Bioprospecting of <Emphasis Type="Italic">Diaporthe terebinthifolii</Emphasis> LGMF907 for antimicrobial compounds

Antibiotic-resistant bacteria have been observed with increasing frequency over the past decades, driving the search for new drugs and stimulating the interest in natural products sources. Endophytic fungi from medicinal plants represent a great source of novel bioactive compounds useful to pharmaceutical and agronomical purposes. Diaporthe terebinthifolii is an endophytic species isolated from Schinus terebinthifolius, a plant used in popular medicine for several health problems. The strain D. terebinthifolii LGMF907 was previously reported by our group to produce secondary metabolites with biological activity against phytopathogens. Based on these data, strain LGMF907 was chosen for bioprospecting against microorganisms of clinical importance and for characterization of major secondary metabolites. In this study, different culture conditions were evaluated and the biological activity of this strain was expanded. The crude extracts demonstrated high antibacterial activity against Escherichia coli, Micrococcus luteus, Saccharomyces cerevisiae, methicillin-sensitive Staphylococcus aureus, and methicillin-resistant S. aureus. The compounds diaporthin and orthosporin were characterized and also showed activity against the clinical microorganisms evaluated. This study discloses the first isolation of diaporthin and orthosporin from D. terebinthifolii, and revealed the potential of this endophytic fungus to produce secondary metabolites with antimicrobial activity.     

Synthesis of functionalized benzo[<Emphasis Type="Italic">f</Emphasis>]2<Emphasis Type="Italic">H</Emphasis>-chromenes and evaluation of their antimicrobial activities

Knoevenagel cyclocondensations of α-hydroxy naphthaldehyde with β-oxodithioesters and ketene dithioacetals yielded 2H-benzo[f]chromene-2-thiones and 2H-benzo[f]chromen-2-ones, respectively, in high yields. The newly synthesized compounds were evaluated for antifungal and antibacterial activities. Among them, compounds (2-furyl)(3-thioxo-3H-benzo[f]chromen-2-yl)methanone and phenyl(3-oxo-3H-benzo[f]chromen-2-yl)methanone exhibited excellent antifungal activity against tested fungi Curvularia lunata and Fusarium moniliforme. The highest antibacterial activity against the tested bacteria Escherichia coli and Staphylococcus aureus was observed for (4-chlorophenyl)(3-oxo-3H-benzo[f]chromen-2-yl)methanone. The results of antimicrobial screening demonstrate that (2-furyl)(3-thioxo-3H-benzo[f]chromen-2-yl)methanone, phenyl(3-oxo-3H-benzo[f]chromen-2-yl)methanone, and (4-chlorophenyl)(3-oxo-3H-benzo[f]chromen-2-yl)methanone are promising as antimicrobial drugs.     

The characterization of anti-<Emphasis Type="Italic">T. cruzi</Emphasis> activity relationships between ferrocenyl,cyrhetrenyl complexes and ROS release

Trypanosoma cruzi (T. cruzi) is the parasite that causes Chagas disease. Nifurtimox is the most used drug against the T. cruzi, this drug increases intermediaries nitro group, being mainly responsible for the high toxicity component, for this reason it is important to study new organic compounds and thus improve therapeutic strategies against Chagas disease. The electronic effects of ferrocenyl and cyrhetrenyl fragments were investigated by DFT calculation. A close correlation was found between HOMO–LUMO gap of nitro radical NO ₂ ^? with the experimental reduction potential found for nitro group and IC₅₀ of two forms the T. cruzi (epimastigote and trypomastigote). The IC₅₀ on human hepatoma cells is higher for both compounds compared to IC₅₀ demonstrated in the two forms the T. cruzi, and additionally show reactive oxygen species release. The information obtained in this paper could generate two new drugs with anti-T. cruzi activity, but additional studies are needed.     

