Source Of Antimicrobial Compounds Research Articles

Antibacterial Properties of Bacterial Endophytes Isolated from the Medicinal Plant Origanum heracleoticum L.

Bacterial endophytic communities associated with medicinal plants synthesize a plethora of bioactive compounds with biological activities. Their easy isolation and growth procedures make bacterial endophytes an untapped source of novel drugs, which might help to face the problem of antimicrobial resistance. This study investigates the antagonistic potential of endophytic bacteria isolated from different compartments of the medicinal plant O. heracleoticum against human opportunistic pathogens. A panel of endophytes was employed in cross-streaking tests against multidrug-resistant human pathogens, followed by high-resolution chemical profiling using headspace-gas chromatography/mass spectrometry. Endophytic bacteria exhibited the ability to antagonize the growth of opportunistic pathogens belonging to the Burkholderia cepacia complex (Bcc). The different inhibition patterns observed were related to their taxonomic attribution at the genus level; most active strains belong to the Gram-positive genera Bacillus, Arthrobacter, and Pseudarthrobacter. Bcc strains of clinical origin were more sensitive than environmental strains. Cross-streaking tests against other 36 human multidrug-resistant pathogens revealed the highest antimicrobial activity towards the Coagulase-negative staphylococci and Klebsiella pneumoniae strains. Interestingly, strains of human origin were the most inhibited, in both groups. Concerning the production of volatile organic compounds (VOCs), the strain Arthrobacter sp. OHL24 was the best producer of such compounds, while two Priestia strains were good ketones producers and so could be considered for further biotechnological applications. Overall, this study highlights the diverse antagonistic activities of O. heracleoticum-associated endophytes against both Bcc and multidrug-resistant (MDR) human pathogens. These findings hold important implications for investigating bacterial endophytes of medicinal plants as new sources of antimicrobial compounds.

The Mediterranean Zoanthid Parazoanthus axinellae as a Novel Source of Antimicrobial Compounds

Marine bioprospecting is a dynamic research field that explores the oceans and their biodiversity as noteworthy sources of new bioactive compounds. Anthozoans are marine animals belonging to the Cnidaria phylum characterized by highly specialized mechanosensory cells used both for defence against predators and prey capture. Here, high concentration of cnidocysts have been isolated from the Mediterranean zoanthid coral Parazoanthus axinellae (Schmidt, 1862) and their antimicrobial potential has been investigated. The cnidocyst extract exerted significant antibacterial activity against some human pathogens capable of developing resistance to conventional antibiotics such as Streptococcus agalactiae and Coccus sp., and against several Vibrio species, including some microbial strains for humans and farmed fish, such as Vibrio alginolyticus, Vibrio anguillarum, Vibrio fischeri, Vibrio harveyi, and Vibrio vulnificus. Results have been discussed in light of both the ecological aspects and biotechnological value of the cnidocyst extract in the nutritional, nutraceutical, and pharmaceutical fields.

Novel strains of Actinobacteria associated with neotropical social wasps (Vespidae; Polistinae, Epiponini) with antimicrobial potential for natural product discovery.

Antimicrobial resistance has been considered a public health threat. The World Health Organization has warned about the urgency of detecting new antibiotics from novel sources. Social insects could be crucial in the search for new antibiotic metabolites, as some of them survive in places that favor parasite development. Recent studies have shown the potential of social insects to produce antimicrobial metabolites (e.g. ants, bees, and termites). However, most groups of social wasps remain unstudied. Here, we explored whether Actinobacteria are associated with workers in the Neotropical Social Wasps (Epiponini) of Costa Rica and evaluated their putative inhibitory activity against other bacteria. Most isolated strains (67%) have antagonistic effects, mainly against Bacillus thuringensis and Escherichia coli ATCC 25992. Based on genome analysis, some inhibitory Actinobacteria showed biosynthetic gene clusters (BGCs) related to the production of antimicrobial molecules such as Selvamycin, Piericidin A1, and Nystatin. The Actinobacteria could be associated with social wasps to produce antimicrobial compounds. For these reasons, we speculate that Actinobacteria associated with social wasps could be a novel source of antimicrobial compounds, mainly against Gram-negative bacteria.

