Reduction in Salt Stress Due to the Action of Halophilic Bacteria That Promote Plant Growth in Solanum lycopersicum.

Soil salinity is one of the most important factors reducing agricultural productivity worldwide. Halophilic plant growth-promoting bacteria (H-PGPB) represent an alternative method of alleviating saline stress in crops of agricultural interest. In this study, the following halophilic bacteria were evaluated: Bacillus sp. SVHM1.1, Halomonas sp. SVCN6, Halomonas sp. SVHM8, and a consortium. They were grown under greenhouse conditions in Solanum lycopersicum at different salinity concentrations in irrigation water (0, 20, 60, and 100 mM NaCl) to determine the effects on germination, fruit quality, yield, and concentration of osmoprotectors in plant tissue. Our results demonstrate the influence of halophilic bacteria with the capacity to promote plant growth on the germination and development of Solanum lycopersicum at higher salinity levels. The germination percentage was improved at the highest concentration by the inoculated treatments (from 37 to 47%), as were the length of the radicle (30% at 20 mM) and plumule of the germinated seed, this bacterium also increased the weight of the plumule (97% at 100 mM). They also improved the yield. The dry weight of the plant, in addition to having an influence on the quality of the fruit and the concentration of osmoprotectors (Bacillus sp. SVHM 1.1) had the greatest effect on fruit yield (1.5 kg/plant at 20 mM), by the otherhand, Halomonas sp. SVHM8 provided the best fruit quality characteristics at 100 mM. According to the above results, the efficiency of halophilic PGPB in the attenuation of salt stress in Solanum lycopersicum has been proven.

Identification of Halophilic and Halotolerant Bacteria from the Root Soil of the Halophyte Sesuvium verrucosum Raf.

Soil salinity is a condition that limits crop growth and productivity, and soil-dwelling bacteria from halophytic plant roots may be a viable strategy to cope with low productivity due to salt stress. Halophilic and halotolerant bacteria of the root soil of Sesuvium verrucosum were analyzed in this study as there is little evidence regarding its associated microbiology. Soil was sampled from the roots of Sesuvium verrucosum to obtain the cultivable bacteria. Their morphological characteristics were identified and they were molecularly identified by the 16S sequence. The growth capacity of the bacteria was determined at different levels of pH and salinity, and several growth promotion characteristics were identified, such as phosphorus solubilization, indole acetic acid production by the tryptophan-dependent (AIAt) and tryptophan-independent (IAA) pathways, ammonium production from organic sources, solubilization of carbonates, and zinc and sodium capture capacity. In addition, the bacteria that presented the best characteristics for germination variables of Solanum lycopersicum were evaluated. A total of 20 bacteria from root soil of Sesuvium verrucosum Raf. belonging to the phyla Proteobacteria (50%), Firmicutes (45%) and Actinobacteria (5%) were identified, with each one having different morphological characteristics. Among the bacterial isolates, 45% had the ability to resist different levels of salinity and pH, ranging from 0 to 20% of NaCl, and pH between 5 and 11. Moreover, these bacteria had the capacity to solubilize carbonates, phosphorus and zinc, capture sodium, produce ammonium from organic substrates and IAA (indole acetic acid), and promote enzymatic activity of amylases, proteases, lipases and cellulases. The bacteria evaluated on the germination of Solanum lycopersicum had an influence on germination at different salinity levels, with greater influence at 100 mM NaCl. This demonstrated that halophilic bacteria belonging to the rhizosphere of Sesuvium verrucosum have the ability to promote growth in extreme salinity conditions, making them candidates for the recovery of productivity in saline soils.

Bioaccumulation of PCBs and PBDEs in Fish from a Tropical Lake Chapala, Mexico.

Lake Chapala is the largest natural freshwater reservoir in Mexico and the third largest lake in Latin America. Lakes are often considered the final deposit of polluting materials; they can be concentrated in the organisms that inhabit them, the water, and the sediments. The PCBs and PBDEs are environmental pollutants highly studied for their known carcinogenic and mutagenic effects. PCB and PBDE bioaccumulation levels were determined in Chirostoma spp., Cyprinus carpio, and Oreochromis aureus. In addition, we monitored the concentrations of PCBs and PBDEs in sediment and water from Lake Chapala were monitored. Samples were collected during two periods, in October 2018 and May 2019. The samples were analyzed by gas chromatography coupled with mass spectrometry. Two bioaccumulation factors were determined in fish, one in relation to the concentration of PCBs and PBDEs in sediments and the other in relation to the concentration of PCBs and PBDEs in water. The PCB levels were 0.55-3.29 ng/g dry weight (dw) in sediments, 1.43-2.98 ng/mL in water, 0.30-5.31 ng/g dw in Chirostoma spp., 1.06-6.07 ng/g dw in Cyprinus carpio, and 0.55-7.20 ng/g dw in Oreochromis aureus. The levels of PBDEs were 0.17-0.35 ng/g dw in sediments, 0.13-0.32 ng/mL in water, 0.01-0.23 ng/g dw in Chirostoma spp., 0-0.31 ng/g dw in Cyprinus carpio, and 0.1-0.22 ng/g dw in Oreochromis aureus. This study provides information for a better understanding of the movement, global distribution, and bioaccumulation of PCBs and PBDEs. The results show that the fish, water, and sediments of Lake Chapala are potential risks to the biota and the local human population.

