Inter and intra-population variability of Pongamia pinnata: a bioenergy legume tree

Pongamia pinnata is an oil-producing tree species with multiple uses and considerable potential as a bioenergy crop. This investigation was carried out to assess the extent of genetic structure in a representative set of 226 individuals of Pongamia pinnata encompassing seven populations as a prelude to utilization of promising and genetically divergent material in breeding programmes. Molecular polymorphism was 67.18% with ten inter simple sequence repeats (ISSR) between the individuals indicating modest levels of genetic variation in the Pongamia pinnata germplasm collected. The within-population variation based on ISSR polymorphism was 32.34% and polymorphism at the species level was 94.3%. Genetic differentiation between populations (GST = 0.61) was positively correlated with geographical distance. The data obtained indicate an immediate need to widen the genetic base of Pongamia pinnata germplasm for proper characterization, and for extensive plantations of elite varieties to meet the demands for biodiesel.     

Pongamia pinnata: An Untapped Resource for the Biofuels Industry of the Future

Pongamia pinnata (L.) Pierre is a fast-growing leguminous tree with the potential for high oil seed production and the added benefit of the ability to grow on marginal land. These properties support the suitability of this plant for large-scale vegetable oil production required by a sustainable biodiesel industry. The future success of P. pinnata as a sustainable source of feedstock for the biofuels industry is dependent on an extensive knowledge of the genetics, physiology and propagation of this legume. In particular, research should be targeted to maximizing plant growth as it relates to oil biosynthesis. This review assesses and integrates the biological, chemical and genetic attributes of the plant, providing the basis for future research into Pongamia’s role in an emerging industry.     

In Vitro Screening of Anti-lice Activity of Pongamia pinnata Leaves

Growing patterns of pediculocidal drug resistance towards head louse laid the foundation for research in exploring novel anti-lice agents from medicinal plants. In the present study, various extracts of Pongamia pinnata leaves were tested against the head louse Pediculus humanus capitis. A filter paper diffusion method was conducted for determining the potential pediculocidal and ovicidal activity of chloroform, petroleum ether, methanol, and water extracts of P. pinnata leaves. The findings revealed that petroleum ether extracts possess excellent anti-lice activity with values ranging between 50.3% and 100% where as chloroform and methanol extracts showed moderate pediculocidal effects. The chloroform and methanol extracts were also successful in inhibiting nymph emergence and the petroleum ether extract was the most effective with a complete inhibition of emergence. Water extract was devoid of both pediculocidal and ovicidal activities. All the results were well comparable with benzoyl benzoate (25% w/v). These results showed the prospect of using P. pinnata leave extracts against P. humanus capitis in difficult situations of emergence of resistance to synthetic anti-lice agents.     

Analysis of Genetic Diversity in Pongamia [Pongamia pinnata (L) Pierrre] using AFLP Markers

In recent years, Pongamia has been considered as important renewable source of biodiesel, however not much molecular information is available in this species. Molecular characterization of this legume tree will enhance our understanding in improving the optimal yields of oil through breeding and enable us to meet the future demands for biodiesel. To assess the molecular genetic diversity in 46 Pongamia pinnata accessions collected from six different states of India, amplified fragment length polymorphism (AFLP) marker system was employed. Five AFLP primer combinations produced 520 discernible fragments, of which 502 (96.5%) were polymorphic. AFLP primer informativeness was estimated evaluating four parameters namely polymorphism information content (PIC), effective multiplex ratio (EMR), marker index (MI) and resolving power (RP). In total, 51 unique fragments were detected of which 19 unique fragments were observed with primer combination E-ACG / M-CTA. Although neighbour joining (NJ) method did not group accessions strictly according to their region of collection, a good level of genetic diversity was observed in examined germplasm. However, accessions collected from Karnataka showed comparatively higher diversity than accessions from other states. The diverse accessions identified in this study may be useful in Pongamia pinnata improvement to meet the future demands of biodiesel.     

