Effect Of Endophytic Bacteria Research Articles

Effect of endophytic bacteria <i>Bacillus subtilis</i>on metabolic processes in potato tubers during storage

The article examines the effect produced by the preplant inoculation of potato tubers with Bacillus subtilis on biochemical processes occurring in the tubers of a new crop during the postharvest period at different storage periods. The content of malondialdehyde in tubers treated with strains 10-4 and 26D decreased by 15.5 and 35.5% and by 14.9 and 13.6% relative to the control after one and six months, respectively. The proline content in tubers pretreated with strain 10-4 differed insignificantly from the control in both storage periods, while in the case of strain 26D, it was lower than the control by 14.7 and 26.3%. First, the activity of protective proteins in treated tubers decreased relative to the control; then, the activity of trypsin inhibitors in tubers was found to significantly exceed that in tubers stored for a short time. The protein content of pretreated tubers was initially higher than that of the control; then, it was either at the same level (strain 26D) or 15% lower than the control (strain 10-4). The content of ascorbic acid in tubers pretreated with strain 10-4 exceeded that of the control by 16.1 and 17.9% after one and six months of storage, respectively, whereas in the case of strain 26D, no difference from the control was noted. The amount of reducing sugars was 39.4% lower than the control after one and six months of storage (strain 10-4) and 35.6% after six months of storage (strain 26D). The pretreatment with strains 10-4 and 26D positively affected the main biochemical parameters of tubers during long-term storage, providing a protective effect and preserving the biological value of produce.

Effect of endophytic bacteria from Algerian prickly pear roots on wheat under drought stress

Cactus are among the most drought tolerant plants. As Opuntia is able to grow under the stress of drought, this study aims to check if endophytic bacteria isolated from cactus roots have beneficial potential for crops such as wheat during drought. Two endophytic bacterial isolates were isolated from the roots of the cactus and screened for their plant growth promoting characteristics, such as N-free growth and auxin production. These bacteria have demonstrated their potential to promote the growth of durum wheat under in-vitro conditions and have been identified as Pseudomonas putida and P.brassicacearum, following the sequencing of the 16S rRNA gene and phylogenetic analysis, and significantly improved growth parameters such as seeding length compared to the unobstructed control. After 05 days of contact of the two bacteria, P.putida and P.brassicacearum, with sprouted wheat seeds, a root growth rate of (39.88% and 62.14%, respectively) was recorded. The same effect on the growth of wheat roots is caused by the volatile substances of these bacteria deposited separately, with a rate of (53.30% and 24.18%) respectively. Symptoms of drought stress were visibly reduced on seedlings inoculated with P.putida and P.brassicacearum bacteria, a result supported by a growth rate of root parameters in length (260.83% and 179.60%), surface (21.98% and 60.17%) and scope (59.46% and 62.67%), respectively. This work opens up many perspectives for the characterization and selection of endophyte bacteria of under-used drought-tolerant species such as cacti for the improvement of the growth of field crops. These results promote the deployment of Pseudomonas sp as an effective biofertilizer in wheat.

Can Bacterial Endophytes Be Used as a Promising Bio-Inoculant for the Mitigation of Salinity Stress in Crop Plants?-A Global Meta-Analysis of the Last Decade (2011-2020).

