Isolation Of Endophytic Bacteria Research Articles

Antioxidant Activity of Ethyl Acetate Extract from Endohytic Bacteria of Mangosteen (Garcinia mangostana L.) Roots

Aims: This study aims to obtain isolates of endophytic bacteria found in mangosteen roots, determine information regarding the chemical contents of secondary metabolites from endophytic bacteria, and obtain antioxidant activity data using the DPPH (1,1-Diphenyl-2-Picrylhydrazyl) method. Place and Duration of Study: The research was conducted from June to September 2019 at the Microbiology Laboratory of Universitas Perintis and the Higher Education Coordinating Board Region X, West Sumatra, Indonesia. Methodology: Isolation of endophytic bacteria, secondary metabolite production by endophytic bacteria, phytochemical screening, and antioxidant activity testing using the DPPH method. Results: The results of measuring the antioxidant activity of secondary metabolite extracts from endophytic bacteria of mangosteen rootsusing the DPPH method yielded an IC50 of 14,047.912 g/ml and gallic acid solution of 2,498 g/ml. Furthermore, the T-test analysis between the % inhibition of secondary metabolites from endophytic bacteria of mangosteen roots and gallic acid yielded a significant value of 0.013. Conclusion: The antioxidant activity of secondary metabolites from endophytic bacteria of mangosteen roots is considered weak and cannot be an alternative or solution for antioxidant production.

Optimization of Sterilization Parameters for Isolation of Endophytes from Allium sativum and Exploring its Antibacterial Activity

Endophytic bacteria reside within the plant cell and are beneficial to it in a number of ways like growth, protection to environmental conditions and sustainability in favor of the hosts. Throughout the ages, Garlic (Allium sativum L.) has legendary therapeutic importance. The important step in endophyte isolation is the removal of plant tissue surface microflora, called as surface sterilization. Endophytes from medicinal plants may mimic the compound produced by the host plant and also plays an important role in production of bioactive compound, so it is necessary to isolate endophytes, not the epiphytic microbes. The present investigation was undertaken with an aim to optimize the sterilization parameters viz: time and concentration of ethanol and sodium hypochlorite for isolation of endophytic bacteria as well as exploring their antibacterial activity from Allium sativum. The results revealed that concentration and exposure time of sterilizing agent caused prominent surface sterilization but have negative effect on isolation of endophytes. Experimental results revealed that 70% ethanol (6 min), 2% sodium hypochlorite (1 min) followed by 70% ethanol (30 sec) is effective for surface sterilization of leaf and 70% ethanol (6 min), 3% sodium hypochlorite (1 min) followed by ethanol (30 sec) for bulb of Allium sativum. A total of 86 bacterial endophytes were recovered and screened for antibacterial activity against Enterococcus faecalis, Bacillus cereus ATCC 11778, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Enterobacter, Klebsiella pneumoniae, Salmonella typhi and Proteus. Out of 86 bacterial endophytes, only (9%) endophytes were found to be inhibiting one or all test human pathogen. The findings of the present study suggest that use of optimized sterilization conditions are effective for removing surface bacterial strains without affecting endophytes as well as the Allium sativum plant of the Jaunpur district represents an excellent reservoir of endophytic bacteria and novel source of bioactive compounds. On the other hand different concentration and time of their exposure to different parts of plant is required for proper surface sterilization of that part and isolation of endophytes.

Characterization of three novel stem rot pathogens and their antagonistic endophytic bacteria associated with Cistanche deserticola.

Cistanche deserticola is a precious Chinese medicinal material with extremely high health care and medicinal value. In recent years, the frequent occurrence of stem rot has led to reduced or even no harvests of C. deserticola. The unstandardized use of farm chemicals in the prevention and control processes has resulted in excessive chemical residues, threatening the fragile desert ecological environment. Therefore, it is urgent to explore safe and efficient prevention and control technologies. Biocontrol agents, with the advantages of safety and environment-friendliness, would be an important idea. The isolation, screening and identification of pathogens and antagonistic endophytic bacteria are always the primary basis. In this study, three novel pathogens causing C. deserticola stem rot were isolated, identified and pathogenicity tested, namely Fusarium solani CPF1, F. proliferatum CPF2, and F. oxysporum CPF3. For the first time, the endophytic bacteria in C. deserticola were isolated and identified, of which 37 strains were obtained. Through dual culture assay, evaluation experiment and tissue culture verification, a biocontrol candidate strain Bacillus atrophaeus CE6 with outstanding control effect on the stem rot was screened out. In the tissue culture system, CE6 showed excellent control effect against F. solani and F. oxysporum, with the control efficacies reaching 97.2% and 95.8%, respectively, indicating its great potential for application in the production. This study is of great significance for the biocontrol of plant stem rot and improvement of the yield and quality of C. deserticola.

