Isolation, Identification and Evaluation of the Plant Growth Promoting Activities of Endophytic Stenotrophomonas maltophilia to Stimulate Growth of Clover Plants under Salt Stress

Two endophytic bacterial isolates were obtained from root nodules of clover plants grown in salt affected clay soil of Egypt. The isolates were closely linked to Stenotrophomonas maltophilia strains IPR-Pv696 and 262XG2 based on the sequencing and phylogenetic analysis of 16S rRNA genes, and deposited in GenBank with accession numbers OM980221.1 (AM1) and OM980223.1 (AM2) respectively. The isolates were evaluated for their potential to promote plant growth. The results revealed that the two isolates of S. maltophilia strains (IPR-Pv696 and 262XG2) respectively exhibited production for indole-3- acetic acid (30.26 & 31.15 µg/ml), exopolysaccharides (13.57 & 13.68 g/l), nitrogen fixation activity and they solubilize the phosphate (278 & 208 mg/l) and potassium (33.5 & 32.9 µg/ml). In a field trial, these two isolates increased clover plant growth, chlorophyll, carbohydrates content and nutrients uptake while lowering proline levels. Hence this highlights its application to be exploited as biofertilizer by leading to sustainable agriculture. This could be a promising inoculant for many other crops.

Screening of Endophytic Bacteria Isolated from Weed Plant to Biocontrol Stem Rot Disease on Pitaya (Hylocereus undatus)

Abstract Endophytic bacteria from weed are emerging as valuable alternatives for biochemical pesticides in sustainable agriculture. This study aims to discover the antagonistic effects of some endophytic bacteria isolated from weed (Lactuca indica) against A. alternata, a casual of stem end rot disease of pitaya. A total of 14 endophytic bacteria were isolated and four of them presented in vitro antagonistic activity against A. alternata. Of four, strain L115 significantly inhibited the pathogenic growth with a mean inhibition diameter of 12.67 ± 0.02 mm, while the other three (strain L110, L111, and L114) showed a weak inhibition. The results indicated that strain L115 could belong to the Bacillaceae family while the other three (strain L110, L111, and L114) had characteristics of the Pseudomonadaceae family. Interestingly, strain L115 showed positive results for phosphate solubilization, indole acetic acid (IAA), and biofilm production, whereas three other strains presented weak capabilities for phosphate solubilization, biofilm production and IAA production. In addition, the filtrate of strain L115 presented antifungal activity on biocontrol tests in vitro. Especially, strain L115 significantly increased seedling biomass of pitaya and tomato compared to the control. Hence, these results suggest strain L115 has the potential to be used as biocontrol agents against A. alternata. More studies should be done in the future to evaluate their efficiency in field conditions.

Endophytic bacteria Bacillus safensis and Pseudomonas hibiscicola and their ability to increase rice seedling growth

Endophytic bacteria Bacillus safensis RS95 and Pseudomonas hibiscicola RS121 were evaluated for their ability to promote the growth of rice seedlings and produce indole-acetic acid (IAA) and siderophores and to solubilize phosphates. 'Guri' rice seeds were immersed in bacterial endophyte cell suspensions (separated and two-strain mixed), as well as in Escherichia coli DH5α, phosphate-buffered saline (PBS) and water treatments (negative controls). Seeds were sown on agar-water in Petri plates placed vertically at an angle of 65°. The ability of plant growth-promoting endophytic bacteria (PGPEB) to produce IAA and siderophores was determined by Salkowski colorimetric and chrome azurol S (CAS) assays, respectively. Mineral phosphate solubilization activity was calculated by inoculating the endophytes onto medium containing insoluble phosphate. PGPEB showed a positive effect on the growth of rice seedlings, causing a mean growth of shoots and primary-roots of 60 and 67%, respectively. Bacterial strains also showed positive traits for IAA and siderophore production, as well as phosphate-solubilization activity

In vitro screening of siderophore-producing rice root endophytic bacteria from up-land paddies in north-western Vietnam for plant growth-promoting activities

