Identification and feeding characteristics of the mixotrophic flagellate Poterioochromonas malhamensis, a microalgal predator isolated from planting water of Pontederia cordata.

The microorganisms and allelochemicals in Pontederia cordata planting water may have a synergistic inhibitory effect on algae. To study this synergy, an algae-inhibiting organism was isolated and identified, and its growth and feeding characteristics were studied. The organism was identified as Poterioochromonas malhamensis yzs924 based on both its morphology and molecular barcoding employing 18S rDNA gene sequences.The growth and feeding of P. malhamensis were affected by environmental factors and the state of its prey. (1) P. malhamensis is a mixotrophic flagellate. Its heterotrophic growth was the fastest in a wheat grain medium, and its growth rate in this study reached 2.5 day-1. (2) Within a short period of time (2 days), P. malhamensis growth was slower under continuous dark conditions than under alternating light and dark conditions, but it fed on Microcystis aeruginosa more rapidly under dark conditions. (3) High pH was disadvantageous to the growth and grazing of P. malhamensis. When the pH was kept stable at 9, P. malhamensis could not grow continuously. (4) When the initial density of M. aeruginosa was 5 × 107 cells/mL or is in a period of decline, P. malhamensis could not remove all M. aeruginosa. The combined use of P. malhamensis and allelochemicals may represent a method of M. aeruginosa control, but this approach requires further research.

Reduced pests, improved grain quality and greater total income: benefits of intercropping rice with Pontederia cordata.

BACKGROUND: Intercropping, which is growing two or more different crops in the same field simultaneously, is an effective traditional agricultural practice for productivity, resource utilization, and pest control. However, study on intercropping in paddy fields is limited. So in this study, field experiments of 2 years/four seasons (early and late seasons in 2016 and 2017) were conducted to examine the effects of rice-Pontederia cordata intercropping on rice plant growth, pest control, yield, income, and grain quality. RESULTS: We found rice-P. cordata intercropping significantly decreased the occurrence of rice diseases and pests, with a 22.0-45.9% reduction in sheath blight and a 33.8-34.4% reduction in leaf folders. The mean land equivalent ratio (LER) (1.09) result indicates that intercropping rice and P. cordata generated positive yield effects. In addition, due to the economic profit from the replacement stripe of P. cordata in the rice paddy field, intercropping rice with P. cordata could greatly enhance farmer income. The average total income of rice intercropped with P. cordata was 2.5-fold higher than that of rice monoculture. Furthermore, intercropping significantly improved grain quality compared with the rice monoculture. It significantly increased the milled rice rate and whole milled rice rate by 11.2% and 12.8%, respectively, but decreased the chalky rice rate by 30.9-39.8% and chalkiness degree by 32.2%. CONCLUSIONS: We suggest that rice-P. cordata intercropping provides an environmentally effective way to control rice diseases and pests, results in higher overall productivity and total income, and improves grain quality. © 2021 Society of Chemical Industry.

Effects of aqueous extracts from the rhizome of Pontederia cordata on the growth and interspecific competition of two algal species.

Single and co-culture systems of Microcystis aeruginosa and Scenedesmus obliquus were prepared with different initial algal densities and treated with different concentrations of aqueous extracts from the rhizome of Pontederia cordata to study its inhibitory effect on algal growth and the competitive relationship between these two algal species. The results showed that aqueous extracts could inhibit the growth of M. aeruginosa and S. obliquus, and the inhibition rate of aqueous extracts on the growth of M. aeruginosa was always higher than that of S. obliquus. A Lotka-Volterra competition model revealed that these two algal species can co-exist without the addition of aqueous extracts, and S. obliquus exhibited a stronger ability to compete than that of M. aeruginosa. Meanwhile, the dominant algal species changed with the addition of aqueous extracts regardless of the initial ratios of the two algae. The species ratio of mixed cultures had a strong effect on the interspecific interaction between the two algae. The higher proportion of S. obliquus in the initial proportion of two algae, the stronger competitive ability of S. obliquus when compared with that of M. aeruginosa.

Inhibitory effects of Pontederia cordata on the growth of Microcystis aeruginosa.