Control of Meloidogyne javanica in banana by endophytic bacteria

Abstract The aim of this work was to evaluate the effect of 40 endophytic bacteria isolates on the control of Meloidogyne javanica in ‘Prata-Anã’ banana seedlings. Two experiments were carried out in a completely randomized design with eight replicates. In each trial, 20 bacteria isolates and control were evaluated. Bacterial suspensions were applied to substrates during the acclimatization of seedlings at 15 and 30 days. On the 31st day, seedlings were transplanted into pots and soil was infested with M. javanica egg suspension at 8 days. After 90 days, the following variables were evaluated: number of galls, egg masses, eggs per root, reproduction factor (RF), second-stage juveniles, and shoot dry matter. The results of nematological variables were submitted to Principal Components Analysis. In trial I, the variables that most contributed to data variability were as follows: number of eggs and RF. In trial II, RF had greater influence. Of the 40 isolates evaluated, 39 reduced RF, and of the 20 isolates evaluated in the first trial, all reduced the number of eggs per root. Bacillus methylotrophicus EB26, Bacillus cereus EB25, and Bacillus sp. EB37 isolates stood out in the control of nematodes, with RF reduction above 80%.

Chitinase Enzyme-Producing Endophytic Bacterias From the Roots of the Plant Gembolo (Dioscorea bulbifera): Isolation, Characterization and its Potential as an Antifungal Agent

Chitinase is an enzyme of the chitinolytic group that has many roles in agriculture, especially as an antifungal, because chitin is one of the constituent components of the fungal cell wall. This study aimed to isolate and identify endophytic bacteria from gembolo (Dioscorea bulbifera) roots and to characterize the chitinase enzyme from these endophytic bacteria to be used as an antifungal. Isolation and identification of gembolo plant root endophytic bacteria using PCR method of 16S rRNA gene amplification and sequencing. Characterization of the chitinase enzyme produced includes determining of optimum pH, temperature, and substrate UV-Vis spectrophotometer. Antagonistic test of the chitinase enzyme and endophytic bacterial isolates (isolate K4) Fusarium oxysporum. The results showed that bacterial isolate K4 had with chitinolytic index of 2.45 mm. Electrophoresis results with PCR 16s rRNA gene; the length of the amplified fragment is the position of 1300 bp. By doing the BLAST process in GenBank, the bacterial isolate has 97.93% similarity with Enterobacter cloacae. Then, this endophytic bacteria is called Enterobacter cloacae K4-G. This bacterium produced chitinase enzyme reaching maximum chitinase activity at the 38 hours with an activity of 0.0312 U/mL. The chitinase characterization results of E. cloacae K4-G showed that the optimum conditions were reached at at pH 6, temperature 45 ᵒC, and 2.5% substrate with a chitinase activity value of 0.2467 U/mL. Chitinase enzyme and bacteria Enterobacter cloacae K4-G can inhibit the growth of the fungus Fusarium oxysporum. Therefore, Chitinase from Enterobacter cloacae K4-G can be used as an antifungal pathogen in plants.
 
 Keywords: Chitinase, endophytic bacteria, Enterobacter cloacae

Exploring the antibacterial activity of endophytic bacteria from Andaliman (Zanthoxylum acanthopodium DC.) against Bacillus subtilis