Soil salinity is a major problem affecting crop production worldwide. Lately, there have been great research efforts in increasing the salt tolerance of plants through the inoculation of plant growth-promoting endophytic bacteria. However, their ability to promote plant growth under no-stress and salinity-stress conditions remains largely uncertain. Here, we carried out a global meta-analysis to quantify the plant growth-promoting effects (improvement of morphological attributes, photosynthetic capacity, antioxidative ability, and ion homeostasis) of endophytic bacteria in plants under no-stress and salinity-stress conditions. In addition, we elucidated the underlying mechanisms of growth promotion in salt-sensitive (SS) and salt-tolerant (ST) plants derived from the interaction with endophytic bacteria under no-stress and salinity-stress conditions. Specifically, this work encompassed 42 peer-reviewed articles, a total of 77 experiments, and 24 different bacterial genera. On average, endophytic bacterial inoculation increased morphological parameters. Moreover, the effect of endophytic bacteria on the total dry biomass, number of leaves, root length, shoot length, and germination rate was generally greater under salinity-stress conditions than no-stress conditions. On a physiological level, the relative better performance of the bacterial inoculants under the salinity-stress condition was associated with the increase in total chlorophyll and chlorophyll-b, as well as with the decrease of 1-aminocylopropane-1-carboxylate concentration. Moreover, under the salinity-stress condition, bacterial inoculation conferred a significantly higher increase in root K+ concentration and decrease in leaf Na+ concentration than under the no-stress condition. In SS plants, bacterial inoculation induced a higher increase in chlorophyll-b and superoxide dismutase activity, as well as a higher decrease in abscisic acid content, than in ST plants. Under salinity-stress, endophytic bacterial inoculation increased root K+ concentration in both SS and ST plants but decreased root Na+ concentration only in ST plants. Overall, this meta-analysis suggests that endophytic bacterial inoculation is beneficial under both no salinity-stress and salinity-stress conditions, but the magnitude of benefit is definitely higher under salinity-stress conditions and varies with the salt tolerance level of plants.

Characterization of Arsenic-Resistant Endophytic Bacteria From Alfalfa and Chickpea Plants.

The present investigation was carried out to isolate arsenic (As)-resistant endophytic bacteria from the roots of alfalfa and chickpea plants grown in arsenic-contamination soil, characterize their As tolerance ability, plant growth-promoting characteristics, and their role to induce As resistance by the plant. A total of four root endophytic bacteria were isolated from plants grown in As-contaminated soil (160–260-mg As kg−1 of soil). These isolates were studied for plant growth-promoting (PGP) characteristics through siderophore, phosphate solubilization, nitrogen fixation, protease, and lipase production, and the presence of the arsenate reductase (arsC) gene. Based on 16S rDNA sequence analysis, these isolates belong to the genera Acinetobacter, Pseudomonas, and Rahnella. All isolates were found As tolerant, of which one isolate, Pseudomonas sp. QNC1, showed the highest tolerance up to 350-mM concentration in the LB medium. All isolates exhibited phosphate solubilization activity. Siderophore production activity was shown by only Pseudomonas sp. QNC1, while nitrogen fixation activity was shown by only Rahnella sp. QNC2 isolate. Acinetobacter sp. QNA1, QNA2, and Rahnella sp. QNC2 exhibited lipase production, while only Pseudomonas sp. QNC1 was able to produce protease. The presence of the arsC gene was detected in all isolates. The effect of endophytic bacteria on biomass production of alfalfa and chickpea in five levels of arsenic concentrations (0-, 10-, 50-, 75-, and 100-mg kg−1 soil) was evaluated. The fresh and dry weights of roots of alfalfa and chickpea plants were decreased as the arsenic concentration of the soil was increased. Results indicate that the fresh and dry root weights of alfalfa and chickpea plants were significantly higher in endophytic bacteria-treated plants compared with non-treated plants. Inoculation of chickpea plants with Pseudomonas sp. QNC1 and Rahnella sp. QNC2 induced lower NPR3 gene expression in chickpea roots grown in soil with the final concentration of 100-mg kg−1 sodium arsenate compared with the non-endophyte-treated control. The same results were obtained in Acinetobacter sp. QNA2-treated alfalfa plants grown in the soil plus 50-mg kg−1 sodium arsenate. These results demonstrated that arsenic-resistant endophytic bacteria are potential candidates to enhance plant-growth promotion in As contamination soils. Characterization of bacterial endophytes with plant growth potential can help us apply them to improve plant yield under stress conditions.

ACC deaminase containing endophytic bacteria ameliorate salt stress in Pisum sativum through reduced oxidative damage and induction of antioxidative defense systems.