Quantitative Analysis of Rutin by HPTLC and In Vitro Antioxidant and Antibacterial Activities of Phenolic-Rich Extracts from Verbesina sphaerocephala.

Verbesina sphaerocephala A. Gray, like other wild plants of the genus Verbesina, has been used in herbal medicine. There is information for other species of the genus related to their phenolic content, antioxidant capacity, and isolation of bioactive compounds with antimicrobial activity. However, there are no reports for V. sphaerocephala, although it has an important presence in the state of Michoacán, México. In this study, the phenolic composition, quantification of rutin, and in vitro antioxidant and antibacterial activities of methanolic extracts from V. sphaerocephala leaves and flowers were determined. The results showed that all the investigated extracts have high phenolic and flavonoid contents. The flavonoid rutin was identified in all the extracts from V. sphaerocephala by high-performance thin-layer chromatography (HPTLC). The V. sphaerocephala extracts showed scavenging activity against DPPH• and ABTS•+ radicals (IC50 and 5.83 ± 0.50 and 0.93 ± 0.01 mg/mL, respectively) as well as relevant antioxidant capacity (51.05 ± 0.36 mg of ascorbic acid/g of dry tissue). The experimental results show that V. sphaerocephala extracts possessed a strong antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. This research indicates that V. sphaerocephala could be considered as a potential source of natural compounds from the point of ethnopharmacological usage.

Biosaline agriculture: an agronomic proposal for onion (Allium cepa L.) production.

NOVELTY STATEMENT: The onion crop with brackish irrigation but accompanied by halophytes is productive, so halophytoremediation is an excellent agronomic proposal for areas where there is poor quality water used for irrigation.

Potential of Bacopa monnieri (L.) Wettst and Sesuvium verrucosum Raf. as an agronomic management alternative to recover the productivity of saline soils.

Water scarcity and increasing salinity are the main limiting environmental factors directly affecting the establishment and development of agroecosystems. The objective of this study was to assess the capacity of the halophytes Bacopa monnieri (L.) Wettst and Sesuvium verrucosum Raf., to improve the chemical properties of a saline soil during a 240-day period in the field so as to subsequently examine their potential to associate with Zea mays in the previously desalinated surface. The treatments proposed were [T1 (reference soil sample), T2 (soil + B. monnieri), T3 (soil + S. verrucosum), and T4 (soil + B. monnieri + S. verrucosum)]. The results showed that the association of the species B monnieri and S. verrucosum has the potential to enhance the chemical characteristics of the severely saline and clayey soil, showing ECe reductions of 11.13-7.97 dS/m and pH of 7.84-7.42, as well as increase in soil porosity from 54.71% to 57.23%. It was also found that the association of these plants have a phytodesalination capacity of 1.21 t Na+ ha-1, this served to prepare the conditions for the growth of the Z. mays and generate yields of 8.5 t ha-1.

Phenolic Profile, Antioxidant and Anti-Proliferative Activities of Methanolic Extracts from Asclepias linaria Cav. Leaves.

Asclepias linaria Cav. (Apocynaceae) is a shrubby plant endemic of Mexico which has been used in traditional medicine. However, the bioactive potential of this plant remains unexplored. In this study, the phenolic composition, antioxidant, and cytotoxic activities of A. linaria leaves were determined. In order to estimate the phenolic composition of the leaves, the total phenolic, flavonoid, and condensed tannins contents were determined. Furthermore, the antioxidant activity was measured by the scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2'-azino-bis[3-ethylbenzothiazoline-6-sulphonic acid] (ABTS•+) radicals and the total antioxidant capacity. The phenolic compounds identified in the A. linaria leaves by ultra-performance liquid chromatography coupled to mass spectrometry (UPLC-MS) include phenolic acids, such as p-coumaric and ferulic acid, as well as flavonoids, such as rutin and quercetin. The leaves' extracts of A. linaria showed a high scavenging activity of DPPH• and ABTS•+ radicals (IC50 0.12 ± 0.001 and 0.51 ± 0.003 µg/mL, respectively), high total antioxidant capacity values (99.77 ± 4.32 mg of ascorbic acid equivalents/g of dry tissue), and had a cytotoxic effect against K562 and HL60 hematologic neoplasia cells lines, but no toxicity towards the normal mononuclear cell line was observed. These results highlight the potential of A. linaria and could be considered as a possible alternative source of anticancer compounds.