Abstract. Rizqoh D, Sipriyadi, Suryani UH, Putri CN, Agustin M, Taurustya H, Lestari N, Sariyanti M. 2024. Exploring the antibacterial activity of endophytic bacteria from Andaliman (Zanthoxylum acanthopodium DC.) against Bacillus subtilis. Biodiversitas 25: 700-707. Infectious diseases are still one of the global health problems. Increasing antibiotic resistance against several pathogenic microbes causes antibiotics to be less effective in treating infectious diseases. One pathogenic bacteria that causes infection is Bacillus subtilis, which causes bacteremia, septicemia, and endocarditis. Therefore, searching for new alternative antibiotics is urgently needed to overcome bacterial resistance. Andaliman (Zanthoxylum acanthopodium DC.) extract produces antimicrobial bioactive compounds. Thus, this study aims to explore endophytic bacteria from Z. acanthopodium and determine their antibacterial activity against Bacillus subtilis. This study used a qualitative experimental method, namely isolation of endophytic bacteria, characterization of endophytic bacteria colonies and cells, antagonistic test against B. subtilis, extraction of compounds from endophytic bacteria, and determine Minimum Inhibitory Concentration (MIC) of crude extract of endophytic bacteria against B. subtilis. This study showed that 16 endophytic isolates from Z. acanthopodium could inhibit the growth of B. subtilis, and potential isolates were EA7 and EA26, which have Minimum Inhibitory Concentration (MIC) at 40%, and EB6 at 80%.

Isolation and characterization of endophytic bacteria from medicinal plants (Berberis aristata and Xanthium strumarium) for Rosemary plant growth promotion

Isolation and characterization of endophytic bacteria from medicinal plants (Berberis aristata and Xanthium strumarium) for Rosemary plant growth promotion

Efektivitas Bakteri Endofit Asal Lahan Basah untuk Menekan Penyakit Hawar Daun Bakteri (Xanthomonas oryzae) pada Padi Beras Merah (Oryza nivara L.)

Brown rice is a type of rice that has many benefits for the health of the body. The main diseases that attack many rice plants and cause a decrease in production include bacterial leaf blight (HDB) caused by the bacterium Xanthomonas oryzae. One alternative to control HDB is to use antagonistic agents, namely endophytic bacteria. This study aims to examine the ability of endophytic bacterial isolates from wetlands and the effect of application time in suppressing the intensity of bacterial leaf blight and to determine its effect on the growth of brown rice plants. There were 2 isolates of endophytic bacteria tested in this study, namely isolates of root origin (AKL) and isolates of stem origin (BLR) isolated from karamunting plants. This study used a completely randomized design (CRD) consisting of 5 treatments and 4 replications. The treatment used in this study was only the pathogen Xanthomonas Oryzae (control), soaking seeds with endophytic bacteria from roots, soaking seeds with endophytic bacteria from stems, soaking seeds + application when transplanting with endophytic bacteria from roots and seed soaking + application when transplanting Plant with stem-origin endophytic bacteria. Treatment of endophytic bacteria on brown rice seeds and application during transplanting was able to reduce the intensity of bacterial leaf blight (X. oryzae) with a disease intensity of 83% and an effectiveness of 15.6%. Treatment of endophytic bacteria on rice seeds did not inhibit seed germination and was able to increase the number of tillers, but had not been able to affect the increase in plant height.

Isolation, Identification, and Characterization of Endophytic Bacteria from Medicinally Valuable Mirabilis jalapa L.

Isolation, Identification, and Characterization of Endophytic Bacteria from Medicinally Valuable Mirabilis jalapa L.

Effect of Application of Endophytic Bacteria on the Development of Bacterial Leaf Blight Disease, Growth, and Production of Rice Plants

Bacterial leaf blight can be found in various stages of rice plant growth, so this disease can affect the growth and production of rice plants. This research aims to determine the effect of applying an endophytic bacterial formula to rice seedlings on the development of HDB disease, growth, and production of rice plants. This study used 4 isolates of endophytic bacteria (isolates BE-KH1, BE-M2, BE-M3, and BE-S5) which were formulated in coconut water waste + peptone. The results of the study showed that the application of the endophytic bacterial formula to rice seedlings was able to reduce the severity of bacterial leaf blight by 54,5 – 63,2% and had an effect on growth, full grain weight, and rice grain weight in rice plants inoculated with Xanthomonas oryzae pv. oryzae bacteria.