This study investigated the effect of Pontederia cordata on Microcystis aeruginosa growth in three different experimental settings: (i) co-cultivation, (ii) exposure of cyanobacteria to culture water of P. cordata, and (iii) exposure of M. aeruginosa to organic extracts of P. cordata. Results showed that the growth of M. aeruginosa was significantly inhibited by co-cultivation, with the highest inhibition rate of 61.9% within 5 days. Moreover, 95% culture water with P. cordata could markedly inhibit the growth of M. aeruginosa, with inhibition rate of 98.3% on day 6, indicating that most of the algal cells died. The organic extracts of fibrous root showed stronger inhibition effect than the leaf and stalk extracts. Acetone extract of fibrous root showed the strongest inhibitory effect on M. aeruginosa. Different components of 80% acetone extracts from fibrous root exhibited varied effects on the growth of M. aeruginosa. Ethyl acetate and water components had strong inhibition effects on M. aeruginosa. By contrast, n-butyl alcohol components had weak inhibition effects, and hexane components even promoted the growth of M. aeruginosa. Allelochemicals of P. cordata were primarily released into the water through the fibrous root. Results indicated that P. cordata can be applied in environmentally friendly algal inhibition.

Evaluation of phytoconstituents and anti-nephrotoxic and antioxidant activities of Monochoria vaginalis.

Monochoria vaginalis is an herbaceous medicinal plant used to treat, liver problems India. Acetaminophen is a commonly used analgesic and antipyretic agent which, at high doses, causes liver and kidney necrosis in man and animals. The aim of the present study is to evaluate phytoconstituents and investigate the nephroprotective & antioxidant activities of the ethanol extract of Monochoria vaginalis on acetaminophen induced toxicity in rats. Phytoconstituents like n-hexadecanoic acid, 3-methyl- acetate-1-butanol, 1,1,3-triethoxy- propane, Z,Z,Z-1,4,6,9 - nonadecatetraene, undecanoic acid, 3-trifluoroacetoxy penta decane and 4-ethyl-5-octyl-2,2-bis (trifluoromethyl) - cis-1,3-dioxalone were identified from ethanol extract of Monochoria vaginalis by using a gas chromatograph-mass spectrograph (GC MS). Biochemical studies show that there is an increase in the levels of serum urea and creatinine along with an increase in the body weight and reduction in the levels of uric acid in acetaminophen induced groups. These values are retrieved significantly by treatment with Monochoria vaginalis extracts at two different doses. The antioxidant studies reveal that the levels of renal SOD, CAT, GSH and GPx in the APAP treated animals are increased significantly along with a reduced MDA content in ethanol extract of Monochoria vaginalis treated groups. Apart from these, histopathological changes also reveal the protective nature of the Monochoria vaginalis extract against acetaminophen induced necrotic damage of renal tissues. In conclusion, these data suggest that the ethanol extract of Monochoria vaginalis can prevent renal damage from APAP induced nephrotoxicity in rats and it is likely to be mediated through active phytoconstituents and its antioxidant activities.

[A isolation and identification of an antioxidant from Monochoria vaginalis].

With solvent extraction, a total of four fractions were separated from 75% alcohol extract of Monochoria vaginalis, and their antioxidative activities were measured by iodine method. The results showed that among the fractions, n-butanol fraction exhibited the highest antioxidative activity, which was not only significantly higher than CK (water), but also equivalent to the natural antioxidant tea polyphenols and synthetic antioxidant butylated hydroxyl toluene (BHT). A compound was isolated from the n-butanol fraction by using column chromatography, and identified as stigmasterol 3-O-beta-D-glucopyranoside. Its antioxidative activity estimated by the determination of the percentage of scavenged free radicals indicated that this compound exhibited a higher activity than BHT in scavenging free radicals.

Monolaterol, the first configurationally assigned phenylphenalenone derivative with a stereogenic center at C-9, from Monochoria elata.

Phytochemical analysis of the roots of Monochoria elata resulted in the structure elucidation of monolaterol, the first configurationally assigned phenylphenalenone-type natural product with a stereogenic center at the phenyl-bearing carbon, C-9, and four known phenylphenalenones by MS and NMR methods. The absolute configuration of the new phenyldihydrophenalenediol was assigned by comparing the results of quantum chemical CD calculations and experimental CD spectra, and the crystal structure was determined by X-ray diffraction analysis.