Streptomyces as a promising biological control agents for plant pathogens.

Plant diseases caused by pathogenic microorganisms in agriculture present a considerable obstacle, resulting in approximately 30-40% crop damage. The use of conventional techniques to manage these microorganisms, i.e., applying chemical pesticides and antimicrobials, has been discovered to have adverse effects on human health and the environment. Furthermore, these methods have contributed to the emergence of resistance among phytopathogens. Consequently, it has become imperative to investigate natural alternatives to address this issue. The Streptomyces genus of gram-positive bacteria is a potentially viable natural alternative that has been extensively researched due to its capacity to generate diverse antimicrobial compounds, such as metabolites and organic compounds. Scientists globally use diverse approaches and methodologies to extract new bioactive compounds from these bacteria. The efficacy of bioactive compounds in mitigating various phytopathogens that pose a significant threat to crops and plants has been demonstrated. Hence, the Streptomyces genus exhibits potential as a biological control agent for combating plant pathogens. This review article aims to provide further insight into the Streptomyces genus as a source of antimicrobial compounds that can potentially be a biological control against plant pathogens. The investigation of various bioactive compounds synthesized by this genus can enhance our comprehension of their prospective utilization in agriculture.

Purification and biological analysis of antimicrobial compound produced by an endophytic Streptomyces sp.

Fungal phytopathogens and drug-resistant bacteria are two significant challenges in agriculture and public health, respectively. As a result, new sources of antimicrobial compounds are urgently needed. Taking into consideration these aspects, the present study was carried out to explore the antimicrobial activity of Streptomyces sp. SP5 against drug-resistant bacteria, especially methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus and fungal phytopathogens. MRSA and VRE are both types of antibiotic-resistant bacteria that pose significant challenges to public health. In vitro analysis of the metabolites of Streptomyces sp. SP5 exhibited broad-spectrum antimicrobial activity against drug-resistant bacteria and phytopathogenic fungi. Further chemical investigation of the diethyl ether extract led to the isolation and purification of an antimicrobial compound. The structure of the purified compound was elucidated by performing detailed spectroscopic analysis including MS, IR, and NMR. The compound was identified as plicacetin. Plicacetin is a nucleoside antibiotic that has been reported for antibacterial activity against Gram-positive bacterium Mycobacterium tuberculosis. According to our knowledge, the present study is the first to demonstrate the antimicrobial properties of plicacetin against Fusarium oxysporum, Alternaria brassicicola, Fusarium solani, VRE and Bacillus subtilis. The outcome of the current study endorses that compound produced by Streptomyces sp. SP5 can be used as an antimicrobial agent against fungal phytopathogens and drug-resistant bacteria.

Natural Compounds of Fungal Origin with Antimicrobial Activity-Potential Cosmetics Applications.

The phenomenon of drug resistance in micro-organisms necessitates the search for new compounds capable of combating them. Fungi emerge as a promising source of such compounds as they produce a wide range of secondary metabolites with bacteriostatic or fungistatic activity. These compounds can serve as alternatives for commonly used antibiotics. Furthermore, fungi also accumulate compounds with antiviral activity. This review focuses on filamentous fungi and macrofungi as sources of antimicrobial compounds. The article describes both individual isolated compounds and extracts that exhibit antibacterial, antifungal, and antiviral activity. These compounds are produced by the fruiting bodies and mycelium, as well as the biomass of mycelial cultures. Additionally, this review characterizes the chemical compounds extracted from mushrooms used in the realm of cosmetology; specifically, their antimicrobial activity.