Approximately 6% of the world's total land area and 20% of the irrigated land are affected by salt stress. Egypt is one such country affected by salt-stress problems. This paper focuses on the role of isolated bacteria, such as Bacillus subtilis and Pseudomonas fluorescens, in alleviating the harmful effects of salt stress. The results show that the irrigation of plants with different concentrations of saline water (0, 75, and 150 mM NaCl) leads to significantly decreased growth criteria, photosynthetic pigments (i.e., chl a, chl b, and carotenoids), and membrane stability index (MSI) values. Moreover, malondialdehyde (MDA), glutathione content, endogenous proline, the antioxidant defense system, 1-aminocyclopropane-1-carboxylic acid (ACC) content, ACC synthase (ACS), ACC oxidase (ACO), and Na+ content were significantly increased under NaCl-stress exposure. On the contrary, treatment with endophytic bacteria significantly increased the resistance of pea plants to salt stress by increasing the enzymatic antioxidant defenses (i.e., superoxide dismutase, catalase, peroxidase, and glutathione reductase), non-enzymatic antioxidant defenses (i.e., glutathione), osmolyte substances such as proline, and antioxidant enzyme gene expression. As a result, endophytic bacteria's use was significantly higher compared to control values for indole-3-acetic acid (IAA), gibberellic acid GA3, MSI, and photosynthetic pigments. The use of endophytic bacteria significantly decreased Na+ accumulation while, at the same time, promoting K+ uptake. In conclusion, the induction of endophytic bacterium-induced salt tolerance in pea plants depends primarily on the effect of endophytic bacteria on osmoregulation, the antioxidant capacity, and ion uptake adjustment by limiting the uptake of Na+ and, alternatively, increasing the accumulation of K+ in plant tissue.

Culturable bacterial endophytes isolated from citrus leaves enhance seedling growth of Solanum melongena L.

Endophytes have a symbiotic relationship with plants and play an important role in supporting the plant growth. The objective of this study was to examine the effect of endophytic bacteria isolated from citrus leaves on promoting seedling growth and influencing some biochemical attributes in brinjal (Solanum melongena L.). Isolated bacteria were characterized based on molecular tool 16S rRNA. The bacterial isolates were identified as Enterococcus faecalis, Brevibacillus borstelensis, Staphylococcus haemolyticus, Bacillus safensis, B. megaterium, B. cereus, Pseudomonas sp., P. aeruginosa, Enterobacter hermachei and Proteus mirabilis based on 16S rRNA sequence homology and phylogenetic analysis. The leaves of brinjal seedlings were inoculated with these bacterial endophytes by injection method under greenhouse conditions. About one month after inoculation, the plants were analysed for their physical (shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight,), bio-physical (chlorophyll a and b contents, and relative leaf water content), and biochemical (total phenolic, flavonoids and carotenoids contents) parameters. In the present study, Bacillus safensis and Pseudomonas sp. significantly increased the shoot length, shoot fresh and dry weights, relative leaf water content, leaf chlorophyll b content, phenolics and flavonoids in brinjal plants after the application of the bacterial inoculum. However, carotenoids content remained unaffected by the bacterial inoculum. Thus, some bacterial endophytes possess prospective potential in improving plant growth and could be used as inoculants to establish a sustainable crop production system.

Endophytic bacteria enhanced growth, fruit yield and quality in Phalsa (Grewia asiatica L.)