Effect of selenium-containing biocomposites based on <Emphasis Type="Italic">Ganoderma</Emphasis> mushroom isolates grown in the presence of oxopropyl-4-hydroxycoumarins,on bacterial phytopathogens

Effect of selenium-containing biocomposites obtained from submerged cultures of macrobasidiomycetes Ganoderma applantum, G. cattienensis, G. colossus G. lucidum, G. neojaponicum, and G. valesiacum, on plant pathogenic bacteria Clavibacter michiganensis ssp. sepedonicus (Cms), Micrococcus luteus, Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, Pseudomonas fluorescens, Pseudomonas viridiflava, and Xanthomonas campestris was studied. Oxopropyl-4-hydroxychromenones were used as components of the fungal nutrient media. The bacteriostatic and bactericidal activity of the Se-containing and Se-free substances of fungal origin against plant pathogenic bacteria was determined using colony-forming units count, the agar well diffusion method, and by turbidity measurements of bacterial suspensions. The composites produced from the extracellular metabolites of G. cattienensis SIE1302 with 4-hydroxy-3-(3-oxo-1,3-diphenyl propyl)-chromen-2-one (S(45)), and of G. lucidum SIE1303 with 4-hydroxy-3-(3-oxo-1-(3-nitrophenyl)-3-phenylpropyl)-chromen-2-one (S(NO₂)) possessed the most pronounced antibacterial action against Cms. The composites produced from the isolates of G. valesiacum 120702 with S(NO₂) showed the maximal antibacterial activity against Xanthomonas campestris B-610. High antimicrobial effect of G. lucidum 1315 with S(NO₂) against Xanthomonas campestris B-610 and of G. colossus SIE1301 against Pseudomonas fluorescens EL-2.1 was revealed. The pioneering information on the biological activity of coumarin series compounds in their application for producing the substances of fungal origin was obtained.     

<Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> as a Probiotic Potential from Kouzeh Cheese (Traditional Iranian Cheese) and Its Antimicrobial Activity

The aim of this study is to isolate and identify Lactobacillus plantarum isolates from traditional cheese, Kouzeh, and evaluate their antimicrobial activity against some food pathogens. In total, 56 lactic acid bacteria were isolated by morphological and biochemical methods, 12 of which were identified as Lactobacillus plantarum by biochemical method and 11 were confirmed by molecular method. For analyzing the antimicrobial activity of these isolates properly, diffusion method was performed. The isolates were identified by 318 bp band dedicated for L. plantarum. The isolated L. plantarum represented an inhibitory activity against four of the pathogenic bacteria and showed different inhibition halos against each other. The larger halos were observed against Staphylococcus aureus and Staphylococcus epidermidis (15 ± 0.3 and 14.8 ± 0.7 mm, respectively). The inhibition halo of Escherichia coli was smaller than that of other pathogen and some L. plantarum did not show any inhibitory activity against E. coli, which were resistant to antimicrobial compounds produced by L. plantarum. The isolated L. plantarum isolates with the antimicrobial activity in this study had strong probiotic properties. These results indicated the nutritional value of Kouzeh cheese and usage of the isolated isolates as probiotic strains.     

Purification and characteristics of a novel bacteriocin produced by <Emphasis Type="Italic">Enterococcus faecalis</Emphasis> L11 isolated from Chinese traditional fermented cucumber

Objective

To purify and characterize a novel bacteriocin with broad inhibitory spectrum produced by an isolate of Enterococcus faecalis from Chinese fermented cucumber.

Results

E. faecalis L11 produced a bacteriocin with antimicrobial activity against both Escherichia coli and Staphylococcus aureus. The amino acid sequence of the purified bacteriocin, enterocin L11, was assayed by Edman degradation method. It differs from other class II bacteriocins and exhibited a broad antimicrobial activity against not only Gram-positive bacteria, including Bacillus subtilis, S. aureus, Listeria monocytogenes, Sarcina flava, Lactobacillus acidophilus, L. plantarum, L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. bulgaricus and Streptococcus thermophilus, but also some Gram-negative bacteria including Salmonella typhimurium, E. coli and Shigella flexneri. Enterocin L11 retained 91 % of its activity after holding at 121 °C for 30 min. It was also resistant to acids and alkalis.

Conclusions

Enterocin L11 is a novel broad-spectrum Class II bacteriocin produced by E. faecalis L11, and may have potential as a food biopreservative.