Efficacy of karanjin and phorbol ester fraction against termites (Odontotermes obesus)

The non-edible oil seeds of Jatropha curcas (physic nut) and Pongamia pinnata (karanja) contain some toxic components (phorbol esters in J. curcas and karanjin in P. pinnata), which may be used as biopesticides. In this study, the active components of J. curcas and P. pinnata oil were extracted and their efficacy against the termites Odontotermes obesus (Rambur), was tested. The phorbol ester fraction of J. curcas and karanjin of P. pinnata oil were found to be effective against termites. A mortality rate of 100% was achieved in 6 h with karanjin and in 12 h with phorbol ester fraction. The LC₅₀ levels of karanjin and phorbol esters fractions were 0.038 and 0.071 g ml⁻¹, respectively, after 24 h at a 95% (0.05) confidence limit.     

Plant growth promoting bacteria enhance water stress resistance in green gram plants

Plant growth promoting bacterial (PGPB) strains Pseudomonas fluorescens Pf1 and endophytic Bacillus subtilis EPB5, EPB22, EPB 31 were tested for their capacity to induce water stress related proteins and enzymes in green gram (Vigna radiata) plants. Among the different bacteria used, P. fluorescens Pf1 increased the vigour index, fresh weight and dry weight of green gram seedlings in vitro. Quantitative and qualitative analyses of stress-related enzymes indicated the greater activity of catalase and peroxidase in green gram plants bacterized with P. fluorescens Pf1 against water stress when compared to untreated plants. The greater accumulation of proline was recorded in Pf1 treated plants compared to untreated plants. The pot culture study revealed the greater resistance to water stress by green gram plants treated with P. fluorescens Pf1 compared to untreated plants. The greater activity of stress-related enzymes in green gram plants mediated by PGPB could pave the way for developing drought management strategies.     

Bacterial membrane disrupting dodecapeptide SC4 improves survival of mice challenged with Pseudomonas aeruginosa

Background

Dodecapeptide SC4 is a broad-spectrum bactericidal agent that functions by disintegrating bacterial membranes and neutralizing endotoxins. For insight into which SC4 amino acids are functionally important, we assessed Gram-negative bactericidal effects in structure–activity relationship experiments. Subsequently, SC4 was tested in a murine bacteremia model to combine and compare the efficacy with Zosyn, a first-line antibiotic against Pseudomonas aeruginosa (P. aeruginosa).

Methods

SC4 alanine-scanning analogs and their activities on were tested on P. aeruginosa. Survival studies in P. aeruginosa challenged mice were executed to monitor overall efficacy of SC4 and Zosyn, as a single modality and also as combination treatment. ELISAs were used to measure blood serum levels of selected inflammatory cytokines during treatment.

Results

Cationic residues were found to play a crucial role in terms of bactericidal activity against P. aeruginosa. In vivo, while only 9% (3/34) of control animals survived to day two and beyond, 44% (12/27) to 41% (14/34) of animals treated with SC4 or Zosyn, respectively, survived beyond one week. Combination treatment of SC4 and Zosyn demonstrated improved survival, i.e. 60% (12/20). The TNFα, IL-1, and IL-6 serum levels were attenuated in each treatment group compared to the control group.

Conclusions

These data show that combination treatment of SC4 and Zosyn is most effective at killing P. aeruginosa and attenuating inflammatory cytokine levels in vivo.

General significance

Combination treatment of SC4 and Zosyn may be useful in the clinic as a more effective antibiotic therapy against Gram-negative infectious diseases.     

Microwave assisted alkali-catalyzed transesterification of Pongamia pinnata seed oil for biodiesel production

In this study, microwave assisted transesterification of Pongamia pinnata seed oil was carried out for the production of biodiesel. The experiments were carried out using methanol and two alkali catalysts i.e., sodium hydroxide (NaOH) and potassium hydroxide (KOH). The experiments were carried out at 6:1 alcohol/oil molar ratio and 60 °C reaction temperature. The effect of catalyst concentration and reaction time on the yield and quality of biodiesel was studied. The result of the study suggested that 0.5% sodium hydroxide and 1.0% potassium hydroxide catalyst concentration were optimum for biodiesel production from P. pinnata oil under microwave heating. There was a significant reduction in reaction time for microwave induced transesterification as compared to conventional heating.     