Aims@#Endophytic bacteria (EB) living inside plant tissues possess different beneficial traits including siderophore production and other plant growth-promoting (PGP) activities. Siderophore-producing EB promote host plant growth by secreting ferrum in iron-deficient conditions. This study screened 19 siderophore producers in vitro, isolated from upland rice roots grown in mountain farms of Tung Village, Nậm Có Commune, Mù Cang Chải District, Yên Bái Province, Vietnam, for PGP traits, including phosphate solubilisation, indole-3-acetic acid (IAA), ammonia, gelatinase, amylase and catalase production.@*Methodology and results@#The bacteria were identified by Matrix assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-TOF MS). All 19 isolates were identified as genera Pseudomonas, Enterobacter, Pantoe, Bacillus, Burkholderia, Staphylococcus, Ralstonia and Cronotacter. The isolates produced catalase and ammonia. The amount of ammonia ranged from 60.74 ± 0.14 to 466.72 ± 0.18 mg/L. Out of the 19 siderophore producers, 17 (89.47%) were able to solubilise phosphate with solubilisation index (PSI) ranging from 1.12 ± 0.07 to 2.14 ± 0.15. The qualitative assays identified 12 isolates (63.15%) positive for IAA production with a tryptophan concentration of 5 mM, whereas 15 (78.94%) and 17 (89.47%) isolates were positive for gelatin and starch hydrolysis, respectively. Especially, 7 isolates were found to be positive for all tested assays in vitro including Pseudomonas rhodesiae (NC2), Enterobacter asburiae (NC50), Pantoea ananatis (NC63), Bacillus cereus (NC64), Burkholderia cenocepacia (NC110), Staphylococcus sciuri (NC112) and Ralstonia pickettii (NC122).@*Conclusion, significance and impact of study@#This study serves as crucial findings of multi-trait plant growth-promoting endophytic bacteria isolated from upland rice root in north-western Vietnam. The seven potential isolates positive for all tested assays could be effective PGP bacteria for bio-inoculants.

Identification and characterization of plant growth-promoting properties of bacterial endophytes from selected Zingiberaceae plants

Aims@#This study aims to isolate, characterize and screen the plant growth-promoting bacteria from Zingiberaceae plants. Plant promoting activities such as indole-3-acetic acid (IAA), phosphate solubilization, zinc solubilization and nitrogen-fixing capabilities are determined, and the IAA production of selected isolates are optimized. @*Methodology and results@#Endophytic bacteria were isolated from the plant samples by surface sterilization on nutrient agar (NA) plates and incubated at 30 °C for 2-3 days. The bacteria were identified based on their phenotypic characteristics and 16S rRNA gene sequence analyses. All isolates were identified as genera Bacillus, Lysinibacillus, Kerstersia, Klebsiella and Brucella. The isolates exhibited phosphate solubilization (1.5 ± 0.75-37.5 ± 8.75 Solubilization Index, SI), zinc solubilization (2.5 ± 0-60 ± 1.5 SI) and IAA production (0.1 ± 0.2-115.7 ± 1.6 µg/mL), while 3 isolates possessed nitrogen-fixing capabilities. Five isolates (PHAS-2, PWS-2, PWR-2, PHBS-2 and SCG-2) were selected for IAA optimization. Isolate PWR-2 produced the maximum IAA at 447.7 ± 0 µg/mL when tryptophan concentration was maintained at 1.0%.@*Conclusion, significance and impact of study@#Genera of bacteria included Bacillus, Lysinibacillus, Kerstersia, Klebsiella and Brucella were successfully isolated from Zingiberaceae plants. All the isolates showed the capability to produce IAA, while some isolates exhibited phosphate solubilization and zinc solubilization, and a few possessed nitrogen-fixing capabilities. The potential IAA production isolates could be applied for the enhancement of agricultural production that will be becoming a more widely accepted practice.

