communities Revealing the Predictive Functionalities in Wild and Cultured Samples of Industrially Important Red Seaweed Gracilaria dura
Mathew DE, Soni A, Dhimmar A, Gajjar A, Parab AS, Phakatkar SS, Sahastrabudhe H, Manohar CS, Shinde PB and Mantri VA
The present study explores the microbial community associated with the industrially important red seaweed Gracilaria dura to determine the diversity and biotechnological potential through culture and metagenomics approaches. In the first part of the investigation, we isolated and characterized 75 bacterial morphotypes, with varied colony characteristics and metabolic diversity from the wild seaweed. Phylogenetic analysis identified isolates in Proteobacteria, Firmicutes, and Actinobacteria, with Bacillus sp. being prevalent. B. licheniformis and Streptomyces sp. were notable in producing important enzymes like L-asparaginase, and polysaccharide lyases. Antimicrobial activity was significant in 21% of isolates, effective against seaweed pathogens such as Vibrio and Xanthomonas. Rhodococcus pyridinivorans showed strong pyridine degradation, suggesting bioremediation potential. Several isolates exhibited phosphate solubilization and nitrate indicating the roles of bacteria as algal growth promoters and biocontrol agents. Subsequent metagenome analysis of wild and cultured samples provides insights into bacterial communities associated with G. dura, revealing their distribution and functional roles. Proteobacteria (~ 95%) dominated the communities, further bacterial groups involved in algal growth, carpospore liberation, stress resistance, biogeochemical cycles, and biomedical applications were identified. A notable difference in bacteriomes was observed between the samples, with 25% remaining stable. The samples are cultured in the lab to generate seedlings for farming and serve as germplasm storage during the monsoon season. Microbiome surveys are crucial for understanding the association of pathogens and the overall health of the seedlings, supporting successful seaweed farming. Our findings provide valuable insights into G. dura-associated microbial communities and their role in algal growth, which has aquacultural implications.
Highly Potent New Probiotic Strains from Traditional Turkish Fermented Foods
Yigit MB and Cebeci A
Traditional Turkish fermented foods like boza, pickles, and tarhana are recognized for their nutritional and health benefits, yet the probiotic potential of lactic acid bacteria (LAB) strains isolated from them remains underexplored. Sixty-six LAB strains were isolated from fermented foods using bacterial morphology, Gram staining, and catalase activity. The isolates were differentiated at strain level by RAPD-PCR (Random Amplification of Polymorphic DNA-Polymerase Chain Reaction) and twenty-five strains were selected for further evaluation of acid and bile salt tolerance. Among these, ten strains exhibited high tolerance and were subsequently assessed for adhesion to Caco-2 colorectal carcinoma cells, antimicrobial activity, exopolysaccharide (EPS) production, lysozyme resistance, and hemolytic activity. Using k-means clustering, three strains: Lactiplantibacillus plantarum ES-3, Pediococcus pentosaceus N-1, and Enterococcus faecium N-2 demonstrated superior probiotic characteristics, including significant acid (100% survival at pH3.0) and 0.3% bile salt tolerance (57%, 64%, 67%), strong adhesion to intestinal cells (65%, 88%, 91%), high lysozyme resistance (88%, 88%, 77%), and produced high amounts of EPS. These strains show promising potential as probiotics and warrant further investigation to confirm their functional properties and potential applications.
Gallibacterium faecale sp. nov., Isolated from Dairy Cow Feces
Ryu SW, Moon JC, Oh BS, Yu SY, Bak JE, Heo ES, Park SH, Kang SW, Lee J, Lee MK, Jung M, Choi YH, Kim HB, Kim JK, Lee JH and Lee JH
A facultative anaerobic, Gram-stain-negative, non-motile, rod-shaped bacterial strain AGMB14963 was isolated from the feces of a dairy cow. A 16S rRNA gene sequence-based phylogenetic analysis revealed that strain AGMB14963 belongs to the genus Gallibacterium, with Gallibacterium salpingitidis F150 being the closest species (95.8% 16S rRNA gene sequence similarity). Whole-genome sequence analysis revealed that strain AGMB14963 had a 37.0% G + C genomic DNA content and a genome size of 2.58 Mb. In addition, the strain contained 53 tRNA and 2 rRNA genes. The average nucleotide identity and digital DNA-DNA hybridization values between strains AGMB14963 and G. salpingitidis F150 were 82.3 and 24.9%, respectively. Further, strain AGMB14963 was positive for oxidase and catalase, but negative for urease. Optimal growth of strain AGMB14963 occurred at 37 ℃, pH 8, and in 0.5% NaCl-containing medium. The predominant cellular fatty acids (> 10%) in strain AGMB14963 were C, C, and summed feature 3. Strain AGMB14963 produced lactic acid and isobutyric acid as the major end products of glucose fermentation. Polar lipids consisted of one phospholipid and one phosphoaminolipid. According to the genomic, physiologic, and chemotaxonomic characteristics, strain AGMB14963 represents a novel species of the genus Gallibacterium, for which the name Gallibacterium faecale sp. nov. is proposed. The type strain is AGMB14963 (= KCTC 25487 = NBRC 116419).