Plant Growth-Promoting Bacteria Facilitate the Growth of Barley and Oats in Salt-Impacted Soil: Implications for Phytoremediation of Saline Soils

Plant growth-promoting bacteria (PGPB) strains that contain the enzyme 1-amino- cyclopropane-1-carboxylate (ACC) deaminase can lower stress ethylene levels and improve plant growth. In this study, ACC deaminase-producing bacteria were isolated from a salt-impacted (～50 dS/m) farm field, and their ability to promote plant growth of barley and oats in saline soil was investigated in pouch assays (1% NaCl), greenhouse trials (9.4 dS/m), and field trials (6–24 dS/m). A mix of previously isolated PGPB strains UW3 (Pseudomonas sp.) and UW4 (P. sp.) was also tested for comparison. Rhizobacterial isolate CMH3 (P. corrugata) and UW3+UW4 partially alleviated plant salt stress in growth pouch assays. In greenhouse trials, CMH3 enhanced root biomass of barley and oats by 200% and 50%, respectively. UW3+UW4, CMH3 and isolate CMH2 also enhanced barley and oat shoot growth by 100%–150%. In field tests, shoot biomass of oats tripled when treated with UW3+UW4 and doubled with CHM3 compared with that of untreated plants. PGPB treatment did not affect salt uptake on a per mass basis; higher plant biomass led to greater salt uptake, resulting in decreased soil salinity. This study demonstrates a method for improving plant growth in marginal saline soils. Associated implications for salt remediation are discussed.     

Influence of clove oil on certain quorum-sensing-regulated functions and biofilm of Pseudomonas aeruginosa and Aeromonas hydrophila

Quorum sensing (QS) plays an important role in virulence, biofilm formation and survival of many pathogenic bacteria including Pseudomonas aeruginosa. This signalling pathway is considered as novel and promising target for anti-infective agents. In the present investigation, effect of the Sub-MICs of clove oil on QS regulated virulence factors and biofilm formation was evaluated against P. aeruginosa PAO1 and Aeromonas hydrophila WAF-38 strain. Sub-inhibitory concentrations of the clove oil demonstrated statistically significant reduction of las- and rhl-regulated virulence factors such as LasB, total protease, chitinase and pyocyanin production, swimming motility and exopolysaccharide production. The biofilm forming capability of PAO1 and A. hydrophila WAF-38 was also reduced in a concentration-dependent manner at all tested sub-MIC values. Further, the PAO1-preinfected Caenorhabditis elegans displayed an enhanced survival when treated with 1.6% v/v of clove oil. The above findings highlight the promising anti-QS-dependent therapeutic function of clove oil against P. aeruginosa.     

Investigation of saturated and aromatic hydrocarbon resistance mechanisms in Pseudomonas aeruginosa IBBML1

Pseudomonas aeruginosa IBB_ML1, isolated from Poeni petroleum sludge, was able to tolerate and degrade both saturated (n-hexane, n-heptane, n-hexadecane, cyclohexane) and aromatic (benzene, ethylbenzene, propylbenzene, xylene isomers, styrene) hydrocarbons. Molecular studies have revealed that the high hydrocarbon resistance of Pseudomonas aeruginosa IBB_ML1 could be due to the action of members of the HAE1 (hydrophobe/amphiphile efflux 1) family of transporters. It is further possible that additional mechanisms may account for the tolerance of Pseudomonas aeruginosa IBB_ML1 to hydrocarbons, and a combination of short-term and long-term mechanisms may act together in the adaptation of Pseudomonas aeruginosa IBB_ML1 cells to saturated and aromatic hydrocarbons. β-galactosidase activity measurements revealed that there was significant induction of the lacZ gene in Pseudomonas aeruginosa IBB_ML1 cells grown in the presence of either 5% and 10% (v/v) saturated or aromatic hydrocarbons, compared with control (cells incubated without hydrocarbons). Rhodamine 6G accumulation in Pseudomonas aeruginosa IBB_ML1 cells grown in the presence of 5% and 10% (v/v) saturated hydrocarbons was higher than rhodamine 6G accumulation in cells grown in the presence of 5% and 10% (v/v) aromatic hydrocarbons. The study of cellular and molecular modifications to Pseudomonas aeruginosa IBB_ML1 induced by 5% and 10% (v/v) saturated and aromatic hydrocarbons revealed a complex response of bacterial cells to the presence of different hydrophobic substrates in the culture medium.     