Two novel antimicrobial and anticancer peptides prediction from Vibrio sp. strain ES25

Proteins from microbes are a large source of potential raw material for novel pharmaceuticals. Endophytic bacteriaassociated with algae associated have been shown to be particularly promising candidates. In a previous study, a crudeprotein extract was isolated from an endophytic Vibrio sp. strain ES25. The extract was found to have anti-microbialactivity. Despite these promising results, further work was needed to characterize both the protein and the bacteria thatproduce it. In this study, we sought to increase the activity of the previously discovered protein through pepsin digestionas well as provide sequence data to characterize the bacterial isolate. Here, we show promising evidence that thehydrolysate produced (QA1d) was found to have a promising antimicrobial as well as anticancer properties. Through theDNA sequencing, we also provide better taxonomic information on the isolate. Finally using Liquid ChromatographyMass Spectroscopy/Mass Spectroscopy (LC-MS/MS) and in silico prediction, we identify to novel peptides producedfrom the bacterial protein that were predicted to have multifunctional activity. These results shown here indicate thesepeptides are promising candidates for anticancer drug development or antibacterial agents for the food industry.

Isolation, Identification and Antibacterial Activity of Endophytic Bacteria from Leaves of Acacia catechu

Drug resistance in bacteria is becoming an alarming problem in recent years. Post-antibiotic era is not so far. The need for novel antibiotics, chemotherapeutic agents and agrochemicals are utmost. Endophytes are microorganisms that reside in the tissues of living plants which are relatively unstudied and are potential sources of novel natural products for exploitation in medicine, agriculture and industry. The endophytes of medicinal plants participate in biochemical pathways and produce novel bioactive compounds. The aim of the study was to isolate, identify and to assess antibacterial activity of endophytic bacteria from leaves of Acacia catechu. 18 endophytic bacteria had been isolated and identified by sequencing 16S rRNA gene. The isolated endophytic bacteria were identified as Bacillus humi. Considerable in vitro antibacterial activities against a panel of human pathogenic microorganisms (Staphylococcus aureus, Streptococcus pyogenes, Bacillus cereus, Klebsiella pneumoniae, Salmonella Typhimurium and Escherichia coli) were recorded. Among 18 isolates, 15 isolates had shown inhibitory activity against Staphylococcus aureus and Salmonella Typhimurium and 10 isolates had shown inhibitory activity against Klebsiella pneumoniae

Research Progress of Endophytic Bacterial Resources and Their Secondary Metabolites / 中国实验方剂学杂志

Endophytic bacteria exist in the host and do not cause obvious damage to the host，which is an important part of the host ecosystem. Endophytic bacteria are a kind of important microbial resources with diverse species and wide distribution. In the process of long-term coevolution between endophytic bacteria and host，many symbiotic relationships，such as antagonism and reciprocity，have been gradually formed，which can directly or indirectly regulate the growth and development of host，assist host to resist diseases and insect pests，environmental stress and other biological processes. Endophytic bacteria can produce a variety of secondary metabolites in the process of symbiosis with the host，which plays an important role in the development of new natural products. In recent years，endophytic bacteria and their secondary metabolites have been widely used in the research and development of new drugs，biological control and other fields. In this paper，the diversity，species identification and secondary metabolites of endophytic bacterial resources are reviewed，and the future development direction is discussed，hoping to provide reference for the further development and utilization of endophytic bacterial resources.

Evaluation of the biocontrol potential of endophytic bacteria isolated from Coffea liberica (w. Bull ex hiern) against brown eyespot-causing fungal phytopathogen

Aims@#The study aims to investigate the potential of the endophytic bacteria as an alternative to control the devastating brown eyespot disease caused by Cercospora sp. in coffee plants. The fungal phytopathogen causes severe leaf fall and berry damages resulting in serious yield losses in coffee farms in the Philippines and worldwide. Currently, the management of this fungal infection relies heavily on synthetic fungicides, which may be of major environmental concern. @*Methodology and results@#Endophytic bacteria were isolated from the intercellular tissues of Coffea liberica leaves by surface sterilization, maceration, dilution technique, plating on trypticase soy agar and colony characterization. Fourteen isolated endophytic bacteria were screened for their ability to inhibit the mycelial growth of Cercospora sp. through modified dual culture assay. Isolates HCC10-3SC3, HCC10-3SC2, HCC10-1SC1, ICC10-3SC1, and ICC10-1SC1 yielded the highest percent inhibition of radial growth (PIRG) with 59.56%, 60.92%, 60.96%, 64.36%, and 67.06% respectively and are statistically significant (p<0.05) compared to the antibiotic control nystatin. The top five performing endophytic bacteria were subjected to hydrolytic enzyme production assays and found to exhibit amylolytic, lipolytic, proteolytic, chitinolytic, and cellulolytic activities. Based on the morphological and molecular identification by the 16S rRNA sequence analysis, isolates showed the similarity with Staphylococcus cohnii, Bacillus siamensis, Staphylococcus hominis, and Kosakonia cowanii found in GENBANK. @*Conclusion, significance and impact of study@#The study revealed the biological control potential of endophytic bacteria agents against the brown eyespot-causing fungus in coffee.

