Adaptive Strategies of Bacillus thuringiensis Isolated from Acid Mine Drainage Site in Sabah, Malaysia

A Novel Device and Method for Assay of Bacterial Chemotaxis Towards Chemoattractants

Capillary assemblies and microfluidic devices used for bacterial chemotaxis assays have certain inherent limitations. This opens opportunities for innovation in the area. The present study describes an innovative economical device called chemotaxis plate and also a method to use this device for chemotaxis assay. Two type cultures, Pseudomonas putida MCC 2989 and Bacillus subtilis MCC 2049, chemotactic to L-aspartate, were used to validate the new device and establish the protocol for assay. 100 to 1000 fold higher number of cells were recovered in presence of chemoattractant as compared to control (p < 0.05). This novel assay technique showed 100% sensitivity and 99.21% specificity for chemotaxis assay of Pseudomonas putida MCC 2989 towards 3 mM L-aspartate over 50 min assay time. The device was also used to isolate bacteria chemotactic to caffeine directly from environmental samples. Very high chemotaxis response indices were reported for the first-time using chemotaxis plate.

Five copper homeostasis gene clusters encode the Cu-efflux resistome of the highly copper-tolerant Methylorubrum extorquens AM1

Background

In the last decade, the use of copper has reemerged as a potential strategy to limit healthcare-associated infections and to control the spread of multidrug-resistant pathogens. Numerous environmental studies have proposed that most opportunistic pathogens have acquired antimicrobial resistance in their nonclinical primary habitat. Thus, it can be presumed that copper-resistant bacteria inhabiting a primary commensal niche might potentially colonize clinical environments and negatively affect the bactericidal efficacy of Cu-based treatments. The use of copper in agricultural fields is one of the most important sources of Cu pollution that may exert selection pressure for the increase of copper resistance in soil and plant-associated bacteria. To assess the emergence of copper-resistant bacteria in natural habitats, we surveyed a laboratory collection of bacterial strains belonging to the order Rhizobiales. This study proposes that Methylorubrum extorquens AM1 is an environmental isolate well adapted to thrive in copper-rich environments that could act as a reservoir of copper resistance genes.

Methods

The minimal inhibitory concentrations (MICs) of CuCl₂ were used to estimate the copper tolerance of eight plant-associated facultative diazotrophs (PAFD) and five pink-pigmented facultative methylotrophs (PPFM) belonging to the order Rhizobiales presumed to come from nonclinical and nonmetal-polluted natural habitats based on their reported source of isolation. Their sequenced genomes were used to infer the occurrence and diversity of Cu-ATPases and the copper efflux resistome of Mr. extorquens AM1.

Results

These bacteria exhibited minimal inhibitory concentrations (MICs) of CuCl₂ ranging between 0.020 and 1.9 mM. The presence of multiple and quite divergent Cu-ATPases per genome was a prevalent characteristic. The highest copper tolerance exhibited by Mr. extorquens AM1 (highest MIC of 1.9 mM) was similar to that found in the multimetal-resistant model bacterium Cupriavidus metallidurans CH34 and in clinical isolates of Acinetobacter baumannii. The genome-predicted copper efflux resistome of Mr. extorquens AM1 consists of five large (6.7 to 25.7 kb) Cu homeostasis gene clusters, three clusters share genes encoding Cu-ATPases, CusAB transporters, numerous CopZ chaperones, and enzymes involved in DNA transfer and persistence. The high copper tolerance and the presence of a complex Cu efflux resistome suggest the presence of relatively high copper tolerance in environmental isolates of Mr. extorquens.

Whole genome sequence data of a marine bacterium, Marinobacter adhaerens PBVC038, associated with toxic harmful algal bloom

Marinobacter adhaerens (PBVC038) was isolated from a harmful algal bloom event caused by the toxic dinoflagellate Pyrodinium bahamense var. compressum (P. bahamense) in Sepanggar Bay, Sabah, Malaysia, in December 2012. Blooms of P. bahamense are frequently linked to paralytic shellfish poisoning, resulting in morbidity and mortality. Prior experimental evidence has implicated the role of symbiotic bacteria in bloom dynamics and the synthesis of biotoxins. The draft genome sequence data of a harmful algal bloom-associated bacterium, Marinobacter adhaerens PBVC038 is presented here. The genome is made up of 21 contigs with an estimated 4,246,508 bases in genome size and a GC content of 57.19%. The raw data files can be retrieved from the National Center for Biotechnology Information (NCBI) under the Bioproject number PRJNA320140. The assessment of bacterial communities associated with harmful algal bloom should be studied more extensively as more data is needed to ascertain the functions of these associated bacteria during a bloom event.

Genomic data of two Bacillus and two Pseudomonas strains isolated from the acid mine drainage site at Mamut Copper Mine, Ranau, Malaysia

The genomic data of four bacteria strains isolated from the abandoned Mamut Copper Mine, an Acid Mine Drainage (AMD) site is presented in this report. Two of these strains belong to the genus Bacillus, while the other two belong to the genus Pseudomonas. The draft genome size of Pseudomonas sp. strain MCMY3 was 6,396,595 bp (GC: 63.3%), Bacillus sp. strain MCMY6 was 6,815,573 bp (GC: 35.2%), Bacillus sp. strain MCMY13 was 5,559,059 bp (GC: 35.5%) and Pseudomonas sp. strain MCMY15 was 7,381,777 bp (GC: 64.8%). These four genomes contained 493, 495, 495 and 579 annotated subsystems, respectively. The sequence data are available at GenBank sequence read archive with accessions numbers SRX7859406, SRX7859404, SRX7859405 and SRX7293032 for strains MCMY3, MCMY6, MCMY13 and MCMY15, respectively.

The effect of plant growth-promoting rhizobacteria (PGPR) on arsenic accumulation and the growth of rice plants (Oryza sativa L.)

Large areas of paddy fields in southern China have been contaminated by arsenic (As), which causes serious problems such as the reduction of grain yield and high As concentrations in brown rice. To test the possibility of using plant growth-promoting rhizobacteria (PGPR) to promote rice growth and decrease As accumulation in brown rice in such paddy fields, three As-resistant PGPRs (strains S6, S7 and S10) were isolated and incorporated into two rice cultivars (Zhendao 14 and Jianyou G2) grown in different environments. The results showed that all PGPRs promoted rice growth (grain yield increased by 10.50-51.30% under greenhouse conditions and by 4.83-9.16% in paddy fields) and reduced As damage in rice. Specifically, S10 decreased As accumulation in brown rice in both greenhouse (3.50-26.01%) and paddy-field conditions (9.26-10.50%) by significantly reducing the available As concentration in rhizospheric soil, especially in the Dabaoshan-B field (34.00%). Conversely, in greenhouse condition, strains S6 and S7 increased As concentrations by 6.10-20.10% and 2.14-14.60%, respectively. Our results suggested that PGPR inoculation could be used to decrease As accumulation and promote rice growth in As-contaminated paddy fields. However, as the effects of PGPRs differed by strain and depended on environmental factors, careful selection of the strains and environmental conditions, and pre-testing, will be essential before applying PGPRs to As-contaminated paddy fields.

Draft Genome Sequence of Bacillus thuringiensis Strain UNMSM10RA, Isolated from Potato Crop Soil in Peru

The 5.5-Mb genome sequence of Bacillus thuringiensis strain UNMSM10RA, isolated from potato crop soil, is reported in this study. The strain UNMSM10RA contains 5,347 protein-coding sequences, 105 tRNA genes, 15 rRNA genes, and 5 noncoding RNA (ncRNA) genes, with an average G+C content of 35.1%.