Comparison of assembly platforms for the assembly of the nuclear genome of Trichoderma harzianum strain PAR3

BackgroundTrichoderma is a diverse genus of fungi that includes several species that possess biotechnological and agricultural applications, including the biocontrol of pathogenic fungi and nematodes. The mitochondrial genome of a putative strain of Trichoderma harzianum called PAR3 was analyzed after isolation from the roots of Scarlet Royal grapevine scion grafted to Freedom rootstock, located in a grapevine vineyard in Parlier, CA, USA. Here, we report the sequencing, comparative assembly, and annotation of the nuclear genome of PAR3 and confirm its identification as a strain of T. harzianum. We subsequently compared the genes found in T. harzianum PAR3 to other known T. harzianum strains. Assembly of Illumina and/or Oxford Nanopore reads by the popular long-read assemblers, Flye and Canu, and the hybrid assemblers, SPAdes and MaSuRCA, was performed and the quality of the resulting assemblies were compared to ascertain which assembler generated the highest quality draft genome assembly.ResultsMaSuRCA produced the most complete and high-fidelity assembly yielding a nuclear genome of 40.7 Mb comprised of 112 scaffolds. Subsequent annotation of this assembly produced 12,074 gene models and 210 tRNAs. This included 221 genes that did not have equivalent genes in other T. harzainum strains. Phylogenetic analysis of ITS, rpb2, and tef1a sequences from PAR3 and established Trichoderma spp. showed that all three sequences from PAR3 possessed more than 99% identity to those of Trichoderma harzianum, confirming that PAR3 is an isolate of Trichoderma harzianum. We also found that comparison of gene models between T. harzianum PAR3 and other T. harzianum strains resulted in the identification of significant differences in gene type and number, with 221 unique genes identified in the PAR3 strain.ConclusionsThis study gives insight into the efficacy of several popular assembly platforms for assembly of fungal nuclear genomes, and found that the hybrid assembler, MaSuRCA, was the most effective program for genome assembly. The annotated draft nuclear genome and the identification of genes not found in other T. harzainum strains could be used to investigate the potential applications of T. harzianum PAR3 for biocontrol of grapevine fungal canker pathogens and as source of anti-microbial compounds.

Endophytic fungus isolated from Zingiber officinale Linn. var. rubrum as a source of antimicrobial compounds

Endophytic fungus isolated from Zingiber officinale Linn. var. rubrum as a source of antimicrobial compounds

Antagonistic and Antioxidant Potential of Actinomycete Isolates from Sambhar Lake

Bacterial secondary metabolites contain a diverse spectrum of biologically active compounds, including antimicrobials and antioxidants. Harnessing these products has enabled humans to fight against various diseases. But due to the overuse of antibiotics over the past few decades, many resistant strains of microbes are emerging. Therefore, there is a need to identify new sources of antimicrobial compounds. Actinomycetes are a group of bacteria known to produce antimicrobial compounds. This investigation aimed to identify, isolate and characterize actinomycetes with antimicrobial and antioxidant activity against pathogens acquired from MTCC. Sambhar Lake has a very potential group of actinomycetes producing several secondary metabolites. The study reports the antimicrobial and antioxidant potential of different extracts of actinomycetes. The sections of the actinomycetes were tested for their antagonistic activity against five pathogenic microorganisms. Antibacterial activity was reported in all five actinomycete isolates against Bacillus subtilis-MTCC 441, Escherichia coli-MTCC-1885, and Salmonella typhi-MTCC 733 but almost negligible activity against Staphylococcus aureus-MTCC 737 and Pseudomonas aeruginosa- MTCC 424 except for ACT-14 and ACT- 11. ACT14 had the highest antibacterial activity compared to all other isolates. The antioxidant capacities of all isolated extracts were evaluated for total phenols, total antioxidant activity, total reducing power, DPPH, and ABTS assays. Section of Pseudonocardia Antarctica ACT14 showed the highest (23.89±0.96) free radical scavenging of 2, 2-diphenyl1-picrylhydrazyl (DPPH), phenolic activity (194 ± 6.05) activity. This study was conducted to identify novel actinomycetes with antimicrobial properties. The sample ACT14 was found to be a novel actinomycete (Pseudonocardia Antarctica), and this isolate showed antimicrobial activity against all the test pathogenic bacteria used in the study. The culture was optimized for antimicrobial compound production. Since many pathogens tend to acquire antibiotic resistance, this study is essential as a novel source of antimicrobials that will provide a new weapon in the fight against infectious pathogens. Further purification and characterization of this compound are underway.