Endophytic Enterobacter cloacae exhibits antagonistic activity against Pythium damping-off of cucumber / Enterobacter cloacae endofítica exibe atividade antagonista contra a podridão de pepino causada por Pythium

ABSTRACT: The study was performed to examine the potential presence of biological control agents against Pythium damping-off disease of cucumber.Examining eleven bacterial strains isolated from acid lime roots and rhizosphere soil showed that the bacterial strain RB1 was the most efficient in suppressing mycelial growth of P. aphanidermatum, producing an inhibition zone of 5mm. Scanning electron microscopy study of the mycelia at the interaction zone showed that the pathogen hyphae were deformed and shriveled by the bacterial strain.In pot experiments, pretreatment with the RB1 bacterial strain reduced disease incidence significantly by 63%.The bacterial strain did not exhibit any negative significant effects on cucumber growth (plant height and root dry weight) in comparison with untreated control under growth chamber conditions. Molecular identification of strain RB1 based on the 16S rRNA gene revealed that it is Enterobacter cloacae. Findings from this study suggested that E. cloacae has a potential to be used as a biocontrol agent for suppressingcucumber damping-off disease caused by P. aphanidermatum. This is the first report of the antagonistic activity of E. cloacae against P. aphanidermatum-induced damping-off of cucumber.

RESUMO: O estudo foi realizado para examinar a presença potencial de agentes no controle biológico da doença do apodrecimento do pepino causado por Pythium. Examinando onze cepas bacterianas isoladas de raízes de cal ácida e solo da rizosfera mostraram que a cepa bacteriana RB1 foi a mais eficiente na supressão do crescimento micelial de P. aphanidermatum, produzindo uma zona de inibição de 5 mm. O estudo de microscopia eletrônica de varredura dos micélios na zona de interação mostrou que as hifas do patógeno foram deformadas e enrugadas pela cepa bacteriana. Em experimentos com vasos, o pré-tratamento com a cepa bacteriana RB1 reduziu significativamente a incidência da doença em 63%. A cepa bacteriana não exibiu nenhum efeito negativo. Efeitos significativos no crescimento do pepino (altura da planta e peso seco da raiz), em comparação com o controle não tratado sob condições da câmara de crescimento. A identificação molecular da cepa RB1 com base no gene 16S rRNA revelou que é a Enterobacter cloacae. Os resultados deste estudo sugerem que E. cloacae tem potencial para ser usado como agente de biocontrole para suprimir a doença da podridão de pepino causada por P. aphanidermatum. Este é o primeiro relato da atividade antagônica de E. cloacae contra o amortecimento induzido por P. aphanidermatum de pepino.

Bioconversion of sugarcane molasses to poly(3-hydroxybutyrate-co-3- hydroxyvalerate) by endophytic Bacillus cereus RCL 02

Sugarcane molasses, the by-product of sugar industry are rich in nutrients, growth factors and minerals and areefficiently utilized by the microorganisms for growth and production of primary as well as secondary metabolitesof commercial importance. In this communication, we report the utilization of sugarcane molasses as the solesource of carbon for the production of copolymers of polyhydroxyalkanoates (PHAs) with improved materialproperties. The endophytic bacterium Bacillus cereus RCL 02 (MCC 3436) produced 7.8 g/L of PHA whengrown in MS medium with 4% (w/v) sugarcane molasses under batch cultivation. Proton nuclear magneticresonance (1H NMR) analysis revealed that the copolymer so produced contain 12.4 mol% 3-hydroxyvalerate(3HV) along with 87.6 mol% 3-hydroxybutyrate (3HB). The copolyester, P(3HB-co-12.4 mol%-3HV)has been isolated and purified following standard solvent extraction method and partially characterized byFourier-transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric (TG) and differential scanningcalorimetric (DSC) analysis. The material and thermal properties of the copolyester so produced indicated itspotential for industrial application.

Biosurfactant from endophytic Bacillus cereus: Optimization, characterization and cytotoxicity study

Aims@#The increased importance of biosurfactant in the recent past is mainly due to their applications in various industries ranging from petroleum to pharmaceuticals. Their biodegradability and environmental compatibility with low toxicity makes it even more interesting. Microbial production of biosurfactant is found to be a viable option as they are diverse, eco-friendly, facilitate large scale production, able to perform under extreme conditions etc. One class of microbes that is endophytes are known to show great potential in producing different varieties of medically and industrially significant biological compounds. The present study focuses on the screening and production of biosurfactant from endophytic bacteria. @*Methodology and results@#Of all the isolates tested, one endophyte identified as Bacillus cereus HM998898 was found to produce maximum biosurfactant. Statistical method Plackett burman was used to optimize the media for the maximum production and the ideal composition was found to be KNO3 (1 g/L), Gingley oil (2 mL), K2HPO4 (2.5 g/L), KH2PO4 (0.75 g/L), MgSO4·5H2O (0.5 g/L), FeSO4.7H2O (0.005 g/L) and NaCl (0.025 g/L). The extracted biosurfactant was characterized and was identified to be glycolipid. This was further tested for biocompatibility against Fibroblast (3T3) cells and was evaluated for their anti tumor activity against Hep2 cells. @*Conclusion, significance and impact of study@#The biosurfactant produced was found to induce toxicity to cancer cells at appreciable levels while they remained non-toxic to normal cells supporting the possible applications of biosurfactant in medical field.

Diversity of Endophytic and Epiphytic Bacteria From Sugarcane in Khuzestan, Iran

Abstract Diverse microorganisms are living as endophytes in plant tissues and as epiphytes on plant surfaces in nature. Commercial formulations of bacteria antagonist to plant pathogenic microbes and ice nucleation active bacteria have been utilized as an environmentally safe method to manage plant disease and to prevent frost damage respectively. Bacteria were isolated from the leaf and sheath of sugarcane (CP69-1026 CP57-614, CP48-103, CP73-21, and CP70-1143 cultivars) verities grown in the field in Khuzestan province, Iran. Bacteria were found in both sheaths and leaves of sugarcane plants which they were significantly higher in density in leaves and which most were endophytic. The bacterial strains were 10 groups on the basis of the biochemical characteristic, which their 16S rRNA encoding gene from representatives were amplified and subjected to sequencing. Results of sequences analyze using blast software from the NCBI website and phylogenetic analysis showed that the representative strains belonged to a wide variety of phylogenetic groups. These results indicated that they were closely related to Burkholderia and Ralstonia from β-Proteobacteria, Mesorhizobium, Ochrobactrum, Sphingomonas from α-Proteobacteria, Microbacterium, Curtobacterium and Leifsonia from Actinobacteria and Xanthomonas from γ-Proteobacteria. This is the first report of the presence of endophytic and epiphytic bacteria from sugarcane in Khuzestan, Iran.

Isolation and Characterisation of Endophytic Strain Paenibacillus polymyxa SR19 from Urtica dioica and the Study of Their Effect against Fusarium oxysporum f. sp Tomato

In an attempt to obtain biological control agents for fusariose wilt, a total of 54 endophytic bacterial strains were isolated from the root of plants Urtica dioica and screened for in vitro antagonist activity against Fusarium oxysporum. Among the 54 bacterial isolates, 27 isolates exhibited more than 60% inhibition of mycelia growth of Fusarium oxysporum. The strain R19 which exhibited the most obvious antagonistic activity was selected for greenhouse studies. The SR19 had no pathogenicity and was identified as Paenibacillus polymyxa based on its phenotypical and biochemical properties as well as its 16S rRNA gene sequence. Growth chamber studies resulted in statistically significant increases in inoculating tomato seedling with the endophytic strain SR19 which in turn resulted in improving plant seedling stand by 32% and increasing fresh weights of root and fresh weight of aerial biomass of plants over the untreated pathogen control by 6.95 g and 7.96 g, respectively. Strain SR19 is a potential biological control agent that may contribute to the protection of tomato plants against fusariose wilt.

