Arsenic and Microorganisms: Genes, Molecular Mechanisms, and Recent Advances in Microbial Arsenic Bioremediation.

Throughout history, cases of arsenic poisoning have been reported worldwide, and the highly toxic effects of arsenic to humans, plants, and animals are well documented. Continued anthropogenic activities related to arsenic contamination in soil and water, as well as its persistency and lethality, have allowed arsenic to remain a pollutant of high interest and concern. Constant scrutiny has eventually resulted in new and better techniques to mitigate it. Among these, microbial remediation has emerged as one of the most important due to its reliability, safety, and sustainability. Over the years, numerous microorganisms have been successfully shown to remove arsenic from various environmental matrices. This review provides an overview of the interactions between microorganisms and arsenic, the different mechanisms utilized by microorganisms to detoxify arsenic, as well as current trends in the field of microbial-based bioremediation of arsenic. While the potential of microbial bioremediation of arsenic is notable, further studies focusing on the field-scale applicability of this technology is warranted.

Biotechnology-based microbial degradation of plastic additives.

Plastic additives are agents responsible to the flame resistance, durability, microbial resistance, and flexibility of plastic products. High demand for production and use of plastic additives is associated with environmental accumulation and various health hazards. One of the suitable methods of depleting plastic additive in the environment is bioremediation as it offers cost-efficiency, convenience, and sustainability. Microbial activity is one of the effective ways of detoxifying various compounds as microorganisms can adapt in an environment with high prevalence of pollutants. The present review discusses the use and abundance of these plastic additives, their health-related risks, the microorganisms capable of degrading them, the proposed mechanism of biodegradation, and current innovations capable of improving the efficiency of bioremediation.

Antibacterial and COX-2 Inhibitory Tetrahydrobisbenzylisoquinoline Alkaloids from the Philippine Medicinal Plant Phaeanthus ophthalmicus.

Phaeanthus ophthalmicus (Roxb. ex G.Don) J.Sinclair (previously known as P. ebracteolatus (Presl) Merr) is a Philippine medicinal plant occurring as evergreen shrub in the lowland forests of Luzon islands. It is used traditionally by Filipinos to treat bacterial conjunctivitis, ulcer and wound infections. Based on previous investigations where cyclooxygenase-2 (COX-2) functions as immune-linked factor in infectious sensitivities to bacterial pathogens by triggering pro-inflammatory immune-associated reactions, we investigated the antimicrobial and COX inhibitory activities of the extracts and tetrahydrobisbenzylisoquinoline alkaloids of P. ophthalmicus in vitro and in silico to validate its ethnomedicinal uses. Thus, the dichloromethane-methanol (DCM-MeOH) crude extract and alkaloid extracts exhibiting antibacterial activities against drug-resistant bacterial strains such as methicillin-resistance Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Klebsiella pneumoniae + CRE and Pseudomonas aeruginosa + MBL afforded (+)-tetrandrine (1) and (+)-limacusine (2) as the major biologically active tetrahydrobisbenzylisoquinoline alkaloidal constituents after purification. Both tetrahydrobisbenzylisoquinoline alkaloids 1 and 2 showed broad spectrum antibacterial activity with strongest inhibition against the Gram-negative bacteria MßL-Pseudomonas aeruginosa Klebsiella pneumoniae + CRE. Interestingly, the alkaloid limacusine (2) showed selective inhibition against ovine COX-2 in vitro. These results were ascertained by molecular docking and molecular dynamics simulation experiments where alkaloid 2 showed strong affinity in the catalytic sites of Gram-negative bacterial enzymes P. aeruginosa elastase and K. pneumoniae KPC-2 carbapenemase (enzymes involved in infectivity mechanisms), and of ovine COX-2. Overall, our study provides credence on the ethnomedicinal use of the Philippine medicinal plant P. ophthalmicus as traditional plant-based adjuvant to treat bacterial conjunctivitis and other related infections. The antibacterial activities and selective COX-2 inhibition observed for limacusine (2) point to its role as the biologically active constituent of P. ophthalmicus. A limited number of drugs with COX-2 inhibitory properties like celecoxib also confer antibacterial activity. Thus, tetrahydrobisbenzyl alkaloids, especially 2, are promising pharmaceutical inspirations for developing treatments of bacterial/inflammation-related infections.

Biodiscovery of antibacterial constituents from the endolichenic fungi isolated from Parmotrema rampoddense.

A total of nine endolichenic fungi were isolated from the foliose lichen Parmotrema rampoddense (Nyl.) Hale. Of the nine endolichenic fungi, three taxa (Fusarium proliferatum, Nemania primolutea, Daldinia eschsholtzii) showed antibacterial activities as determined by the disk diffusion assay against ESKAPE bacterial pathogens. Fusarium proliferatum gave the most active fungal extract with zone of inhibition values of 15 mm and 19 mm against E. faecalis and S. aureus, respectively. Further chromatographic purification of the F. proliferatum ethyl acetate extract led to the isolation and identification of bis(2-ethylhexyl)terephthalate (1), acetyl tributyl citrate (2), and fusarubin (3). Acetyl tributyl citrate (2) exhibited moderate antibacterial activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus.