Effectiveness of the toxin-degrading strain screening strategy: Deficiency and improvement in screening the gossypol-degrading microorganism Aspergillus niger

The effectiveness of the classic screening strategy was verified, by duplicating and verifying the degradation of gossypol by the Aspergillus niger. It can reduce the free gossypol content through biosorption but has no effect on the total gossypol content and cannot effectively degrade gossypol. And the most interesting thing we found the strain can secrete agarase, utilise agar as carbon source. In this case, that will mislead researchers and lead them to make wrong judgments. That turns out the usual methods of previous screening strategies are not rigorous enough, the classic screening method has defect in screening toxin-degrading strain, so agar control group should be added. In this study, some suggestions are put forward to optimise the same type of experiments and broaden the idea of detoxification by microorganisms and provide reference for screening effective toxin-degrading microorganisms.

Molecular and phylogenic identifications of potential herbicide degrading microorganisms from contaminated farmland in Keffi, Nasarawa State, Nigeria

Background: Over the past years, the continuous use of herbicides has raised increasing concern mainly due to their massive pollution of the environment. To address this problem, the herbicide-degrading microorganism might be very promising. Method: In the present study, a total of twenty (20) soil samples were collected, bacteria and fungi were isolated from the soil and identified using standard microbiological and molecular studies. Results: The results revealed that a total of 2 bacterial (Enterobacter asburiae and Pseudomonas aeruginosa) and 2 fungi (Aspergillus flavus and Fusarium redolens) strains were isolated from the soil samples collected from herbicide contaminated soil in Keffi, Nasarawa State, Nigeria. The E. asburiae and P. aeruginosa had 75.0%, and 100% occurrence while the fungi isolates including the A. flavus and F. redolens had 75.0%, and 100% occurrence respectively. The 16S rDNA and ITS1F analysis confirmed the identity of the bacteria and fungi genus. Phylogenetic analysis suggested the bacteria strains were closely related to Pseudomonas aeruginosa strain CIFRI DTSB1 and Enterobacter sp revealed a close relatedness with Enterobacter asburiae RD-DAROS-04 strain, whereas, the fungi strain revealed a closely relatedness of Fusarium redolens strainTIST190421511. Conclusion: In conclusion, the microbial strains including Pseudomonas aeruginosa strain CIFRI DTSB1, Entrobacter asburiae RD-DAROS-04, and Fusarium redolens strainTIST190421511 were the major microbial habitant of pesticide-contaminated farmland in Keffi, and thus represent the herbicide degrading microorganism in this region. Further studies on the herbicide degrading properties of these microbial strains are underway.

A Seed Mucilage-Degrading Fungus From the Rhizosphere Strengthens the Plant-Soil-Microbe Continuum and Potentially Regulates Root Nutrients of a Cold Desert Shrub

Seed mucilage plays important roles in the adaptation of desert plants to the stressful environment. Artemisia sphaerocephala is an important pioneer plant in the Central Asian cold desert, and it produces a large quantity of seed mucilage. Seed mucilage of A. sphaerocephala can be degraded by soil microbes, but it is unknown which microorganisms can degrade mucilage or how the mucilage-degrading microorganisms affect rhizosphere microbial communities or root nutrients. Here, mucilage-degrading microorganisms were isolated from the rhizosphere of A. sphaerocephala, were screened by incubation with mucilage stained with Congo red, and were identified by sequencing and phylogenetic analyses. Fungal-bacterial networks based on high-throughput sequencing of rhizosphere microbes were constructed to explore the seasonal dynamic of interactions between a mucilage-degrading microorganism and its closely related microorganisms. The structural equation model was used to analyze effects of the mucilage-degrading microorganism, rhizosphere fungal-bacterial communities, and soil physicochemical properties on root C and N. The fungus Phanerochaete chrysosporium was identified as a mucilage-degrading microorganism. Relative abundance of the mucilage-degrading fungus (MDF) was highest in May. Subnetworks showed that the abundance of fungi and bacteria closely related to the MDF also were highest in May. Interactions between the MDF and related fungi and bacteria were positive, which might enhance mucilage degradation. In addition, the MDF might regulate root C and N by affecting rhizosphere microbial community structure. Our results suggest that MDF from the rhizosphere strengthens the plant-soil-microbe continuum, thereby potentially regulating microbial interactions and root nutrients of A. sphaerocephala. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

The presence of cellulose-degrading microorganisms in Perisesarma eumolpe crab’s stomach at opened areas of Can Gio mangrove forest

The study was conducted to determine the presence of cellulose-degrading microorganisms which were living in the stomach of Perisesarma eumolpe crabs. P. eumolpe were collected in the gap of Can Gio mangrove caused by Durian typhoon in 2006. The study identified 520 microorganism samples from 30 stomach samples Cellulose degrading microbacteria were isolated on three types of nutrient media: meat extract – peptone, Gause and Czapek – Dok with CMC. These 520 microbial samples included of 496 aerobic bacteria, 7 actinomycetes and 0 mold samples. The number of cellulose degrading microorganisms was also accounted for 46% of total (240 samples). Among these, there were 24 bacteria strains and 5 actinomycetes strains which degradated cellulose based on the difference in the colony and the cell shape. The average microbial density per crab gut was approximately 0.66 ×105 to 6.6 ×105 cell/mL. In addition, the results showed that cellulose degrading microorganism groups have importantly contributed to the food sources for P. eumolpe during their living in the mangrove forest.

Heptachlor degradation characteristics of a novel strain and its application

With heptachlor as the sole carbon source, an effective heptachlor-degrading microorganism (named strain H) was isolated from the sludge of heptachlor-polluted sewage of a chemical plant, via enrichment, screening and purification. Strain H was identified as a facultative anaerobic Gram-negative bacterial strain belonging to genus Shigella based on the physiological-biochemical characteristics and the similarity analysis of its 16S rDNA gene sequence with the sequences logged in the Ribosomal Database Project and GenBank databases. When the optimal inoculation volume and the pH were 20% and 7.1–7.6, respectively, strain H was able to degrade heptachlor by more than 88.2% after130 h, with initial concentration of heptachlor being 300 μg/L at 30 ± 0.5 °C. It was also shown that strain H can grow on the degradation products of heptachlor such as 1-hydroxychlordene or heptachlor epoxide. Furthermore, additional carbon sources can accelerate the degradation rate of heptachlor because of co-metabolism. The degradation dynamics could be described by a first-order reaction model. A real-world field experiment demonstrated that strain H was effective in practical applications of heptachlor biodegradation in contaminated soil.