Isolation and Biochemical Characterisation of Endophytic Bacillus spp from Urtica dioica and Study of Their Antagonistic Effect against Phytopathogens

Endophytic bacteria have been isolated from the roots of Urtica dioica. A total of 54 endophytic bacteria were isolated from the underground parts using suitable surface sterilisation protocol. Three isolates R45a; R45b; R21a were tested for antagonism effect against Fusarium oxysporum, Colletotrichum gloeosporioides, Rhizoctonia solani, Phytophthora parasitica in dual culture method. Significant inhibitory effects on mecylial radial growth have been revealed with a percentage superior or equal to 75%. These strains were Gram-positive rods. Cultures on nutrient agar showed irregular, entirely cream coloured colonies that are strictly aerobic and capable of forming endospore. They belong probably to the genus of Bacillus spp.

Mangrove endophyte promotes reforestation tree (Acacia polyphylla) growth

ABSTRACT Mangroves are ecosystems located in the transition zone between land and sea that serve as a potential source of biotechnological resources. Brazil's extensive coast contains one of the largest mangrove forests in the world (encompassing an area of 25,000 km2 along all the coast). Endophytic bacteria were isolated from the following three plant species: Rhizophora mangle, Laguncularia racemosa and Avicennia nitida. A large number of these isolates, 115 in total, were evaluated for their ability to fix nitrogen and solubilize phosphorous. Bacteria that tested positive for both of these tests were examined further to determine their level of indole acetic acid production. Two strains with high indole acetic acid production were selected for use as inoculants for reforestation trees, and then the growth of the plants was evaluated under field conditions. The bacterium Pseudomonas fluorescens (strain MCR1.10) had a low phosphorus solubilization index, while this index was higher in the other strain used, Enterobacter sp. (strain MCR1.48). We used the reforestation tree Acacia polyphylla. The results indicate that inoculation with the MCR1.48 endophyte increases Acacia polyphylla shoot dry mass, demonstrating that this strain effectively promotes the plant's growth and fitness, which can be used in the seedling production of this tree. Therefore, we successfully screened the biotechnological potential of endophyte isolates from mangrove, with a focus on plant growth promotion, and selected a strain able to provide limited nutrients and hormones for in plant growth.

Diversity of endophytic bacteria in Astragali Radix analyzed by Illumina MiSeq high-throughput sequencing technology / 中草药

Objective This study aimed to analyze the diversity of endophytic bacterial communities, and to provide reference to the oriented processing technology, which helps to screen bacteria fermentation and conversion in the active ingredients of Astragali Radix. Methods The 16S rDNA V3-V4 region of Astragali Radix was sequenced by Illumina MiSeq high-throughput sequencing technology, and the abundance of species and other biological information were analyzed. Results The results showed that the numbers of effective sequences and OTUs for sample were 40 051 and 967, respectively. The number of sequencing was close to saturation, and the sequencing data volume was reasonable. The endophytic bacteria of Astragali Radix mainly belonged to Anderseniella, Bacillus, Burkholderia, Acinetobacter, Stenotrophomonas, and Oceanobacillus. Conclusion The diversity of endophytic bacteria was low in Astragali Radix. The dominant population of endophytic bacteria in Astragali Radix belongs to Anderseniella and Bacillus.