There is an immense need to replace chemical fertilizers with biofertilizers to address the soil, environment, and health issues. Endophytic bacteria act as biocontrol agents and promote plant growth and yield. Present study was designed to evaluate the microbial effect of endophytic bacteria on growth, fruit yield and quality of phalsa (Grewia asiatica L.). Three years old healthy, disease and insect-pest free plants were selected for the study. Experiment was laid out in randomized complete block design with four treatments; control, two bacteria such as Burkholderia phytofirmans strain PsJN, Bacillus sp. strain MN54 and their combination (PsJN + MN54) with three replications. The treatments were applied after pruning (January) and flowering (March) as plants need nutrition for both vegetative and reproductive growth. Combined application of PsJN + MN54 resulted in greater vegetative and reproductive growths of plants i.e. number of shoots/plant (29.6), number of leaves/shoot (15.9), number of fruit clusters/shoot (14.0), number of fruits/cluster (14.1), fruit weight (13.7 g) and yield/plant (8.8 kg) than PsJN or MN54 alone and control. Fruit biochemical characteristic i.e. TSS (8.78 °Brix), TA (0.53%), ascorbic acid (44.44 mg 100 mL-1), total sugar (12.29%), reducing sugar (9.59%) and non-reducing sugar (4.92%) contents were also higher in plants treated with PsJN + MN54. All growth, yield and biochemical parameters correlated positively with each other except titratable acidity. Based on performance, the combined treatment (PsJN + MN54) can be applied at two stages, after pruning and at flowering, for better growth, yield and quality of phalsa crop.

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Defense Responses and Changes in Symbiotic Gut Microflora in the Colorado Potato Beetle Leptinotarsa decemlineata under the Effect of Endophytic Bacteria from the Genus Bacillus

Phytophagous insects and host plants have a complex of microsymbionts and make up a united co-evolving system with them. Microsymbiotic complexes are actively involved in stress responses of macrosymbionts. We established that a treatment of potato plants with endophytic bacterial strains Bacillus thuringiensis var. thuringiensis-5689, B. th. var. kurstaki-5351, and Bacillus subtilis 26D decreased the survival rate of the plant feeder, Colorado potato beetle Leptinotarsa decemlineata Say. The B. th. strains suppressed phenoloxidase and acetylcholinesterase activities in the beetle hemolymph. An antagonistic relationship was found between endophytic bacteria B. subtilis 26D and beetle symbiotic bacteria from the genera Acinetobacter and Enterobacter, with the former being able to suppress the growth of endophytic colonies. The recombinant B. subtilis strain 26D Cry, containing the B. th. var. kurstaki δ-endotoxin cry1Ia gene, combined the ability of the original B. subtilis 26D strain to suppress the development of beetle symbionts and immune responses with a production of the Cry toxin, thus leading to a high mortality of the phytophage.

Effects of Endophytic Bacteria on Disease and Growth in Plants under Biotic Stress

The aim of this study was to reveal the effects of four endophytic bacteria (EB) (Ochrobactrumsp. CB36/1, Pantoea agglomerans CC37/2, Bacillus thuringiensis CA41/1 and Pseudomonas fluorescens CC44) on the plant development of tomato and pepper and the effects against bacterial spot disease caused by Xanthomonas euvesicatoria (Xe) in both hosts. EB applied on tomato and pepper seedlings cultivated in a sterile peat growing medium in a climate chamber in two different periods to the roots. The pathogen inoculated on the leaves by spraying. Disease severity was measured by different scales for tomatoes and peppers, and plant development parameters were determined at the end of the study. The antagonistic effects of EB against Xe and 1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase activities were determined with in vitro studies. The effect of endophytic bacteria on tomato and pepper varied according to the host plant x endophyte x pathogen combination. While no bacteria were effective against the pathogen in vitro, Ochrobactrum sp. CB36/1 inhibited the disease severity by 37% in tomato plants, but this effect was not observed in pepper. Tomato and especially pepper plants under disease stress had root and shoot fresh and dry weight increased by 28% to 128% by EB. The measurable effects of EB under biotic stress were determined to be higher than in stress-free conditions. In conclusion, the endophytic bacteria used in the study have potential for use within sustainable integrated agricultural concept framework, with their effects determined to vary according to the host, pathogen and endophytic bacteria.

