In vitro regeneration from different ages of petioles of physic nut (Jatropha curcas L.)

Jatropha curcas L. is an important non-edible oil yielding plant growing in wasteland and dry lands. The experiment was conducted to study the plant regeneration of J. curcas from different ages of petioles. Petioles explant grown on Murashige and Skoog’s (MS) medium supplemented with 1 mg/l α-naphthalene acetic acid and 0.2 mg/l kinetin showed the highest frequency of callus induction and the same medium was found to be best suited for callus growth in 1st petiole. Percent of somatic embryo formation was higher (35.16%) from the 1st petiole explant on 0.5 mg/l thidiazuron with 0.4 mg/l gibberellic acid. MS medium supplemented with 1 mg/l N6-benzylaminopurine, 0.5 mg/l indole-3-acetic acid, 0.25 mg/l kinetin recorded the higher somatic embryo germination percentage (66.85%). MS basal medium supplemented with 0.5 mg/l thidiazuron, 0.1 mg/l N6-benzylaminopurine, 0.4 mg/l gibberellic acid was found to be best medium for shoot elongation. Among the auxins tested, the higher frequency of root formation was observed in MS medium supplemented with 0.3 mg/l α-naphthalene acetic acid compared to indole-3-butyric acid and indole-3-acetic acid. The survival rate of in vitro rooted plantlets was dependent on the type of explant source and it varies from 47 to 60%.Keywords: Euphorbiaceae, petiole, callus, indirect organogenesis, biodiesel, plant growth regulatorAfrican Journal of Biotechnology, Vol. 13(2), pp. 265-273, 8 January, 201

Plant Growth Promoting of Endophytic Sporosarcina aquimarina

Endophytic Sporosarcina aquimarina SjAM16103 was isolated from the inner tissues of pneumatophores of mangrove plant Avicennia marina along with Bacillus sp. and Enterobacter sp. Endophytic S. aquimarina SjAM16103 was Gram variable, and motile bacterium measured 0.6–0.9 μm wide by 1.7–2.0 μm long and light orange-brown coloured in 3-day cultures on tryptone broth at 26°C. Nucleotide sequence of this strain has been deposited in the GenBank under accession number GU930359. This endophytic bacterium produced 2.37 μMol/mL of indole acetic acid and siderophore as it metabolites. This strain could solubilize phosphate molecules and fixes atmospheric nitrogen. Endophytic S. aquimarina SjAM16103 was inoculated into four different plants under in vitro method to analyse its growth-promoting activity and role inside the host plants. The growth of endophytic S. aquimarina SjAM16103 inoculated explants were highly significant than the uninoculated control explants. Root hairs and early root development were observed in the endophytic S. aquimarina SjAM16103 inoculated explants

Polyphosphate-accumulating organisms in full-scale tropical wastewater treatment plants use diverse carbon sources

Enhanced biological phosphorus removal (EBPR) is considered challenging in the tropics, based on a great number of laboratory-based studies showing that the polyphosphate-accumulating organism (PAO) Candidatus Accumulibacter does not compete well with glycogen accumulating organisms (GAOs) at temperatures above 25 °C. Yet limited information is available on the PAO community and the metabolic capabilities in full-scale EBPR systems operating at high temperature. We studied the composition of the key functional PAO communities in three full-scale wastewater treatment plants (WWTPs) with high in-situ EBPR activity in Singapore, their EBPR-associated carbon usage characteristics, and the relationship between carbon usage and community composition. Each plant had a signature community composed of diverse putative PAOs with multiple operational taxonomic units (OTUs) affiliated to Ca. Accumulibacter, Tetrasphaera spp., Dechloromonas and Ca. Obscuribacter. Despite the differences in community composition, ex-situ anaerobic phosphorus (P)-release tests with 24 organic compounds from five categories (including four sugars, three alcohols, three volatile fatty acids (VFAs), eight amino acids and six other carboxylic acids) showed that a wide range of organic compounds could potentially contribute to EBPR. VFAs induced the highest P release (12.0-18.2 mg P/g MLSS for acetate with a P release-to-carbon uptake (P:C) ratio of 0.35-0.66 mol P/mol C, 9.4-18.5 mg P/g MLSS for propionate with a P:C ratio of 0.38-0.60, and 9.5-17.3 mg P/g MLSS for n-butyrate), followed by some carboxylic acids (10.1-18.1 mg P/g MLSS for pyruvate, 4.5-11.7 mg P/g MLSS for lactate and 3.7-12.4 mg P/g MLSS for fumarate) and amino acids (3.66-7.33 mg P/g MLSS for glutamate with a P:C ratio of 0.16-0.43 mol P/mol C, and 4.01-7.37 mg P/g MLSS for aspartate with a P:C ratio of 0.17-0.48 mol P/mol C). P-release profiles (induced by different carbon sources) correlated closely with PAO community composition. High micro-diversity was observed within the Ca. Accumulibacter lineage, which represented the most abundant PAOs. The total population of Ca. Accumulibacter taxa was highly correlated with P-release induced by VFAs, highlighting the latter's importance in tropical EBPR systems. There was a strong link between the relative abundance of individual Ca. Accumulibacter OTUs and the extent of P release induced by distinct carbon sources (e.g., OTU 81 and amino acids, and OTU 246 and ethanol), suggesting niche differentiation among Ca. Accumulibacter taxa. A diverse PAO community and the ability to use numerous organic compounds are considered key factors for stable EBPR in full-scale plants at elevated temperatures.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore

Micropropagation of <i style="">Sauropus androgynus </i>(L.) Merr.—An important green leafy vegetable