     

Imidazo[4,5-<Emphasis Type="Italic">a</Emphasis>]quinindolines as highly effective antibacterial agents

Resistance to antimicrobial agents is a concern that exists globally and has a considerable impact on human and animal health, so that the discovery of new antibacterial compounds has become increasingly more important in combating infectious disease. In this paper, imidazo[4,5-a]quinindolines are introduced as new antibacterial agents against Gram-positive and Gram-negative bacteria. These pentacyclic compounds are synthesized by the reaction of N-alkyl-5-nitrobenzimidazoles with 2-(1-alkyl-1H-3-indolyl)acetonitrile under basic conditions in excellent yields. The structures of newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectral data. The antibacterial activities of the synthesized compounds were screened against standard strains of two Gram-positive and two Gram-negative bacteria using the broth microdilution method. Most of the compounds studied showed promising activities against both types of bacteria.     

Isolation Purification and Characterization of Antimicrobial Peptides from <Emphasis Type="Italic">Cuminum cyminum</Emphasis> L. Seeds

In this work, antimicrobial peptides from Cuminum cyminum L. seeds were isolated and purified for the first time by 50% ethanol extraction, C18 reverse phase column chromatography and ion exchange chromatography for separation different peptides fraction. Then isolated fractions were characterized by Gel electrophoresis (SDS-PAGE), high-pressure liquid chromatography and the peptides components and molecular weights were determined by liquid chromatography and mass spectrometry. The extracts were tested against some strains of bacteria (E. coli and Staphylococcus aureus) and one strain of fungi (Candida albicans) using well diffusion and broth dilution assays. The extracts from C. cyminum L. seeds demonstrated a high degree of activity (some antibacterial effect) against the bacteria strains and аntifungal activity against the Candida albicans. However, the study indicates that the crude peptide extracts from C. cyminum L. seeds have promising antimicrobial and antioxidant activities that can be harnessed as leads for potential bioactive compounds.     

Antimicrobial activities of some synthesized 1-(3-(2-methylphenyl)-4-Oxo-3<Emphasis Type="Italic">H</Emphasis>-quinazolin-2-yl-4-(substituted)thiosemicarbazide derivatives

The substituted thiosemicarbazide moiety was placed at the C-2 position and 2-methylphenyl group at N-3 position of quinazoline ring and obtained compounds were tested for their antitubercular activities and antibacterial activities against selected gram-positive and gram-negative bacteria. The target compounds 1-(3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazides were obtained by the reaction of 2-hydrazino-3-(2-methylphenyl) quinazolin-4(3H)-one with different dithiocarbamic acid methyl ester derivatives. All synthesized compounds were also screened for their antimicrobial activity against selective gram-positive and gram-negative bacteria by agar dilution method. Among the series, 1-[3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl]-4-[4-chlorophenyl]-thiosemicarbazide exhibited the most potent activity against S. typhi, E. coli, and B. subtilis, while 1-[3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl]-4-[4-nitrophenyl]-thiosemicarbazide was the most potent against E. coli, B. subtilis, P. aeruginosa, S. typhi, and S. flexneri. These two compounds exhibited the antitubercular activity at the minimum concentration (3 μg/mL) that offered potential for further optimization and development of new antitubercular agents. The obtained results demonstrated promising antimicrobial and antitubercular activities of the synthesized quinazoline compounds which could be used as new scaffolds for improving their antimicrobial activity.     

In vitro antifungal activity of metal complexes of a quaternized chitosan derivative with copper ions

Antifungal activity of synthetic metal complexes of quaternized N-(propyl) chitosan derivatives with Сu(II) against yeastlike (Saccharomyces cereviseae, Rodothorula rubra, and Candida albicans) and mycelial fungi (Fusarium oxysporum, Alternaria alternata, Cladosporium herbarum) was studied. In vitro application (at 250?500 μg/mL) of the metal complex of quaternized N-(propyl) derivative of low-molecular chitosan with 53% substitution and 1.3% copper ions proved efficient against F. оxysporum, one of ten most common fungal plant pathogens. Water-soluble quaternized N-(propyl) chitosan derivatives with 40?58% degree of substitution were synthesized using glycidyltrimethylammonium chloride under optimally adjusted conditions. Metal complexes of the chitosan derivative with 53% degree of substitution with Сu(II) ions were obtained by dialysis. The quantity of copper ions in the metal complexes was determined by atomic emission spectrometry. The structure of chitosan derivatives was confirmed by spectral analysis (IR, ¹H NMR).     