Nuclear DNA content of Pongamia pinnata L. and genome size stability of in vitro-regenerated plantlets

Pongamia pinnata L. is a multipurpose versatile legume that is well known as a prospective feedstock biodiesel species. However, to date, there has been little genomic research aimed at the exploitation of the biotechnological potential of this species. Genetic characterization of any plant is a challenging task when there is no information about the genome size and organization of the species. Therefore, the genome size of P. pinnata was estimated by flow cytometry with respect to two standards (Zea mays and Pisum sativum), and compared with that of in vitro-raised plants (nodal segment, in vitro-rooted plantlets and acclimatized in vitro plants) to study the potential effect of somaclonal variation on genome size. This method can be used to support the establishment of true-to-type plants to encourage afforestation programs. Modified propidium iodide/hypotonic citrate buffer was used for isolation of the intact nuclei. The 2C DNA value of this species was estimated to be 2.51?±?0.01 pg. Statistically, there was no significant difference in the DNA content of the in vitro-grown plants and mother plant at α?=?0.05. As a result of the low genome size of P. pinnata, a species that has adapted itself to a wide range of edaphic and ecological condition, we can now proceed for its next generation sequencing and genomic diversity studies.     

Multi-substrate biodegradation kinetics of MTBE and BTEX mixtures by Pseudomonas aeruginosa

Biodegradation of MTBE under various multi-substrate conditions by Pseudomonas aeruginosa was investigated in this research. The addition of BTEX in various combinations significantly inhibited MTBE biodegradation. This result was mainly due to the non-competitive inhibition between MTBE and BTEX compounds. The rate of MTBE biodegradation decreased with the increasing substrate number for multi-substrate conditions. Additionally, the kinetic models developed in this research successfully simulate the degradation of MTBE under various multi-substrate conditions. However, the accumulation of TBA during MTBE biodegradation revealed that P. aeruginosa was unable to degrade TBA during the period of time tested.     

Microbial Cells as Biosorbents for Heavy Metals: Accumulation of Uranium by Saccharomyces cerevisiae and Pseudomonas aeruginosa

Uranium accumulated extracellularly on the surfaces of Saccharomyces cerevisiae cells. The rate and extent of accumulation were subject to environmental parameters, such as pH, temperature, and interference by certain anions and cations. Uranium accumulation by Pseudomonas aeruginosa occurred intracellularly and was extremely rapid (<10 s), and no response to environmental parameters could be detected. Metabolism was not required for metal uptake by either organism. Cell-bound uranium reached a concentration of 10 to 15% of the dry cell weight, but only 32% of the S. cerevisiae cells and 44% of the P. aeruginosa cells within a given population possessed visible uranium deposits when examined by electron microscopy. Rates of uranium uptake by S. cerevisiae were increased by chemical pretreatment of the cells. Uranium could be removed chemically from S. cerevisiae cells, and the cells could then be reused as a biosorbent.     

Effect of biosurfactant and fertilizer on biodegradation of crude oil by marine isolates of Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa

This study was conducted to investigate the effects of fertilizers and biosurfactants on biodegradation of crude oil by three marine bacterial isolates; Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa. Five sets of experiments were carried out in shake flask and microcosm conditions with crude oil as follows: Set 1-only bacterial cells added (no fertilizer and biosurfactant), Set 2-with additional fertilizer only, Set 3-with additional biosurfactant only, Set 4-with added biosurfactant + fertilizer, Set 5-with no bacterial cells added (control), all the above experimental sets were incubated for 168 h. The biosurfactant + fertilizer added Set 4, resulted in maximum crude oil degradation within shake flask and microcosm conditions. Among the three bacterial isolates, P. aeruginosa and biosurfactant produced by this strain resulted in maximum crude oil degradation compared to the other two bacterial strains investigated. Interestingly, when biosurfactant and bacterial cells were used (Set 3), significant oil biodegradation activity occurred and the difference between this treatment and that in Set 4 with added fertilizer + biosurfactant were only 4-5% higher degradation level in shake flask and 3.2-7% in microcosm experiments for all three bacterial strains used. It is concluded that, biosurfactants alone capable of promoting biodegradation to a large extent without added fertilizers, which will reduce the cost of bioremediation process and minimizes the dilution or wash away problems encountered when water soluble fertilizers used during bioremediation of aquatic environments.     