Antibacterial Ability of Seaweed Endophytic Bacteria (Turbinaria ornata, Sargassum crassifolium, and Sargassum polycystum) Against Skin Disease Agents

Bioactive substances that can prevent the growth of pathogenic germs can be produced by endophytic bacteria This study aims to identify seaweed endophytic bacteria (Turbinaria ornata, Sargassum crassifolium, Sargassum polycystum) and their potential antibacterial activity against skin disease agents (Staphylococcus aureus and Staphylococcus epidermidis). In February 2023 (the rainy season), seaweed was harvested from the waters off Panjang Island in Jepara Regency, Central Java, Indonesia. Endophytic bacterial isolates that had been effectively isolated and purified were directly tested for antibacterial activity. Three isolates with the best antibacterial activity were extracted using the ethyl acetate solvent. The extract samples will be put through additional antibacterial testing using the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and paper disc diffusion procedures. Using the thin layer chromatography (TLC), the class of chemical components in the extract was determined. A molecular technique based on the 16s rRNA gene (1,400 bp) was used to identify endophytic bacterial isolates. Three species of seaweed yielded 25 isolates of endophytic bacteria: 11 from T. ornata, 7 from S. crassifolium, and 7 from S. polycystum. To.09.pp, To.10.pp, and Sc.06.pp were the 3 isolates with the highest antibacterial activity in the direct challenge test. Zone of inhibition results from subsequent antibacterial testing using paper disc diffusion ranged from medium to very strong intensity. To.10.pp sample’s MIC test yielded the best results, with S. aureus and S. epidermidis concentrations of 937.5 and 1,875 µg/mL, respectively. MBC test yielded the highest findings, with S. aureus and S. epidermidis concentrations of 1,875 and 1,875 µg/mL, respectively. The To.10.pp sample yielded terpenoids, alkaloids, and flavonoids, according to TLC analysis of chemical constituent groups. Acinetobacter indicus strain 80-1-2 and Vibrio harveyi strain B14-1 were identified as potential endophytic bacteria from T. ornata, and Acinetobacter indicus strain 80-1-2 from S. crassifolium. HIGHLIGHTS Endophytic seaweed Turbinaria ornata, Sargassum crassifolium, and Sargassum polycystum showed antibacterial activity against Staphylococcus aureus ATCC 29213 and Staphylococcus epidermidis FNCC 0048 Acinetobacter indicus strain 80-1-2, and Vibrio harveyi strain B14-1 were all successfully identified by molecular analysis as potential endophytic bacteria Identification of compounds using Thin Layer Chromatography (TLC) showed the presence of terpenoids, alkaloids, and flavonoids GRAPHICAL ABSTRACT

Culturable Bacterial Endophytes of Wild White Poplar (Populus alba L.) Roots: A First Insight into Their Plant Growth-Stimulating and Bioaugmentation Potential.

The white poplar (Populus alba L.) has good potential for a green economy and phytoremediation. Bioaugmentation using endophytic bacteria can be considered as a safe strategy to increase poplar productivity and its resistance to toxic urban conditions. The aim of our work was to find the most promising strains of bacterial endophytes to enhance the growth of white poplar in unfavorable environmental conditions. To this end, for the first time, we performed whole-genome sequencing of 14 bacterial strains isolated from the tissues of the roots of white poplar in different geographical locations. We then performed a bioinformatics search to identify genes that may be useful for poplar growth and resistance to environmental pollutants and pathogens. Almost all endophytic bacteria obtained from white poplar roots are new strains of known species belonging to the genera Bacillus, Corynebacterium, Kocuria, Micrococcus, Peribacillus, Pseudomonas, and Staphylococcus. The genomes of the strains contain genes involved in the enhanced metabolism of nitrogen, phosphorus, and metals, the synthesis of valuable secondary metabolites, and the detoxification of heavy metals and organic pollutants. All the strains are able to grow on media without nitrogen sources, which indicates their ability to fix atmospheric nitrogen. It is concluded that the strains belonging to the genus Pseudomonas and bacteria of the species Kocuria rosea have the best poplar growth-stimulating and bioaugmentation potential, and the roots of white poplar are a valuable source for isolation of endophytic bacteria for possible application in ecobiotechnology.