Variation of nutrient and metal concentrations in aquatic macrophytes along the Rio Cachoeira in Bahia (Brazil).

The use of cuprous fungicides in cocoa production in the southern part of the state of Bahia (Brazil) for decades has caused an accumulation of copper in various components of the cocoa plantations, and a contamination of regional freshwater ecosystems is suspected. Urban and industrial sources are supposed to contribute to water pollution and eutrophication of the Rio Cachoeira, the main river in this region. In order to study the metal contamination and nutritional status of this freshwater ecosystem, samples of the aquatic macrophytes Eichhornia crassipes and Pistia stratiotes were collected at seven sites along the river course. The samples were analysed for their copper, aluminium, chromium, nitrogen and phosphorus concentrations. The levels of heavy metals increased in the downstream direction, particularly in the roots of water hyacinth. A dramatic increase of nitrogen and phosphorus concentrations in water as well as in plant tissues was found in samples collected downstream from the city of Itabuna. Metal input and eutrophication were attributed to agricultural, industrial and urban sources in the region. Biomonitoring of the water quality using aquatic macrophytes as accumulative indicator plants is recommended in addition to chemical water analyses.

Treatment of dairy waste by using water hyacinth.

In the present study treatment of wastewater from a large dairy by using water hyacinth was studied in laboratory experiments. Effects of depth of the system, variations in area coverage, prior settling and of daily renewal of the plants was also studied on the efficacy of hyacinth in treating the dairy waste. Water hyacinth (Eichhornia crassipes) was found to grow exceptionally well in the waste (BOD 840.0 mg/L) and brought down the level of BOD from 840.0 to 121.0 mg/L; COD from 1,160.0 to 164.0 mg/L, total suspended solids from 359.0 mg/L to 245.0 mg/L, TDS from 848.0 mg/L to 352.0 mg/L, total nitrogen from 26.6 mg/L to 8.9 mg/L in 4 days. There was very little reduction, however in calcium, sodium and potassium concentration. Results of different experiments showed that systems with shallow depth were more efficient in removing dissolved solids, suspended solids, BOD, COD, nitrogen and phosphorus. Daily renewal of the plants led to slightly better reduction in suspended and dissolved solids, BOD, COD and nitrogen. Water hyacinth coverage was found to have a direct bearing on the treatment efficiency. Pretreatment (settling) of the waste was also found to be favourable as dissolved oxygen content increased rapidly in the experimental sets with pretreatment. Efficiency of removal of various parameters was also good in these sets. From the study it can be concluded that dairy waste can be effectively treated by water hyacinth. Consideration of above parameters and incorporating them in design factors can greatly increase the efficiency of the system.

Field, laboratory, and X-ray absorption spectroscopic studies of mercury accumulation by water hyacinths.

We have studied water hyacinth (Eichhornia crassipes), a non-native nuisance plant found in the in San Francisco Bay Delta region, for its potential to phytoremediate mercury. Mercury is a common contaminant in San Francisco Bay Area waters because of gold mining activities. In this study, speciation of mercury in hyacinth roots and shoots, rates of mercury uptake by hyacinths in the laboratory, and mercury levels near the Big Break Region in the Delta were studied. In the speciation studies, Hg L3 edge X-ray absorption spectroscopic analysis of Hg model compounds and water hyacinth roots and shoots revealed that Hg was initially bound ionically to oxygen ligands in roots, most likely to carboxylate groups, and was bound covalently to sulfur groups in shoots. In laboratory uptake studies, we found that water hyacinths grown in 1 ppm Hg and one-quarter strength Hoagland's solution accumulated a maximum of 0.20 ppm in shoots and 16.0 ppm in roots, both reaching maximum concentrations after approximately 16 days. Mercury concentrations were found to be 0.26 +/- 0.20 ppm in the water and 0.86 +/- 1.70 ppm in sediment at Big Break. It was proposed that water hyacinths have the potential to phytoremediate mercury in the water at Big Break if the current herbicide treatments are replaced by physical removal.