235-237A micropropagation protocol has been developed for Sauropus androgynus (L.) Merr. using uninodal explants in Murashige and Skoog (MS) medium supplemented with various concentrations of cytokinins, benzyl adenine (BA) and kinetin (Kn). Shoot induction was observed in 1.0 mg/L BA and 0.1 mg/L Kn after 25 d and more number of shoots was achieved in shoot induction medium. Rooting was induced from shoots in MS medium supplemented with various concentrations of indole 3-butyric acid (IBA) and naphthalene acetic acid (NAA). All the shoots were rooted in 0.5 mg/L IBA and 0.2 mg/L NAA after 25 d. Rooted plants were transferred to soil and successfully acclimatized

Influence of altitudinal variation on the anti-oxidant capacity of essential oil of Syzygium densiflorum from Southern Western Ghats, India

Background: Syzygium densiflorum is a vulnerable tree species belonging to the Myrtaceae family. Objective: To investigate the influence of altitudinal variation on the anti-oxidant potential of leaf essential oil of Syzygium densiflorum. Materials and Methods: The leaf essential oil has been isolated using hydrodistillation process and their scavenging ability was determined using five in vitro assays such as 2, 2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing anti-oxidant power (FRAP), 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), hydrogen peroxide (H 2 O 2 ) and hydroxyl radical scavenging assays. Statistical analysis: The results were analysed statistically using one-way analysis of variance (ANOVA) following Duncan′s multiple range test. Results: Leaves from lower altitude showed higher activity against hydrogen peroxide, hydroxyl radical and ferric ion and moderate activity against DPPH and ABTS free radicals. Leaves from higher altitude essential oil exhibits potent activity against hydrogen peroxide and hydroxyl radical compared with the standard. Conclusions: Comparatively lower altitude leaf essential oil showed potent anti-oxidant activity confirming the fact that altitudinal variations have profound effect on the anti-oxidant potential of Syzygium densiflorum

Loss of the acetate switch in Vibrio vulnificus enhances predation defense against Tetrahymena pyriformis

Vibrio vulnificus is an opportunistic human pathogen and autochthonous inhabitant of coastal marine environments, where the bacterium is under constant predation by heterotrophic protists or protozoans. As a result of this selection pressure, genetic variants with antipredation mechanisms are selected for and persist in the environment. Such natural variants may also be pathogenic to animal or human hosts, making it important to understand these defense mechanisms. To identify antipredator strategies, 13 V. vulnificus strains of different genotypes isolated from diverse environments were exposed to predation by the ciliated protozoan Tetrahymena pyriformis, and only strain ENV1 was resistant to predation. Further investigation of the cell-free supernatant showed that ENV1 acidifies the environment by the excretion of organic acids, which are toxic to T. pyriformis. As this predation resistance was dependent on the availability of iron, transcriptomes of V. vulnificus in iron-replete and iron-deplete conditions were compared. This analysis revealed that ENV1 ferments pyruvate and the resultant acetyl-CoA leads to acetate synthesis under aerobic conditions, a hallmark of overflow metabolism. The anaerobic respiration global regulator arcA was upregulated when iron was available. An ΔarcA deletion mutant of ENV1 accumulated less acetate and, importantly, was sensitive to grazing by T. pyriformis. Based on the transcriptome response and quantification of metabolites, we conclude that ENV1 has adapted to overflow metabolism and has lost a control switch that shifts metabolism from acetate excretion to acetate assimilation, enabling it to excrete acetate continuously. We show that overflow metabolism and the acetate switch contribute to prey-predator interactions. IMPORTANCE Bacteria in the environment, including Vibrio spp., interact with protozoan predators. To defend against predation, bacteria evolve antipredator mechanisms ranging from changing morphology, biofilm formation, and secretion of toxins or virulence factors. Some of these adaptations may result in strains that are pathogenic to humans. Therefore, it is important to study predator defense strategies of environmental bacteria. V. vulnificus thrives in coastal waters and infects humans. Very little is known about the defense mechanisms V. vulnificus expresses against predation. Here, we show that a V. vulnificus strain (ENV1) has rewired the central carbon metabolism, enabling the production of excess organic acid that is toxic to the protozoan predator T. pyriformis. This is a previously unknown mechanism of predation defense that protects against protozoan predators.Ministry of Education (MOE)National Research Foundation (NRF)Published versionWe acknowledge support from the iThree Institute at the University of Technology Sydney, Sydney, Australia, the Australian Research Council Discovery Project (DP170100453) and by the National Research Foundation and Ministry of Education Singapore under its Research Centre of Excellence Program to the Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University

Global warming readiness: Feasibility of enhanced biological phosphorus removal at 35 °C

Recent research has shown enhanced biological phosphorus removal (EBPR) from municipal wastewater at warmer temperatures around 30 °C to be achievable in both laboratory-scale reactors and full-scale treatment plants. In the context of a changing climate, the feasibility of EBPR at even higher temperatures is of interest. We operated two lab-scale EBPR sequencing batch reactors for > 300 days at 30 °C and 35 °C, respectively, and followed the dynamics of the communities of polyphosphate accumulating organisms (PAOs) and competing glycogen accumulating organisms (GAOs) using a combination of 16S rRNA gene metabarcoding, quantitative PCR and fluorescence in situ hybridization analyses. Stable and nearly complete phosphorus (P) removal was achieved at 30 °C; similarly, long term P removal was stable at 35 °C with effluent PO43-_P concentrations 43−-P ratio (from 25:1 to 40:1) effectively eased the carbon deficiency and benefited PAOs. In general, a slow-feeding strategy and sufficiently high carbon input benefited a high and stable EBPR at 35 °C, representing basic conditions suitable for full-scale treatment plants experiencing higher water temperatures.</p