Community structure and difference of endophtic bacteria in Aquilaria sinensis with and without agarwood

Aquilaria sinensis can generate agarwood, which is closely related with endophyte. Up to now, studies mainly focused on the effects of endophytic fungi on agarwood formation, but studies about endophytic bacteria are rarely reported. In our research, the T-RFs and Shannon index of endophytic bacteria in samples of agarwood increase. The number of distinctive T-RFs fragments of corresponding samples in the same group accounted for more than 60% the number of total T-RFs fragments. In samples of no-agarwood, the dominant bacterial population are Anoxybacillus, Clostridium, Candidatus endobugula, Lysinibacillus. In samples of agarwood, the dominant bacterial population are Clostridium, Lysinibacillus, Luteimonas, phytoplasma. Besides, there are. specific T-RFs fragment in samples of agarwood and no-agarwood respectively. When we perform cluster analysis, we found samples of agarwood highly gather together and samples of no-agarwood highly gather together. This means community of endophytic bacteria emerge significant and regular changes during agarwood formation, which may be result of agarwood production, or maybe it is important reason of agarwood production. In this paper, we obtain more comprehensive and accurate community of endophytic bacteria in Aquilaria sinensis and it's variation during agarwood formation using T-RFLP, which is first study of effects of endophytic bacteria on agarwood formation, and will help to exploit resource of endophytic bacteria more reasonably.

Effect of Entophytic Bacteria on the Rooting and Establishment of Cuttings of Hibiscus Rosasinensis

Any plants that are propagated vegetatively are likely to have an enduring community of bacterial colonists that are transferred in successive progeny generations. The plant growth promoting effects attributed to endophytes are due to the direct production of phytohormones such as auxins, cytokinins etc or through the induction of phytohormone synthesis by the plant. Being a vegetatively propagated plant species, Hibiscus rosasinensis shoots are amenable for treatment with endophytic bacteria. The effect of endophytic bacteria on the rooting and establishment of cuttings of Hibiscus rosasinensis was studied here. Four endophytic isolates and the consortium of them screened for their plant hormone production was used for this study. The treatment of cuttings with the tomato isolate LEE19 (Klebsiella sp.) for 12 hours, showed 75 % sprouting of cuttings and the highest shoot and root parameters compared to uninoculated cuttings. The rooting also increased to 100 % in LEE19 treatment. The treatment of entophytic bacteria increased significantly the number of leaves/ cutting, the shoot length, root length and fresh weight of roots. So the pre-plant stem treatment of cuttings can be recommended as a strategy for substituting or supplementing the use of chemical plant growth hormones in vegetative propagation of cuttings.

Symbiotic interaction of endophytic bacteria with arbuscular mycorrhizal fungi and its antagonistic effect on Ganoderma boninense

Endophytic bacteria (Pseudomonas aeruginosa UPMP3 and Burkholderia cepacia UMPB3), isolated from within roots of oil palm (Elaeis guineensis Jacq.) were tested for their presymbiotic effects on two arbuscular mcorrhizal fungi, Glomus intraradices UT126 and Glomus clarum BR152B). These endophytic bacteria were also tested for antagonistic effects on Ganoderma boninense PER 71, a white wood rot fungal pathogen that causes a serious disease in oil palm. Spore germination and hyphal length of each arbuscular mycorrhizal fungal (AMF) pairing with endophytic bacteria was found to be significantly higher than spores plated in the absence of bacteria. Scanning electron microscopy (SEM) showed that the endophytic bacteria were scattered, resting or embedded on the surface hyaline layer or on the degraded walls of AMF spores, possibly feeding on the outer hyaline spore wall. The antagonistic effect of the endophytic bacteria was expressed as severe morphological abnormalities in the hyphal structures of G. boninense PER 71. The effects of the endophytic bacteria on G. boninense PER 71 hyphal structures were observed clearly under SEM. Severe inter-twisting, distortion, lysis and shriveling of the hyphal structures were observed. This study found that the effect of endophytic bacteria on G. intraradices UT126 and G. clarum BR152B resembled that of a mycorrhiza helper bacteria (MHB) association because the association significantly promoted AMF spore germination and hyphal length. However, the endophytic bacteria were extremely damaging to G. boninense PER 71.