Description: The aim of the present study was to evaluate abiotic stress tolerance of rhizobial strains belonging to Mesorhizobium , Sinorhizobium , and Rhizobium genera, as well as to investigate specie specific stress response mechanisms. Effect of NaCl and PEG on growth capacity, protein, lipid peroxydation (MDA), membrane fatty acid composition and antioxidant enzymes were investigated. Growth capacity and viability of overall rhizobia strains decreased proportionally to the increase of NaCl and PEG levels in the medium. Sinorhizobium strains appeared the most tolerant, where 4H41strain was able to grow at 800 mM NaCl and 40% PEG. On the other hand, growth of R. gallicum and M. mediterraneum was inhibited by 200 mM NaCl. The content of MDA was unchanged in Sinorhizobium strains under both stresses. For Mesorhizobium , only PEG treatment increased the content of MDA. Amount of the C19:0 cyclo fatty-acid was increased in both Sinorhizobium and Mesorhizobium tolerant strains. NaCl stress increased Superoxide dismutase (SOD) activity of overall species; especially the most tolerant strain 4H41. Both treatments increased catalase (CAT) activity in 4H41, TII7, and 835 strains. Obtained results suggest that major response of tolerant Sinorhizobium and Mesorhizobium strains to NaCl and PEG stresses is a preferential accumulation of the C19:0 cyclo fatty acid within bacterial membrane as mechanism to reduce fluidity and maintain integrity. Cell integrity and functioning is also assured by maintaining and/or increasing activity of SOD and CAT antioxidant enzymes for tolerant strains to omit structural and functional damages related to reactive oxygen species overproduced under stressful conditions.

Description: A novel co-enrichment technique was designed for enrichment of magnetotactic bacteria from soil, water, and sediments. Delayed addition of iron uptake inducer and the iron source proved amenable to induce magnetosome synthesis by MTB followed by their separation from consortium using magnetic flux. We successfully enriched and isolated both North seeking as well as South seeking magnetotactic bacteria from Lonar Lake (Buldhana), Moti Lake (Jalna), Ghanewadi Lake (Jalna), Ganesh Lake (Miraj), Rankala Lake (Kolhapur), and industrial metal-contaminated glaying soils (Jalna) and a soil (Karad), (MS, India) exposed to high-voltage electric current. The hanging drop preparations and growth under magnetic stress on low-agar media allowed conformation of magnetotactic behavior of the isolates. Both Gram positive and Gram negative MTB were isolated with diverse morphologies. South seeking population was more predominant. The soil inhabitants showed little dwelling property which was more prominent in case of aquatic inhabitants. The use of in situ pH and salt concentrations during enrichment and isolation found suited. The simultaneous growth of whole consortium in the system ensured the in situ simulation of microenvironment needful for proper growth of fastidious MTB.

Description: The Anoxybacillus sp. SK 3–4, previously isolated from a hot spring, was screened for its heavy metals resistance (Al 3+ , Mn 2+ , Cu 2+ , Co 2+ , Zn 2+ , and Ni 2+ ) and the strain was found to be most resistant to aluminum. Significant growth of the strain was observed when it was grown in medium containing aluminum (200 mg L −1 –800 mg L −1 ) with relative growth rates ranging between 77% and 100%. A gene encoding the aluminum resistance protein (accession number: WP_021095658.1) was found in genome of strain SK 3–4, which revealed high sequence identity (〉95%) to its homologues from Anoxybacillus species. Sequence comparisons with two functionally characterized aluminum resistance proteins, namely G2alt and ALU1-P, showed 97% and 81% of sequence identity, respectively. Four putative metal binding sites were detected in SK 3–4 aluminum resistance protein and G2alt at same amino acid residue positions of 186, 195, 198, and 201. Strain SK 3–4 was found to be able to remove aluminum from aqueous solution. This study demonstrated that Anoxybacillus sp. SK 3–4 could be applied in the treatment of aluminum contaminated wastewater.

Description: Bacterial populations in the phylloplane of four different Prunus species were investigated by 16 S rRNA pyrosequencing. Bioinformatic analysis identified an average of 510 operational taxonomic units belonging to 159 genera in 76 families. The two genera, Sphingomonas and Methylobacterium, were dominant in the phylloplane of four Prunus species. Twenty three genera were commonly identified in the four Prunus species, indicating a high level of bacterial diversity dependent on the plant species. Our study based on 16 S rRNA sequencing reveals the complexity of bacterial diversity in the phylloplane of Prunus species in detail.