Illumina-based analysis of endophytic bacterial diversity of tree peony (Paeonia Sect. Moutan) roots and leaves

ABSTRACT Diverse communities of bacteria inhabit plant tissues and those bacteria play a crucial role for plant health and growth. Tree peony (Paeonia Sect. Moutan) is known for its excellent ornamental and medicinal values as Chinese traditional plant, but little is known about its associated bacterial community under natural conditions. To examine how endophytic bacteria in tree peony vary across tissues and cultivars, PCR-based Illumina was applied to reveal the diversity of endophytic bacteria in tree peony. A total of 149,842 sequences and 21,463 operational taxonomic units (OTUs) were obtained. The OTU abundance of roots was higher than leaves across other three cultivars except for 'Kinkaku' and 'Luoyanghong'. The community was composed of five dominant groups (Proteobacteria, Firmicutes, Bacteroidetes, Acidobacteria and Actinobacteria) in all samples. Endophytic bacteria community structures had changed in leaves and roots. Sequences of Pseudomonas and Enterobacteriaceae were prevalent in root samples, whereas Succinivibrio and Acinetobacter were the dominant genus in leaf samples. Otherwise, the distribution of each dominant genus among the 5 cultivars was either varied. These findings suggested that both plant genotype and tissues contribute to the shaping of the bacterial communities associated with tree peony.

Anticandidal effect of endophytic bacteria isolated from Equisetum arvense L. against Candida albicans and Candida glabrata

ABSTRACT Equisetum arvense, a fern species possesses a number of pharmaceutical prospective. In the present study, a total of 103 endophytic bacteria isolated from E. arvense and were evaluated for their anticandidal property against five Candida species, two C. albicans, C. glabrata, C. saitoana and C. geochares. Out of them fifty one were identified as per the morphological and molecular characterisation using 16S rRNA gene sequencing and among them, ten promising endophytic bacteria were mentioned in the present study. Among ten endophytic bacteria, Psychrobacillus insolitus and Curtobacterium oceanosedimentum exerted highest anticandidal effect against C. albicans KACC 30062 and C. glabrata KBNO6P00368, with diameter of inhibition zones of 21.30±0.41 and 18.24±0.12 mm, respectively. When the endophytic bacteria cultures were successively fractionated using different solvents, only the butanol fraction of Psychrobacillus insolitus and Curtobacterium oceanosedimentum had anticandidal activity, with inhibition zones of 20.12±0.28 mm and 12.33±0.11 mm, respectively. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of the butanol fractions ranged from 250 to 500 and 500 to 1,000 µg/mL, respectively. Scanning electron microscope (SEM) analysis showed impaired membrane of C. albicans and C. glabrata at the MIC, indicating that butanol extract lysed the cell membrane and caused cell death. The endophytic bacteria derived from E. arvense can be a valuable resource for the development of natural anticandidal agents to manage candidiasis.

Cultivable bacterial diversity of Paris polyphylla var. chinensis with 16 S rRNA sequence analysis / 中草药

Objective To analyze the bacterial diversity in stem rot and healthy plants of Paris polyphylla var. chinensis. Methods Bacterial strains were isolated from rhizomes, stems and leaves of the diseased and healthy plants of P. polyphylla var. chinensis using beef extract-peptone medium. Using 16 S rRNA universal primers 27F/1492R for PCR amplification, combined with DNA sequencing technology to preliminary identification the bacterial strains. Results The bacteria could be divided into 23 microbial species, belonging to 11 genera, isolated from healthy and diseased plants of P. polyphylla var. chinensis. Eleven endophytic bacteria, belonging to 4 genera were contained from healthy plants, in which there were 9, 10, and 5 species isolated from rhizomes, stems and leaves, respectively. Fourteen endophytic bacteria, belonging to 10 genera were contained from diseased plant, in which there were 11, 8, and 3 species isolated from rhizomes, stems, and leaves, respectively. The content of endophytic bacteria in rhizome of healthy plant was the highest, reached up to 2.999 × 105 cfu/g, while that in leaf was the lowest with 7.32 × 104 cfu/g. The quantities of Bacillus species in rhizome (73.3%), stem (67.1%), and leaf (81.8%) of healthy plant were the highest groups, Pseudomonas species in rhizome (35.6%), stem (50.3%) and leaf (60.5%) of diseased plants were the highest groups. Shannon-Wiener index and evenness index of healthy plant of P. polyphylla var. chinensis were higher than that of diseased plants. Conclusion The dominant group in the healthy plant of P. polyphylla var. chinensis was Bacillus, while the dominant groups in the diseased plant of P. polyphylla var. chinensis was Pseudomonas. The population diversity of the cultivable bacteria in healthy plant of P. polyphylla var. chinensis was more abundant than that of diseased plant.