Antimicrobial Efficacy of Synthetic Pyranochromenones and (Coumarinyloxy)acetamides

Four (1, 2, 4 and 6) synthetic quaternary ammonium derivatives of pyranochromenones and (coumarinyloxy)acetamides were synthesized and investigated for their antimicrobial efficacy on MRSA (Methicillin-resistant Staphylococcus aureus), and multi-drug resistant Pseudomonas aeruginosa, Salmonella enteritidis and Mycobacterium tuberculosis H37Rv strain. One of the four compounds screened i.e. N,N,N-triethyl-10-((4,8,8-trimethyl-2-oxo-2,6,7,8-tetrahydropyrano[3,2-g]chromen-10-yl)oxy)decan-1-aminium bromide (1), demonstrated significant activity against S. aureus, P. aeruginosa and M. tuberculosis with MIC value of 16, 35, and 15.62 µg/ml respectively. The cytotoxicity evaluation of compound 1 on A549 cell lines showed it to be a safe antimicrobial molecule, TEM study suggested that the compound led to the rupture of the bacterial cell walls.     

Synthesis,characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from <Emphasis Type="Italic">Streptomyces xinghaiensis</Emphasis> OF1 strain

We report synthesis of silver nanoparticles (AgNPs) from Streptomyces xinghaiensis OF1 strain, which were characterised by UV–Vis and Fourier transform infrared spectroscopy, Zeta sizer, Nano tracking analyser, and Transmission electron microscopy. The antimicrobial activity of AgNPs alone, and in combination with antibiotics was evaluated against bacteria, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, and yeasts viz., Candida albicans and Malassezia furfur by using micro-dilution method. The minimum inhibitory concentration (MIC) and minimum biocidal concentration of AgNPs against bacterial and yeast strains were determined. Synergistic effect of AgNPs in combination with antibacterial and antifungal antibiotics was determined by FIC index. In addition, MTT assay was performed to study cytotoxicity of AgNPs alone and in combination with antibiotics against mouse fibroblasts and HeLa cell line. Biogenic AgNPs were stable, spherical, small, polydispersed and capped with organic compounds. The variable antimicrobial activity of AgNPs was observed against tested bacteria and yeasts. The lowest MIC (16 µg ml^?1) of AgNPs was found against P. aeruginosa, followed by C. albicans and M. furfur (both 32 µg ml^?1), B. subtilis and E. coli (both 64 µg ml^?1), and then S. aureus and Klebsiella pneumoniae (256 µg ml^?1). The high synergistic effect of antibiotics in combination with AgNPs against tested strains was found. The in vitro cytotoxicity of AgNPs against mouse fibroblasts and cancer HeLa cell lines revealed a dose dependent potential. The IC₅₀ value of AgNPs was found in concentrations of 4 and 3.8 µg ml^?1, respectively. Combination of AgNPs and antibiotics significantly decreased concentrations of both antimicrobials used and retained their high antibacterial and antifungal activity. The synthesis of AgNPs using S. xinghaiensis OF1 strain is an eco-friendly, cheap and nontoxic method. The antimicrobial activity of AgNPs could result from their small size. Remarkable synergistic effect of antibiotics and AgNPs offer their valuable potential in nanomedicine for clinical application as a combined therapy in the future.     

Phylogeny and bioactivity of epiphytic Gram-positive bacteria isolated from three co-occurring antarctic macroalgae

Marine macroalgae are emerging as an untapped source of novel microbial diversity and, therefore, of new bioactive secondary metabolites. This study was aimed at assessing the diversity and antimicrobial activity of the culturable Gram-positive bacteria associated with the surface of three co-occurring Antarctic macroalgae. Specimens of Adenocystis utricularis (brown alga), Iridaea cordata (red alga) and Monostroma hariotii (green alga) were collected from the intertidal zone of King George Island, Antarctica. Gram-positive bacteria were investigated by cultivation-based methods and 16S rRNA gene sequencing, and screened for antimicrobial activity against a panel of pathogenic microorganisms. Isolates were found to belong to 12 families, with a dominance of Microbacteriaceae and Micrococcaceae. Seventeen genera of Actinobacteria and 2 of Firmicutes were cultured from the three macroalgae, containing 29 phylotypes. Three phylotypes within Actinobacteria were regarded as potentially novel species. Sixteen isolates belonging to the genera Agrococcus, Arthrobacter, Micrococcus, Pseudarthrobacter, Pseudonocardia, Sanguibacter, Staphylococcus, Streptomyces and Tessaracoccus exhibited antibiotic activity against at least one of the indicator strains. The bacterial phylotype composition was distinct among the three macroalgae species, suggesting that these macroalgae host species-specific Gram-positive associates. The results highlight the importance of Antarctic macroalgae as a rich source of Gram-positive bacterial diversity and potentially novel species, and a reservoir of bacteria producing biologically active compounds with pharmacological potential.     