Sponges-associated marine bacteria as sources of antimicrobial compounds

Sponges-associated marine bacteria as sources of antimicrobial compounds

Antimicrobial activity of nudibranch Chromodoris lineolata associated bacteria against skin diseases pathogens from Jepara Coastal Waters, Indonesia

Abstract. Wijaya AP, Sabdono A, Sibero MT, Trianto A, Radjasa OK. 2022. Antimicrobial activity of nudibranch Chromodoris lineolata associated bacteria against skin diseases pathogens from Jepara Coastal Waters, Indonesia. Biodiversitas 23: 1911-1919. The emergence of multidrug-resistant (MDR) skin pathogens has caused the treatment of skin diseases to become increasingly ineffective using by conventional antibiotics. As a source of antimicrobial compounds against MDR pathogens, marine invertebrate-associated bacteria have been widely known for their valuable biological activity. Therefore, this study aims to determine the antimicrobial activity of nudibranch Chromodoris lineolata associated bacteria against various skin pathogens and to detect the presence of biosynthetic gene clusters (BGC) through a molecular approach. A total of 14 nudibranch-associated bacteria were successfully isolated from Awur Bay and Panjang Island. Antimicrobial activity screening using the agar plug method indicated that three bacterial strains showed antimicrobial activity against two skin pathogens, Propionibacterium acnes and Malassezia furfur. Based on the biochemical test, these potential strains were classified into the Terrabacteria and Proteobacteria groups. Through 16S rRNA gene sequencing, potential strains were identified as Streptomyces lateritius, Labrenzia marina, and Halomonas meridiana through 16S rRNA gene sequencing. The results of BGC detection showed the presence of a type II polyketide synthase (PKS II) biosynthetic gene cluster in Streptomyces lateritius and Labrenzia marina strains at 600bp-650bp.

Micrococcin P1 and P2 from Epibiotic Bacteria Associated with Isolates of Moorea producens from Kenya.

Epibiotic bacteria associated with the filamentous marine cyanobacterium Moorea producens were explored as a novel source of antibiotics and to establish whether they can produce cyclodepsipeptides on their own. Here, we report the isolation of micrococcin P1 (1) (C48H49N13O9S6; obs. m/z 1144.21930/572.60381) and micrococcin P2 (2) (C48H47N13O9S6; obs. m/z 1142.20446/571.60370) from a strain of Bacillus marisflavi isolated from M. producens’ filaments. Interestingly, most bacteria isolated from M. producens’ filaments were found to be human pathogens. Stalked diatoms on the filaments suggested a possible terrestrial origin of some epibionts. CuSO4·5H2O assisted differential genomic DNA isolation and phylogenetic analysis showed that a Kenyan strain of M. producens differed from L. majuscula strain CCAP 1446/4 and L. majuscula clones. Organic extracts of the epibiotic bacteria Pseudoalteromonas carrageenovora and Ochrobactrum anthropi did not produce cyclodepsipeptides. Further characterization of 24 Firmicutes strains from M. producens identified extracts of B. marisflavi as most active. Our results showed that the genetic basis for synthesizing micrococcin P1 (1), discovered in Bacillus cereus ATCC 14579, is species/strain-dependent and this reinforces the need for molecular identification of M. producens species worldwide and their epibionts. These findings indicate that M. producens-associated bacteria are an overlooked source of antimicrobial compounds.

Air Ambulance: Antimicrobial Power of Bacterial Volatiles.

We are currently facing an antimicrobial resistance crisis, which means that a lot of bacterial pathogens have developed resistance to common antibiotics. Hence, novel and innovative solutions are urgently needed to combat resistant human pathogens. A new source of antimicrobial compounds could be bacterial volatiles. Volatiles are ubiquitous produced, chemically divers and playing essential roles in intra- and interspecies interactions like communication and antimicrobial defense. In the last years, an increasing number of studies showed bioactivities of bacterial volatiles, including antibacterial, antifungal and anti-oomycete activities, indicating bacterial volatiles as an exciting source for novel antimicrobial compounds. In this review we introduce the chemical diversity of bacterial volatiles, their antimicrobial activities and methods for testing this activity. Concluding, we discuss the possibility of using antimicrobial volatiles to antagonize the antimicrobial resistance crisis.