Isolation and Molecular Identification of Indole Acetic Acid-Producing Endophytic Bacteria from Daun Dewa Plant (Gynura divaricata (L.) DC)

Indole acetic acid (IAA) is an auxin hormone that can regulate plant growth and development. Bacteria produce IAA through L-tryptophan metabolism. The purpose of this study was to determine the ability of endophytic bacteria isolated from Daun Dewa plants to produce IAA to increase the germination and growth of tomato seedlings. Isolation of endophytic bacteria was carried out by sterilizing plant surfaces. The production of IAA is done by adding L-tryptophan precursors. The results showed that there were six endophytic bacteria, and three isolates of them have the potential to produce IAA, namely: AD1.1, UD1.1, and UD2.1. The highest IAA concentration was produced by isolate AD1.1. Growth in sprouts is significantly influenced by the concentration of IAA; the higher the concentration of IAA, the longer the shoots and the roots. Based on the 16S rRNA gene sequence, these isolates belong to the genus Klebsiella.

Diversity of endophytic bacteria in different tissues of sengon (Falcataria moluccana)

Abstract. Dewi M, Rahmawati N, Rumidatul A. 2023. Diversity of endophytic bacteria in different tissues of sengon (Falcataria moluccana). Biodiversitas 24: 5747-5756. Endophytes are endosymbionts, usually bacteria or fungi, that live inside plants without causing disease. Endophytes are available in all plant species and play a role in enhancing plant resistance to insects, pathogens, and herbivores, increasing host growth, nutrient uptake, and increasing plant tolerance to abiotic stresses such as drought. The endophyte's ability to do all that is a result of the production of biological components or secondary metabolites, which may be the result of co-evolution or genetic transfer between endophytic microorganisms and host plants. In this study, the isolation, characterization and identification of endophytic bacteria from several different plant organs of sengon (Falcataria moluccana (Miq.) Barneby & J.W. Grimes) was carried out using the plant piece method in nutrient agar medium, and identification of selected isolates was carried out based on 16S rRNA. 16S rRNA sequencing results showed that 31 endophytic bacterial communities were successfully isolated from various parts of the sengon tree. Bacteria isolated from the stem were 3 strains, bark 7 strains, leaves 11 strains, and galls 10 strains. Molecular identification and phylogenetic analysis showed that the endophytes on the stem were Curtobacterium citreum and C. luteum, respectively. The endophytic bacteria on the bark are C. herbarum, C. luteum, C. pusillum, C. citreum and Azotobacter chroococcum. The endophytic bacteria on the leaves are A. chroococcum, C. citreum, C. herbarum and Lysinibacillus sphaericus. The endophytic bacteria in the gall are Enterobacter ludwigii, Kosakonia radicincitans, Citrobacter gizzii and Erwinia endophytica.

Isolation and Identification of Endophytic Bacterial Isolates from the Leaves, Roots, and Stems Parts of Artemisia annua, Moringa oleifera, and Ocimum lamiifolium Plants.

Medicinal plants are known to harbor diverse species of endophytic bacteria which are known for secretion of beneficial secondary metabolites, like enzymes and antimicrobial compounds. The present study aimed to isolate, characterize, and identify the endophytic bacteria isolates from Artemisia annua, Moringa oleifera, and Ocimum lamiifolium plants. Certain endophytic bacterial isolates were screened. Phosphate and Zinc solubilization were performed for newly obtained isolates. The 16S rRNA gene sequencing was performed for RPAAI-8 isolate. Data were analyzed. Our study showed that endophytic bacterial isolates were recognized to be Bacillus cereus, B. subtilis, Citrobacter freundii, Enterobacter asburiae, E. cloacae, E. kobei, E. ludwigii, Enterococcus faecium, and Pseudomonas monteilli. From among these differentiated endophytic bacterial isolates, Enterobacter species are the most frequently obtained isolates. These bacterial isolates were shown 99.77% sequence similarity to Enterobacter ludwigii EN-119T (JTLO01000001) using 16S rRNA gene sequencing. This isolate was designated as Enterobacter sp. RPAAI-8. This isolate was able to employ selected cheap and cost-effective agro wastes as a carbon source. This cheap agro waste utilization by these Enterobacter species could be the first report. In conclusion, the present isolates are found to be employed for plant growth promotion and solubilizing insoluble phosphate and zinc. Before this time, most of the recent isolates were not identified from these medicinal plants. The ethyl acetate extract of the isolates also showed inhibitory activity against selected test pathogens.