Plant growth promoting potentials of Pseudomonas spp. strain OG isolated from marine water

Abstract

Bacterium Pseudomonas spp. olive green (OG) was isolated from marine water, yet, it was characterized as plant growth promoting bacterium (PGPB). Multiple plant growth promoting traits of OG isolate were determined in vitro. It was tested positive for Indole-3-acetic acid (IAA) production with 29 µg ml^?1 of IAA yield, phosphate solubilization with 34 µg ml^?1 solubilization of Tri-calcium-phosphate and it showed maximum of 32 µg ml^?1 of ammonia production. OG isolate was affirming siderophore production, hydrocyanic acid (HCN) production and catalase production. 16S rRNA gene sequence comparison was used to identify the isolate which showed its closest neighbor to be Pseudomonas fluoroscens strain BCPBMS-1. Efficacy of this PGPB was tested on the seedling growth of two test plants chickpea and green gram. Both the test plants treated with OG-based talc bioformulation showed significant growth promotion. Chickpea showed enhanced overall fresh biomass by 24%, overall dry biomass by 27% was observed after 15 days of seeded in pots. Green gram showed enhanced overall dry biomass by 28% was observed after 10 days of seeded in pots.     

cbb3-Type Cytochrome c Oxidases,Aerobic Respiratory Enzymes,Impact the Anaerobic Life of Pseudomonas aeruginosa PAO1

For bacteria, many studies have focused on the role of respiratory enzymes in energy conservation; however, their effect on cell behavior is poorly understood. Pseudomonas aeruginosa can perform both aerobic respiration and denitrification. Previous studies demonstrated that cbb₃-type cytochrome c oxidases that support aerobic respiration are more highly expressed in P. aeruginosa under anoxic conditions than are other aerobic respiratory enzymes. However, little is known about their role under such conditions. In this study, it was shown that cbb₃ oxidases of P. aeruginosa PAO1 alter anaerobic growth, the denitrification process, and cell morphology under anoxic conditions. Furthermore, biofilm formation was promoted by the cbb₃ oxidases under anoxic conditions. cbb₃ oxidases led to the accumulation of nitric oxide (NO), which is produced during denitrification. Cell elongation induced by NO accumulation was reported to be required for robust biofilm formation of P. aeruginosa PAO1 under anoxic conditions. Our data show that cbb₃ oxidases promote cell elongation by inducing NO accumulation during the denitrification process, which further leads to robust biofilms. Our findings show that cbb₃ oxidases, which have been well studied as aerobic respiratory enzymes, are also involved in denitrification and influence the lifestyle of P. aeruginosa PAO1 under anoxic conditions.     

Suppression of bacterial wilt in Eucalyptus urophylla by fluorescent Pseudomonas spp. in China

Bacterial wilt caused by Ralstonia solanacearum race 1, biovar III has become a severe problem in Eucalyptus plantations in south China. The disease mainly attacks young eucalypt trees, and no effective control measures are available yet. To explore possibilities to develop biological control of the disease, strains of fluorescent Pseudomonas spp. that are effective in suppressing plant diseases by known mechanisms, were tested for their potential to control bacterial wilt in Eucalyptus. Pseudomonas putida WCS358r, Pseudomonas fluorescens WCS374r, P. fluorescens WCS417r, and Pseudomonas aeruginosa 7NSK2 antagonize R. solanacearum in vitro by siderophore-mediated competition for iron, whereas inhibition of pathogen growth by P. fluorescens CHA0r is antibiosis-based. No correlations were found between antagonistic activities of these Pseudomonas spp. in vitro and biocontrol of bacterial wilt in Eucalyptus in vivo. None of the strains suppressed disease when mixed together with the pathogen through the soil or when seeds or seedlings were treated with the strains one to four weeks before transfer into soil infested with R. solanacearum. However, when the seedlings were dipped with their roots in a bacterial suspension before transplanting into infested soil, P. fluorescens WCS417r significantly suppressed bacterial wilt. P. putida WCS358r was marginally effective, whereas its siderophore-minus mutant had no effect at all, indicating that siderophore-mediated competition for iron can contribute but is not effective enough to suppress bacterial wilt in Eucalyptus. A derivative of P. putida WCS358r, constitutively producing 2,4-diacetylphloroglucinol (WCS358::phl) reduced disease. Combined treatment with P. fluorescens WCS417r and P. putida WCS358::phl did not improve suppression of bacterial wilt.