Calcium-dependent antibacterial activity of donkey’s milk against <Emphasis Type="Italic">Salmonella</Emphasis>

The aim of this study was to examine the antibacterial activity of raw donkey’s milk (DM) against Salmonella Enteritidis and Salmonella Typhimurium as well as to determine the dependence of this antibacterial activity on calcium, lysozyme and lactoferrin content. Antibacterial assays were conducted in DM artificially contaminated with these Salmonella serotypes and then incubated at 38 °C for 8 hours. Calcium concentration was found to have a strong influence on the antibacterial activity of the contaminated DM samples supplemented with CaCl₂ and EDTA. The antibacterial activity of DM against the tested Salmonella strains was observed to be strongly calcium dependent, with the addition of CaCl₂ to DM samples improving its antibacterial potential against both pathogens. Salmonella Enteritidis appeared to be less sensitive to the antimicrobial agents in DM than S. Typhimurium. One explanation is the calcium-dependant antibacterial activity of DM is attributable to the calcium-binding ability of its lysozyme. Lysozyme may be the main antibacterial agent, most probably via a nonenzymatic mode of action against tested Salmonella strains.     

Isolation of <Emphasis Type="Italic">Lactobacillus</Emphasis> strains from shellfish for their potential use as probiotics

Microorganisms intended for use as probiotics in aquaculture should exert antimicrobial activity and be regarded as safe not only for their aquatic hosts but also for their surrounding environments and humans. The objective of this work was to investigate antimicrobial activity against various pathogens, bile salt tolerance, and acid tolerance of 65 presumptive Lactobacillus spp. isolated from shellfish samples. Four strains (HL1, HL12, HL20, and JL28) were selected after qualitatively identifying high levels of antimicrobial activity against bacteria including Staphylococcus aureus, Salmonella typhimurium, Salmonella enteritidis, Escherichia coli O157:H7, Vibrio ichthyoenteri, Edwardsiella tarda, Streptococcus iniae, and V. parahaemolyticus. The sequence analysis of their 16S rRNA genes revealed that the four strains belong to the Lactobacillus plantarum species. In addition, their survivability was tested in bile salt and acidic conditions to show their potential use as probiotics in the gastrointestinal tract.     

Synthesis and antibacterial activity of some new benzo[5,6]chromeno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

The synthesis and antibacterial activity of some new benzo[5,6]chromeno[2,3-d]pyrimidine derivatives are described. The title compounds were obtained by the reaction of 1H-benzo[f]chromenes with aliphatic and aromatic amines. The structures of all newly synthesized compounds were confirmed by IR, ¹HNMR, ¹³C NMR, and NOESY experiments. The compounds exhibited potent antibacterial activity against gram-positive and gram-negative bacterial species. 10-Methyl-12-(4-hydroxyphenyl)-10,12-dihydro-11H-benzo[5,6]chromeno[2,3-d] pyrimidin-11-imine displayed greater antibacterial activity against gramnegative bacterial species than did ciprofloxacinandamoxicillin.     

Synthesis and Anti-Infective Activity of 2-Heteroaryl(Acyl)-9,10,12,13-Tetramethoxy-3-Methyl-4,5-Dihydro-3<Emphasis Type="Italic">H</Emphasis>-Phenanthro[1,2-<Emphasis Type="Italic">d</Emphasis>]Azepines

2-Hetaryl- and 2-acyl-9,10,12,13-tetramethoxy-3-methyl-4,5-dihydro-3H-phenanthro[1,2-d]-azepines have been synthesized from 8,9,11,12-tetramethoxy-2-methyl-3,4-dihydronaphtho[2,1-f]isoquinolinium perchlorate by pyridine-azepine recyclization. The resulting compounds have revealed a pronounced antibacterial activity against Staphylococcus aureus (strain P-209) and Escherichia coli (field strain 078). Some of these compounds have a moderate fungistatic activity against Peniciliium italicum fungi. Two compounds have shown a certain activity in relation to the Colpoda steinii protozoa.     