Description: The classic plaque assay is a method for counting infectious viral particles, however its complexity limits its use in a variety of virological experiments. To simplify the operation and to improve the repeatability, we employed an improved plaque assay procedure based on Avicel to make the whole experiment easier and optimize the results on a model of Vero cells infection with Enterovirus 71(EV71). Clear plaques visible to the naked eyes can be formed on a 24-well plate or a 96-well plate without immunostaining. Following further improvement, this plaque assay procedure could be applied to other viruses, being both simple and repeatable.

Description: Cyanobacteria-rice plant interactions were analyzed using a hydroponics experiment. The activity of plant defense and pathogenesis-related enzymes, scanning electron microscopy, growth, nitrogen fixation (measured as ARA), and DNA fingerprinting assays proved useful in illustrating the nature of associations of cyanobacteria with rice plants. Microscopic analyses revealed the presence of short filaments and coiled masses of filaments of cyanobacteria near the epidermis and cortex of roots and shoot tissues. Among the six cyanobacterial strains employed, Calothrix sp. (RPC1), Anabaena laxa (RPAN8), and Anabaena azollae (C16) were the best performing strains, in terms of colonization in roots and stem. These strains also enhanced nitrogen fixation and stimulated the activity of plant defense/cell wall-degrading enzymes. A significantly high correlation was also recorded between the elicited plant enzymes, growth, and ARA. DNA fingerprinting using highly iterated palindromic sequences (HIP-TG) further helped in proving the establishment of inoculated organisms in the roots/shoots of rice plants. This study illustrated that the colonization of cyanobacteria in the plant tissues is facilitated by increased elicitation of plant enzymes, leading to improved plant growth, nutrient mobilization, and enhanced plant fitness. Such strains can be promising candidates for developing “cyanobacteria colonized-nitrogen-fixing rice plants” in the future.

Description: In vitro mycorrhization between Scleroderma laeve and Eucalyptus grandis . At 15 days of association, fungal hyphae form the mantle, and the epidermal cells are more elongated. In this stage, the fungal hyphae covered the primary root and began to grow between the enlarged epidermal cells. The formation of the Hartig net was noted in this stage of contact, and it continued to develop over a 30-day period. (Photo: Maíra de Freitas Pereira, Viçosa-Minas Gerais (MG), Brazil)

Description: In this study, a highly effective chlorpyrifos (CP)-degrading bacterium (termed strain X1) was isolated from the sludge of drain outlet of a chlorpyrifos manufacturer. Strain X1 was identified as Cupriavidus taiwanensis based upon the analysis of the 16S rDNA gene and biochemical characteristics, which is capable of transforming CP into 3,5,6-trichloro-2-pyridinol (TCP), and the resulting TCP was further metabolized when performed in an aqueous medium. Degradation experiments were carried out under different conditions at the range of pH (5.0∼9.0) and temperature (22∼42 °C), and the optimized pH and temperature were 7.0 and 32 °C respectively. Biotransformation of high concentration of CP was also determined; 400 mg l −1 of CP was completely transformed within 36 h; approximately 95% of CP was removed within 48 h when concentration of CP was up to 500 mg l −1 . A genomic library was successfully constructed to clone the gene encoding the CP hydrolase, and a positive transformant with clear hydrolytic zones was obtained and analyzed. The insert gene sequence exhibited close relationship with 99% similar to opdB gene encoding parathion hydrolase, whereas, transformant failed in degrading the accumulated TCP. These results highlight the potential of this bacterium to be used in the cleanup of CP.

Description: The simultaneous removal of sulfide and p -cresol was carried out by using a marine-denitrifying consortium collected in the coastal zone of Sonora, Mexico. Different experimental conditions were used to evaluate the capacity of the consortium to simultaneously eliminate nitrate, sulfide, and p -cresol. For instance, the first set of assays was conducted at different sulfide concentrations (20, 50, and 100 mg S 2− L −1 ), with a fixed concentration of p -cresol (45 mg C L −1 ). The second set of assays was developed at different concentrations of p -cresol (45, 75, and 100 mg C L −1 ), in the presence of 20 mg S 2− L −1 . In all cases, the concentration of nitrate was stoichiometrically added for the complete oxidization of the substrates. The results showed removal efficiencies up to 92% for p -cresol and nitrate at 20 and 50 mg S 2− L −1 ; whereas at 100 mg S 2− L −1 removal efficiencies were 77% and 59% for p -cresol and nitrate, respectively. On the other hand, sulfide (20 mg L −1 ) was completely removed under different concentrations of p -cresol tested, with a partial accumulation of nitrite according to the increment of p -cresol concentration. The results obtained indicate that the marine consortium was able to simultaneously remove the pollutants studied.