Complete Genome Sequences of Four Putatively Antibiotic-Producing Bacteria Isolated from Soil in Arkansas, USA.

ABSTRACTSoil bacteria can be a valuable source of antimicrobial compounds. Here, we report the complete genomes of four soil bacteria that were isolated by undergraduate microbiology students as part of a course-based research experience. These genomes were assembled using a hybrid approach combining paired-end Illumina reads with Oxford Nanopore Technologies MinION reads.

Antarctic organisms as a source of antimicrobial compounds: a patent review.

Currently, antimicrobial resistance has become a global public health problem, which has made the need for new antimicrobial compounds to deal with resistant infections an emergency. However, environments that once offered so many innovative molecules, now already exhaustively exploited, do not meet this need. In this context, a geographically isolated, under-explored and extreme environment, such as Antarctica, which holds organisms with unique physiological and biochemical characteristics, assumes great importance as a potential source of new compounds with antimicrobial activity. In this patent review, we investigate the state of technological development in the field of antimicrobial compounds obtained from Antarctic organisms, highlighting the main countries and researchers active in the field, the species utilized, the compounds obtained, and their possible therapeutic applications. As results, few patent documents were found, however they encompass a wide diversity of compounds and species, indicating a great antimicrobial potential present in Antarctic biota, including compounds active against the most important human pathogenic microorganisms, such as including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp. and multi-resistant Mycobacterium tuberculosis. Furthermore, due to the increasing trend in patent applications, a significant rise in the number of patents in this area is expected in the coming years.

Phenolic Composition, Toxicity Potential, and Antimicrobial Activity of Licania rigida Benth (Chrysobalanaceae) Leaf Extracts.

This study was conducted to evaluate the phenolic composition, toxicity, and antimicrobial activity of Licania rigida Benth, an underexploited wild Licania species. L. rigida leaf fractions (ethyl alcohol and ethyl acetate) were analyzed for their phenolic compound and flavonoid total, and high-performance liquid chromatography/ultraviolet spectra chromatographic profiles. Regarding the extract biological effects, toxicity was measured by acute oral toxicity in Wistar rats, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method, and apoptosis indicators with DAPI in VERO cells, whereas well-agar diffusion and broth microdilution assays were applied to evaluate the antimicrobial ability. The phytochemical analysis resulted in significant amounts of phenolic compounds and total flavonoids in the extract and fraction, with flavonol-3-O-glycosylates as the main constituent. Regarding the extract and fraction antimicrobial activity, the results showed a significant effect against gram-positive bacteria and fungi, among which Staphylococcus epidermidis and Candida krusei displayed more susceptibility. No toxicity effects were observed in animals. Concerning the cytotoxicity assay, only the highest dose tested exhibited a minimal toxic effect on the analyzed cell lines. These results are relevant considering the increase of multiresistant microorganisms to conventional treatments applied. Therefore, investigating the pharmacological properties of the genus Licania is promising in the search for new sources of antimicrobial compounds.

Determination of Antibacterial Effect of Nannochloropsis oculata Against Some Rainbow Trout Pathogens

In this study, antibacterial activity of Nannochloropsis oculata which were grown in proper culture condition was searched with their extracts that obtain by using different solvent (methanol, ethanol, chloroform). The antibacterial effects of algal extracts were evaluated by using disc diffusion method against L. garvieae, F. psychrophilum and Y. ruckeri. As the results of the study, it was found that the chloroform extracts of N. oculata showed strong antibacterial activities, F. psychrophilum was the high resistant strain against to antibacterial effects of the extracts, L. garvieae and Y. ruckeri were the two most susceptible bacteria strains. The results confirm the possible use of N. oculata as a source of antimicrobial compounds or as a health-promoting food for aquaculture.