Oxygen tolerance in anaerobic pathogenic bacteria

A prerequisite for successful identification of anaerobic pathogenic bacteria from samples of clinical material is the method of cultivation. Currently, several methods of cultivation in anaerobic environment are used: cultivation in anaerobic box, anaerobic jar, and in nonrecurring cultivation system. Here, we determined the suitability of the above methods of cultivation using the estimation of the growth (diameters of colony size) of commonly isolated anaerobic pathogens (Bacteroides fragilis, Clostridium difficile, and Clostridium perfringens). The tested bacterial strains were exposed to atmospheric oxygen for various time periods and then they were cultivated using different anaerobic cultivation systems. Maximum growth differed, depending on the type of cultivation and the strain used. Thus, largest zone diameters, in the majority of measurements, were achieved in the anaerobic box. However, nonrecurring cultivation system seemed better in several cases; this applied to the cultivation of C. perfringens after 15, 30, and 60 min exposure to atmospheric oxygen as well as the cultivation of B. fragilis after 30 and 60 min of oxygen exposure. The cultivation in anaerobic box was the most convenient method for growth of C. difficile. In almost all cases, higher growth was observed in nonrecurring cultivation system than in the system of anaerobic jar. On the other hand, no significant differences were observed among these anaerobic cultivation systems which confirmed their applicability (taking into account some individual features concerning the optimization of cultivations) for identification of pathogenic anaerobes.     

Efficient inhibition of some multi-drug resistant pathogenic bacteria by bioactive metabolites from <Emphasis Type="Italic">Bacillus amyloliquefaciens</Emphasis> S<Subscript>5</Subscript>I<Subscript>4</Subscript> isolated from archaeological soil in Egypt

Sixty-eight bacterial cultures were isolated from 5 archaeological soils in Egypt. It is necessary to characterize bacteria from ancient temples to develop protection programs for such archaeological places. Purified bacterial cultures were then tested for their capability to inhibit some multi-drug resistant (MDR) pathogenic bacteria including Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Escherichia coli and Klebsiella pneumoniae. Among the most active 10 antibacterial isolates, only one isolate designated as S₅I₄ was selected, characterized and identified as belonging to Bacillus amyloliquefaciens. The strain identification was confirmed by amplification of its 16S rRNA gene. The partial nucleotide sequence of the amplified 16S rRNA gene of the tested strain was submitted in GenBank with accession number AB813716. The physical and nutritional parameters were optimized to improve the production of antimicrobial agents by the B. amyloliquefaciens S₅I₄. The maximum antagonistic effect of this strain against the tested MDR pathogenic bacteria was achieved in presence of 1% galactose and 0.5% yeast extract at 37°C and pH 7.0 after 48 h incubation. The antibacterial compounds of B. amyloliquefaciens S₅I₄ were extracted, purified and characterized using spectroscopic analysis (IR, UV, proton NMR and MS). The compound having inhibitory activity was identified as butanedioic acid, octadecyl,1(1carboxy1methylethyl) 4octyl ester.     

The Phenolic Contents and Antimicrobial Activities of Some Marine Algae from the Mediterranean Sea (Algeria)

In this study, three marine algae collected from western coast of algerian mediteranean sea (Ulva lactuca, Dictyota dichotoma, and Corallina elongata) were tested using the agar-well diffusion method for their production of antibacterial and antifungal agents on various organisms that cause diseases of humans and plants (Eschirichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Salmonella sp, Candida albicans, and Penicillium sp.). The total phenol content and antimicrobial activity were determined using different crude seaweeds extracts (methanol, diethylether, and chloroform). The results show that the chloroform extracts of (Ulva lactuca and Corallina elongata) had the highest activity against E. coli and Salmonella sp. The methanol extract obtained from (Ulva lactuca, Dictyota dichotoma, and Corallina elongata) showed antifungal activity for Candida albicans. The results of the study revealed that the seaweeds from Algeria appear to have immense potential as a source of antibacterial and antifungal compounds; they can be used in treating diseases caused by these organisms.