Heavy metal pollution is a severe concern worldwide, owing to its harmful effects on ecosystems. Phytoremediation has been applied to remove heavy metals from water, soils, and sediments by using plants and associated microorganisms to restore contaminated sites. The Typha genus is one of the most important genera used in phytoremediation strategies because of its rapid growth rate, high biomass production, and the accumulation of heavy metals in its roots. Plant growth-promoting rhizobacteria have attracted much attention because they exert biochemical activities that improve plant growth, tolerance, and the accumulation of heavy metals in plant tissues. Because of their beneficial effects on plants, some studies have identified bacterial communities associated with the roots of Typha species growing in the presence of heavy metals. This review describes in detail the phytoremediation process and highlights the application of Typha species. Then, it describes bacterial communities associated with roots of Typha growing in natural ecosystems and wetlands contaminated with heavy metals. Data indicated that bacteria from the phylum Proteobacteria are the primary colonizers of the rhizosphere and root-endosphere of Typha species growing in contaminated and non-contaminated environments. Proteobacteria include bacteria that can grow in different environments due to their ability to use various carbon sources. Some bacterial species exert biochemical activities that contribute to plant growth and tolerance to heavy metals and enhance phytoremediation.

Plant-associated bacteria in heavy-metal-contaminated environments could be a biotechnological tool to improve plant growth. The present work aimed to isolate lead- and cadmium-tolerant endophytic bacteria from the roots of Typha latifolia growing in a site contaminated with these heavy metals. Endophytic bacteria were characterized according to Pb and Cd tolerance, plant-growth-promoting rhizobacteria activities, and their effect on T. latifolia seedlings exposed and non-exposed to Pb and Cd. Pb-tolerant isolates were identified as Pseudomonas azotoformans JEP3, P. fluorescens JEP8, and P. gessardii JEP33, while Cd-tolerant bacteria were identified as P. veronii JEC8, JEC9, and JEC11. They all exert biochemical activities, including indole acetic acid synthesis, siderophore production, and phosphate solubilization. Plant–bacteria interaction assays showed that P. azotoformans JEP3, P. fluorescens JEP8, P. gessardii JEP33, and P. veronii JEC8, JEC9, JEC11 promote the growth of T. latifolia seedlings by increasing the root and shoot length, while in plants exposed to either 5 mg/L of Pb or 10 mg/L of Cd, all bacterial isolates increased the shoot length and the number of roots per plant, suggesting that they are plant-growth-promoting rhizobacteria that could contribute to T. latifolia adaptation to the heavy metal polluted site.

The Typha genus comprises plant species extensively studied for phytoremediation processes. Recently, Pseudomonas rhodesiae GRC140, an IAA-producing bacterium, was isolated from Typha latifolia roots. This bacterium stimulates the emergence of lateral roots of Arabidopsis thaliana in the presence and absence of cadmium. However, the bacterial influence on cadmium accumulation by the plant has not been determined. Moreover, the P. rhodesiae GRC140 effect in Cd phytoextraction by T. latifolia remains poorly understood. In this work, an axenic hydroponic culture of T. latifolia was established. The plants were used to evaluate the effects of cadmium stress in axenic plants and determine the effects of P. rhodesiae GRC140 and exogenous indole acetic acid (IAA) on Cd tolerance and Cd uptake by T. latifolia. Biomass production, total chlorophyll content, root electrolyte leakage, catalase activity, total glutathione, and Cd content were determined. The results showed that Cd reduces shoot biomass and increases total glutathione and Cd content in a dose-dependent manner in root tissues. Furthermore, P. rhodesiae GRC140 increased Cd translocation to the shoots, while IAA increased the Cd accumulation in plant roots, indicating that both treatments increase Cd removal by T. latifolia plants. These results indicate that axenic plants in hydroponic systems are adequate to evaluate the Cd effects in plants and suggest that T. latifolia phytoextraction abilities could be improved by P. rhodesiae GRC140 and exogenous IAA application.

Mansoa hymenaea (DC.) A.H. Gentry is used in traditional medicine to treat pain, arthritis, and rheumatoid disease. It has also been demonstrated that species belonging to the Mansoa genus exert cytotoxic activity. Despite this data, biological properties and phytochemistry of M. hymenaea remain poorly understood. Therefore, we determined the metabolite profile of the methanolic extract of M. hymenaea leaves and evaluated its anti-inflammatory, antinociceptive, and cytotoxic activity. Phytochemical analysis was carried out by conventional methods and gas chromatography-mass spectrometry. Anti-inflammatory and antinociceptive effects were assessed in the TPA‑induced ear edema model and acetic acid-induced writhing test, respectively. Cytotoxic activity was determined in vitro against SW-620, MDA-MB231, SiHa, SKLU1, and PC-3 cancer cell lines. The results revealed that M. hymenaea methanolic extract at 2 mg/ear reduced inflammation significantly (p ≤ 0.05) by 50.4 ± 5.9 %, and decreased visceral pain with an effective dose 50 (ED₅₀) of 148.9 ± 14.1 mg kg⁻¹. Moreover, M. hymenaea exerted cytotoxic activity against the breast carcinoma cell line (MDA-MB231) with IC₅₀ = 125.8 ± 16.7 µg mL⁻¹. Chemical analyses revealed that M. hymenaea methanolic extract contained alkaloids, glycosides, tannins, sterols, and saponins. Likewise, trans-13-octadecenoic acid, n-hexadecanoic acid, diallyl disulfide, diallyl trisulfide, β-sitosterol, methyl ursolate, stigmasterol, and phytol were detected by CG-MS in the M. hymenaea methanolic extract. These compounds were previously reported with anti-inflammatory, antinociceptive, or cytotoxic effects. Therefore, the methanolic extract of M. hymenaea leaves is a good source of natural compounds with anti-inflammatory, antinociceptive, and cytotoxic properties.