Isolation and identification of endophytic bacteria and associated compound from Gloriosa superba and their antibacterial activities

Gloriosa superba L., which belongs to the genus Gloriosa and family Colchicaceae, is a climbing annual herb and tuberous poisonous tropical medicinal plant. This study was aimed to isolate possible endophytic bacteria from leaves, stems and tubers of Gloriosa superba. Thirty pure endophytic bacteria were isolated and subjected to biochemical characterization. Bacterial identification was conducted by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The structure of the isolated compound was characterized. The antibacterial activity was also evaluated. Majority (21, 70 %) of the isolates were Gram-positive. Certain of them are spore formers. Based on MALDI-TOF MS, 26 of the isolates were identified as Bacillus spp. (65.4 %), Escherichia spp. (30.8 %) and Providencia spp. (3.9 %). A 1-undecene was isolated from culture filtrate of E. coli (GST-5). The ethyl acetate extracts (1000 μg/mL) of GSL-5 and GST-2 culture filtrates recorded maximum inhibition zone against E. coli (9.4 ± 0.6 mm) and S. aurous ATCC 25923T (8.4 ± 0.8 mm), respectively. The Pseudomonas aeruginosa ATCC 27853T was prone to all ethyl acetate extracts. A 1-undecene showed a moderate activity against E. coli ATCC 25922Tand P. aeruginosa ATCC 27853T at 50 μg/mL. The present finding would be a breakthrough to studies of similar works in Ethiopia since it may be for the first time.

First report on Bacillus subtilis EU-WG-01 endophytic bacterium from wheat grass and development of probiotic formulation

Wheat grass, one of the members of Poaceae family, has been examined for therapeutic drugs efficiently. Wheat grass juice has become a popular beverage in various countries. Wheat grass is low in calories but high in nutrients, including antioxidants such as glutathione, vitamin C, and vitamin E. The juice is extracted from shoots of tender wheat grass and is an intensive source of minerals, vitamins, chlorophylls, antioxidants, polyphenols and active enzymes. The present investigation deals with the isolation of endophytic bacteria from wheat grass and development of probiotic formulation. A total of 25 endophytic bacteria were isolated from wheat grass and screened for pigment and hydrolytic enzyme production. The selected bacterial strains were screened for antimicrobial activity against pathogenic organisms Bacillus cereus (MTCC-430), E. coli (MTCC-1687) and Yersinia sp. (MTCC-4912). The efficient bacterial strain EU-WG-01 was identified using 16S rRNA gene sequencing as Bacillus subtilis. Bacillus subtilis EU-WG-01 was inoculated into mango juice to prepare a probiotic formulation. Bacillus subtilis EU-WG-01 at concentration of 15% was used to ferment the probiotic drink. The physiochemical (Total soluble sugars, reducing/non-reducing sugars, titratable acidity, antioxidant activity, protein content, color attributes and ascorbic acid), biomass and cell viable count were analysed. Among the physiochemical parameters a significant decrease was observed in total soluble sugar from 15.68°brix to 16.51°brix, total sugars from 13.30% to 7.50%, non-reducing sugars reduced from 10.20% to 1.30%, ascorbic acid from 21.60/100 mg mL−1 to 14.90/100 mg mL−1. The antioxidant activity from 6.55% to 3.56% except for titratable acidity and reducing sugars increased significantly during 30 days storage under refrigeration. Bacillus subtilis EU-WG-01 viability was found to remain well above 2 log CFU/mL−1 for 30 days. Bacillus subtilis EU-WG-01 could be used for probiotic formulation for human health.

An endophytic Paenibacillus polymyxa hg18 and its biocontrol potential against Fusarium oxysporum f. sp. cucumerinum

Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum is a serious fungal, soil-borne disease that has a dramtic negative impact on the yield and quality of cucumber. In this study, isolates of endophytic bacteria isolated from healthy cucumber plants were evaluated for their ability to inhibit Fusarium wilt. Results indicated that 6 out of 100 of the obtained endophytic bacterial isolates exhibited significant inhibitory activity against mycelial development of F. oxysporum f. sp. cucumerinum, with an inhibition rate > 60 % in dual culture assays. Among the active isolates, strain hg18 exhibited the strongest activity with a 69.57 % rate of inhibition. Strain hg18 was identified as Paenibacillus polymyxa based on morphological, physiological, and biochemical traits, as well as a phylogenetic tree that was constructed using 16S rRNA and rpoB gene sequences. Biological and PCR assays demonstrated that strain hg18 can secrete IAA, a siderophore, hydrolytic enzymes, including protease, cellulase and glucanase, and antimicrobial compounds, such as iturin, fengycin, and non-ribosomal polypeptide synthase, as well as fix nitrogen. Strain hg18 decreased the disease index of cucumber Fusarium wilt and promoted cucumber growth in non-diseased plants in greenhouse experiments, compared to a water treatment. These findings demonstrate the potential of using P. polymyxa hg18 as a biocontrol agent for controlling Fusarium wilt in cucumber.

Antibiotic- and metal-resistant endophytes inhabit Armeria maritima hyperaccumulator

Abstract Background and aims Recent research has recognized the presence of metal-resistant bacteria in plants and their role in phytoremediation intensification. However, information on the antibiotic resistance profile of those bacteria remains scarce. This study, describes the first isolation of endophytic bacteria from green parts of Armeria maritima growing on mine-tailing soil in southern Poland, and presents the resistance profile of these microorganisms. Methods Bacteria were isolated from internal tissues of Armeria maritima and characterized. Minimal Inhibitory Concentration (MIC) of metals was determined by the plate dilution method using (CH3COO)2Pb and ZnSO4 supplemented medium; antibiotic susceptibility was determined by disk diffusion method according to EUCAST version 11.0; the whole genome sequencing was performed using the MiSeq platform (Illumina). The physicochemical properties of soil were evaluated according to European Standards. Results Toxic metal-resistant bacteria were isolated from the green parts of Armeria maritima. The endophytes were identified as Pseudomonas spp. The annotated bacterial genomes carried genes encoding numerous metal ion transporters, metal reducing enzymes and efflux pump components. The bacteria were resistant to streptomycin, fosfomycin and ß-lactams. Moreover, genome analysis revealed the presence of MacAB-TolC efflux pump genes conferring resistance to macrolides, the multidrug efflux pumps AcrAB-TolC and MexAB-OprM. Conclusion Armeria maritima is inhabited by endophytic bacteria identified as Pseudomonas species that are resistant to metals and to antibiotics. Under the One Health concept the contamination of soil and plants with ARB and ARGs should be monitored and limited and a regulatory framework for safety use of bacterial bioinoculants should be established.

Screening for endophytic bacteria from Ambon Banana (Musa paradisiaca) as biocontrol agent of anthracnose (Colletotrichum gloeosporioides) on bananas fruit

Abstract. Pangastuti A, Pratiwi H, Setyaningsih R. 2023. Screening for endophytic bacteria from Ambon Banana (Musa paradisiaca L.) as biocontrol agent of anthracnose (Colletotrichum gloeosporioides) on bananas fruit. Nusantara Bioscience 15: 238-244. Post-harvest Ambon Bananas (Musa paradisiaca L.) are sensitive to anthracnose disease, caused by Colletotrichum gloeosporioides, and causes the fruit to rot quickly. Thus, chemical fungicides are employed, damaging living organisms and the environment. One solution is biocontrol using endophytic microorganisms as antagonistic agents against the anthracnose fungus that causes anthracnose disease. This study aimed to obtain potential endophytic bacteria from the Ambon Banana plant that had inhibitory activity against the growth of the pathogenic fungus C. gloeosporioides that causes anthracnose in bananas. Endophytic bacteria were recovered from Ambon Banana roots by crushing plant components. Therefore, bacterial isolates were tested for antagonistic interactions with pathogenic fungi using the dual culture approach. The 16S rRNA gene sequence analysis was used to identify bacterial isolates with the most significant inhibitory potential. According to the findings of this study, seven isolates of endophytic bacteria, A2-1, A2-2, A5-2, A6-2, A6-3, A8-1, and A9-1, can limit the growth of the pathogenic fungus C. gloeosporioides. The strain A6-3, identified as Pseudomonas pseudoalcaligenes, exhibited the greatest potential as a biocontrol agent against the pathogenic fungus C. gloeosporioides. It achieved the highest inhibition rate of 43.59%, resulting in an extended fruit shelf life and reduced harm susceptibility.