Application of ultraviolet-visible spectroscopy coupled with support vector regression for the quantitative detection of thiamethoxam in tea.

A model combining UV-visible (UV-Vis) spectroscopy and support vector regression (SVR) for the quantitative detection of thiamethoxam in tea is proposed. First, each original UV-Vis spectrum in the sample set is decomposed into some intrinsic mode functions (IMFs) and a residual via ensemble empirical mode decomposition. Next, the decomposed IMFs are reconstructed into high-frequency and low-frequency matrices, and the residuals are combined into a trend matrix. Then, the SVR is used to build regression sub-models between each matrix and the content of thiamethoxam in tea. Finally, the combination model is established by a weighted average of the sub-models. The prediction results are compared with SVR and SVR coupled with several preprocessing methods, and the results demonstrate the superiority of the proposed approach in the quantitative detection of thiamethoxam in tea.

Bacterial adaptive strategies to cope with metal toxicity in the contaminated environment - A review.

Heavy metal contamination poses a serious environmental hazard, globally necessitating intricate attention. Heavy metals can cause deleterious health hazards to humans and other living organisms even at low concentrations. Environmental biotechnologists and eco-toxicologists have rigorously assessed a plethora of bioremediation mechanisms that can hamper the toxic outcomes and the molecular basis for rejuvenating the hazardous impacts, optimistically. Environmental impact assessment and restoration of native and positive scenario has compelled biological management in ensuring safety replenishment in polluted realms often hindered by heavy metal toxicity. Copious treatment modalities have been corroborated to mitigate the detrimental effects to remove heavy metals from polluted sites. In particular, Biological-based treatment methods are of great attention in the metal removal sector due to their high efficiency at low metal concentrations, ecofriendly nature, and cost-effectiveness. Due to rapid multiplication and growth rates, bacteria having metal resistance are advocated for metal removal applications. Evolutionary implications of coping with heavy metals toxicity have redressed bacterial adaptive/resistance strategies related to physiological and cross-protective mechanisms. Ample reviews have been reported for the bacterial adaptive strategies to cope with heavy metal toxicity. Nevertheless, a holistic review summarizing the redox reactions that address the cross-reactivity mechanisms between metallothionein synthesis, extracellular polysaccharides production, siderophore production, and efflux systems of metal resistant bacteria are scarce. Molecular dissection of how bacteria adapt themselves to metal toxicity can augment novel and innovative technologies for efficient detoxification, removal, and combat the restorative difficulties for stress alleviations. The present comprehensive compilation addresses the identification of newer methodologies, summarizing the prevailing strategies of adaptive/resistance mechanisms in bacterial bioremediation. Further pitfalls and respective future directions are enumerated in invigorating effective bioremediation technologies including overexpression studies and delivery systems. The analysis will aid in abridging the gap for limitations in heavy metal removal strategies and necessary cross-talk in elucidating the complex cascade of events in better bioremediation protocols.

Root Endophytes and Ginkgo biloba Are Likely to Share and Compensate Secondary Metabolic Processes, and Potentially Exchange Genetic Information by LTR-RTs.

Ginkgo biloba is a pharmaceutical resource for terpenes and flavonoids. However, few insights discussed endophytes' role in Ginkgo, and whether genetic exchange happens between Ginkgo and endophytes remains unclear. Herein, functional gene profiles and repetitive sequences were analyzed to focus on these issues. A total of 25 endophyte strains were isolated from the Ginkgo root and distributed in 16 genera of 6 phyla. Significant morphological diversities lead to the diversity in the COG functional classification. KEGG mapping revealed that endophytic bacteria and fungi potentially synthesize chalcone, while endophytic fungi might also promote flavonoid derivatization. Both bacteria and fungi may facilitate the lignin synthesis. Aspergillus sp. Gbtc_1 exhibited the feasibility of regulating alcohols to lignans. Although Ginkgo and the endophytes have not observed the critical levopimaradiene synthase in ginkgolides synthesis, the upstream pathways of terpenoid precursors are likely intact. The MVK genes in Ginkgo may have alternative non-homologous copies or be compensated by endophytes in long-term symbiosis. Cellulomonas sp. Gbtc_1 became the only bacteria to harbor both MEP and MVA pathways. Endophytes may perform the mutual transformation of IPP and DMAPP in the root. Ginkgo and bacteria may lead to the synthesis and derivatization of the carotenoid pathway. The isoquinoline alkaloid biosynthesis seemed lost in the Ginkgo root community, but L-dopa is more probably converted into dopamine as an essential signal-transduction substance. So, endophytes may participate in the secondary metabolism of the Ginkgo in a shared or complementary manner. Moreover, a few endophytic sequences predicted as Ty3/Gypsy and Ty1/Copia superfamilies exhibited extremely high similarity to those of Ginkgo. CDSs in such endophytic LTR-RT sequences were also highly homologous to one Ginkgo CDS. Therefore, LTR-RTs may be a rare unit flowing between the Ginkgo host and endophytes to exchange genetic information. Collectively, this research effectively expanded the insight on the symbiotic relationship between the Ginkgo host and the endophytes in the root.

Traits of Exogenous Species and Indigenous Community Contribute to the Species Colonization and Community Succession.

Introducing exogenous species into an environment is an effective method to strengthen ecological functions. The traits of the exogenous species and the indigenous communities, as well as the resistance and subsequent succession of the community to exogenous species, are not well-understood. Here, three different functional consortia were introduced into two extremely acidic systems, leaching heap (LH) and leaching solution (LS), derived from the Zijin copper mine in China. The results showed that the structures of both LS and LH communities were affected by the three consortia, but not all the structural changes were in line with variations of community function. Among the three consortia, only the complementary sulfur oxidizers greatly enhanced copper extraction efficiency of LS (by 50.42%). This demonstrated that functional niche novelty gave exogenous species an advantage to occupy an ecological niche in a complementary manner, thus leading to successful colonization. The resistance to, and subsequent succession by, exogenous organisms varied between the two indigenous communities. More specifically, the LS community with low community diversity and simple composition was susceptible to exogenous species, and the community structural changes of LS were both divergent and irreversible. In comparison, the LH community with greater community diversity and more complex composition was more resistant to exogenous species, with the community structures showing a convergent trend over time despite different species being introduced. Therefore, we propose that diverse communities compete for resources more intensely with exogenous species and resist their introduction, and that communities with complex composition are able to cope with exogenous disturbances.