Scenarios of availability of water due to overexploitation of the aquifer in the basin of Laguna de Santiaguillo, Durango, Mexico.

BACKGROUND: The importance of water to life is unquestionable. Most of the fresh water we use for daily activities comes from the aquifers, which in many cases due to misuse are overexploited and at risk. This article studies the aquifer that appeared in Laguna de Santiaguillo basin; it should be noted that the most important economic activity in the basin is agriculture. METHODS: By analyzing vector and demographic information, using GIS and with some field trips, the impact and risk on the level of disposition in every micro-basin that forms the basin were determined. RESULTS: The different modeling scenarios demonstrate that the basin and sub-basins that conform Santiaguillo are overexploited. DISCUSSION: The volumes concessioned are of such magnitude that they generate a condition of vulnerability to the activities of the basin and sustain the overexploitation conditions of the aquifer.

Tracking Metal Pollution in Lake Chapala: Concentrations in Water, Sediments, and Fish.

We measured concentrations of selected metals (Al, Ba, Cu, Mn, Hg, Sr, V, and Zn) in water, sediments, and fish from Lake Chapala and a reference site to evaluate potential negative effects on wildlife, particularly fish-eating birds. Fish metal concentrations ranged from 0.05 µg/g wet weight (ww) for Al and Cu to 64.70 µg/g ww for Sr. There was a positive and significant correlation between fish length and metals particularly for Ba, Cu, Mn, and Zn in Lake Chapala (p < 0.05). However, there were no significant correlations between metal concentrations and δ(15)N values in fish indicating no biomagnification through the food web. Overall, metal concentrations in water, sediments, and fish were similar to and in some cases below those reported for Lake Chapala over the last 20 years. Also, metal concentrations were below those that could be of concern for negative effects on fish and wildlife of Lake Chapala.

Accumulation and hazard assessment of mercury to waterbirds at Lake Chapala, Mexico.

Lake Chapala is the largest tropical lake in Mexico. The objectives of this study were to determine bioaccumulation of Hg in fish and to evaluate the potential impacts of Hg in the diet of aquatic birds, particularly the American white pelican (AWPE), in Lake Chapala. Hg concentrations in three fish species ranged from 0.021 to 0.568 µg/g wet weight. Mercury in fish was positively and significantly correlated with total fish length (R2=0.44, P<0.05). The δ15N values in fish were significantly correlated with Hg concentrations in Chapala and the San Antonio Reservoir (R2=0.69, P<0.001 and R2=0.40, P<0.001, respectively). However, Hg concentrations in bird feathers were not significantly different between years, among locations, or among species. Hg concentrations in fish from Lake Chapala were within values reported in many parts of the world. The Hg (mean range of 2.75 to 4.54 µg/g dw) and δD (mean range of -62‰ to -11‰) values in bird feathers suggested a wide pattern of exposure for highly migratory AWPE and egrets, although birds with lower δD values in feathers appeared to have greater concentrations of Hg than those with higher δD values. Contaminant exposure in aquatic birds in Chapala during the breeding season should be monitored next to better determine the potential effects of Hg on resident aquatic birds.

Eisenia fetida increased removal of polycyclic aromatic hydrocarbons from soil.

The removal of phenanthrene, anthracene and benzo(a)pyrene added at three different concentrations was investigated with or without earthworms (Eisenia fetida) within 11 weeks. Average anthracene removal by the autochthonous micro-organisms was 23%, 77% for phenanthrene and 13% for benzo(a)pyrene, while it was 51% for anthracene, 47% for benzo(a)pyrene and 100% for phenanthrene in soil with earthworms. At 50 and 100mg phenanthrene kg(-1)E. fetida survival was 91% and 83%, but at 150 mg kg(-1) all died within 15 days. Survival of E. fetida in soil amended with anthracene < or = 1000 mg kg(-1) and benzo(a)pyrene < or = 150 mg kg(-1) was higher than 80% and without weight loss compared to the untreated soil. Only small amounts of PAHs were detected in the earthworms. It was concluded that E. fetida has the potential to remove large amounts of PAHs from soil, but more work is necessary to elucidate the mechanisms involved.