Cellulases Production by Aspergillus unguis in Solid State Fermentation and Enzymatic Hydrolysis of Dilute Acid-Treated Groundnut Fodder
Chandra MRGS, Shruthi K, Sivaprasad BV, Chandrasekhar T, Rao KM, Maddela NR and Prasad R
Groundnut fodder was utilized as a bioresource for the production of cellulases through solid state fermentation (SSF). Aspergillus unguis was initially grown on modified groundnut fodder for cellulase production and the fodder was hydrolyzed by the crude cellulase extract into fermentable hydrolyzate. The highest titer of Filter paperase (FPase), Carboxymethyl cellulase (CMCase), β-glucosidase, and protein content were found to be 11.4, 11.5, 33.3 U/g, and 136.6 mg/g of substrate, respectively. Treatment of groundnut fodder with dilute acid and supplementation of mineral salts, and yeast extract (5% w/v) enhanced cellulase production. The hydrolysis of modified groundnut fodder treated with Tween-80 using the crude cellulase extract resulted in increased production of reducing sugars (40%) at 50 °C compared with control. In conclusion, the addition of Tween-80 at pH 4.8 increased a twofold increase in the yield of reducing sugar.
Antimicrobial and Cytotoxic Potential of Endophytic Aspergillus versicolor Isolate from the Medicinal Plant Plectranthus amboinicus
Manaswini S, Akshata R, Bhoomika V, Nandini P, Ganapathy K and Deeshma KP
Endophytic fungi are non-pathogenic organisms that colonise healthy plant tissues asymptomatically. Endophytes derived from medicinal plants are sources for identifying natural products and bioactive compounds with potential uses for industry, medicine, agriculture, and related sectors. In the present study, ethyl acetate crude extracts of four endophytic fungal isolates (CALF1, CALF4, and CASF1) from the medicinal plant Plectranthus amboinicus showed potent antimicrobial activity against the test pathogenic bacteria Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis using disc diffusion assays. A colorimetric microdilution assay to detect the minimum inhibitory concentration (MIC) revealed that the extracellular extract (ECE) of CASF1 isolate had the lowest MIC values against the test pathogenic bacteria (0.19-6.25 mg/ml) compared to other CALF1 and CALF4. Cytotoxic activity of CASF1-ECE against the drug-resistant KB.CHR.8-5 cancer cell line tested by the MTT assay showed complete cell death at a concentration of 220 μg/mL and the half-maximum inhibitory concentration (IC) was determined to be 77.9 ± 09 μg/mL. GC-MS analysis showed hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester, as the dominant compound among the bioactive compounds identified in the EXE of CASF1 isolate, with the highest peak in the GC chromatogram, indicating its role in the antimicrobial and cytotoxic activity of CASF1. Molecular identification of CASF1 using 18S rRNA sequencing and BLAST analysis detected CASF1 as an isolate of Aspergillus versicolor with 100% sequence identity.
From Farm to Community: Dispersal of Potentially Pathogenic Staphylococcus and Mammaliicoccus Species and Antimicrobial Resistance Across Shared Environments
Ahmad F, Martuchelle SS, Andrade-Oliveira AL, Lanes Viana VE, Sousa MASM, da Silveira FS, Nogueira-Diaz MA, Pereira MF, Giambiagi-deMarval M and Rossi CC
Staphylococcaceae are a diverse bacterial family with important implications for human and animal health. This study highlights the One Health relevance of their environmental dispersal, particularly, by identifying closely related or genetically identical strains circulating between farm and community environments. Environmental Staphylococcaceae strains were isolated from animal farms and interconnected areas within a university setting, both influenced by anthropogenic activities. Genetic diversity analysis via GTG-PCR revealed that specific strains circulated across these environments, likely facilitated by human interaction, supporting the potential for cross-environmental bacterial transfer. The strains were further tested for antimicrobial resistance against a panel of antibiotics, biofilm formation, and the presence of resistance-associated genes. We identified a wide array of Staphylococcaceae species (n = 16), with over half being pathogenic to humans and animals, including S. aureus, S. epidermidis, S. haemolyticus, and S. saprophyticus. Notably, 55.5% of the strains exhibited multidrug resistance, and 15.9% harbored the methicillin resistance gene mecA, underscoring the challenges these infections might pose to treatment. Biofilm-forming capabilities further enhance the environmental persistence of these strains. These findings underscore the critical need for surveillance and targeted intervention strategies in a One Health framework to mitigate antimicrobial resistance across shared environments.