In vitro antimicrobial activity of Millettia laurentii De Wild and Lophira alata Banks ex C. F. Gaertn on selected foodborne pathogens associated to gastroenteritis

This study aimed at evaluating the antimicrobial potential of aqueous, ethanolic and methanolic extracts of two Cameroonian plants against selected foodborne pathogens. Bioactive compounds were extracted from Millettia laurentii De Wild seeds and Lophira alata Banks ex. C. F. Gaertn leaves using distilled water, ethanol and methanol as solvents. The extracts were tested against Escherichia coli O157, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Moraxella morganii, Salmonella enteritidis, Klebsiella pneumoniae and Listeria monocytogenes using the microdilution method. The results showed that distilled water extracted a more important mass of phytochemical compounds (18.0–24.60%) compared to ethanol (4.80–5.0%) and methanol (4.20–4.60%). All the extracts exhibited significant antimicrobial activity with MIC values ranging from 5 to 20 μg/mL for M. laurentii seeds extracts and from 1.0 to 20 μg/mL for L. alata leaves extracts. The different plant extracts were ten times less active than gentamicin. The most active extracts were obtained using ethanol as solvent and K. pneumoniae was the most resistant pathogen to all extracts (MBC>20 μg/mL). M. laurentii extracts were bactericidal against L. monocytogenes and P. mirabilis while the reference antibiotic (gentamicin) was bacteriostatic against these pathogens. The results obtained from this study suggest the studied local plant materials as a source of antimicrobial compounds which can be valorized in the medical field as substitute of antibiotics for which many microorganisms have nowadays developed resistance mechanisms. Further studies need to be performed in order to characterize and identify these antimicrobial active molecules.

Application of essential oils as antimicrobial agents against spoilage and pathogenic microorganisms in meat products

Meat and meat products are perishable products that require the use additives to prevent the spoilage by foodborne microorganisms and pathogenic bacteria. Current trends for products without synthetic preservatives have led to the search for new sources of antimicrobial compounds. Essential oils (EOs), which has been used since ancient times, meet these goals since their effectiveness as antimicrobial agents in meat and meat products have been demonstrated. Cinnamon, clove, coriander, oregano, rosemary, sage, thyme, among others, have shown a greater potential to control and inhibit the growth of microorganisms. Although EOs are natural products, their quality must be evaluated before being used, allowing to grant the Generally Recognized as Safe (GRAS) classification.The bioactive compounds (BAC) present in their composition are linked to their activity, being the concentration and the quality of these compounds very important characteristics. Therefore, a single mechanism of action cannot be attributed to them. Extraction technique plays an important role, which has led to improve conventional techniques in favour of green emerging technologies that allow to preserve better target bioactive components, operating at lower temperatures and avoiding as much as possible the use of solvents, with more sustainable processing and reduced energy use and environmental pollution. Once extracted, these compounds display greater inhibition of gram-positive than gram-negative bacteria. Membrane disruption is the main mechanism of action involved.Their intense characteristics and the possible interaction with meat components make that their application combined with other EOs, encapsulated and being part of active film, increase their bioactivity without modifying the quality of the final product.

Evaluation of Extracts of Leaves of <I>Crinum jagus</I> for Antimicrobial Properties

Plants have been used in ethno-medicine for ages in the treatment of various diseases. In the current study, the leaves of C. jagus are investigated for antimicrobial activities. The leaves were dried and extracted successively with hexane, ethylacetate and methanol. The concentrated extracts were screened for activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Klebisidlae pneumonae, Candida albicans, Aspergillus niger, Penicillium notatum and Rhizopus stolonifer at concentrations between 6.25 and 200 mg/ml using the agar diffusion method. The Minimum Inhibitory Concentration (MIC) was also determined. The percentage yields obtained were 0.92 %, 1.20 % and 25.2 % for the hexane, ethylacetate and methanol extracts respectively. The zones of inhibition of the organisms by the extracts generally increased with the concentrations. The methanol extract showed the best activity of the three extracts tested. The methanol extract had values ranging between 20 mm and 26 mm against the bacteria at 200 mg/ml. This extract also showed values between 18 mm and 20 mm against the fungi at 200 mg/ml. The lowest MICs values (of 2.5 mg/ml) were obtained against S. aureus, E. coli, B. subtilis and S. typhi. The polar constituents in the leaves of the plant are likely responsible for the antimicrobial properties observed. None of the extracts showed activity comparable to those of the standard drugs, however the methanol extract showed some potential as a source of antimicrobial compounds. 
 Keywords: Crinum jagus, antimicrobial, Agar diffusion, MIC