Speed dating for enzymes! Finding the perfect phosphopantetheinyl transferase partner for your polyketide synthase

The biosynthetic pathways for the fungal polyketides bikaverin and bostrycoidin, from Fusarium verticillioides and Fusarium solani respectively, were reconstructed and heterologously expressed in S. cerevisiae alongside seven different phosphopantetheinyl transferases (PPTases) from a variety of origins spanning bacterial, yeast and fungal origins. In order to gauge the efficiency of the interaction between the ACP-domains of the polyketide synthases (PKS) and PPTases, each were co-expressed individually and the resulting production of target polyketides were determined after 48 h of growth. In co-expression with both biosynthetic pathways, the PPTase from Fusarium verticillioides (FvPPT1) proved most efficient at producing both bikaverin and bostrycoidin, at 1.4 mg/L and 5.9 mg/L respectively. Furthermore, the remaining PPTases showed the ability to interact with both PKS’s, except for a single PKS-PPTase combination. The results indicate that it is possible to boost the production of a target polyketide, simply by utilizing a more optimal PPTase partner, instead of the commonly used PPTases; NpgA, Gsp and Sfp, from Aspergillus nidulans, Brevibacillus brevis and Bacillus subtilis respectively.

BIOREMEDIATION OF CHROMIUM (VI) BY A MICROBIAL CONSORTIUM ISOLATED FROM TANNERY EFFLUENTS AND THEIR POTENTIAL INDUSTRIAL APPLICATION

West Bengal has several leather industries and as such huge amount of leather are processed every year. The tannery effluents are discharged into the land and open water causing soil and water pollution respectively. Chromium is one of the most toxic inorganic contaminants which is well known for its carcinogenicity. Thus, our study focuses on investigating the bioremediation potential of common microflora isolated from tannery wastewater. In our study, Isolate 1 has the highest ability to reduce chromium (Cr6+) as compared to others. Isolate 4 has the highest protease, lipase and leather degradation activities. Isolate 1 shows the maximum keratinase activity making it an effective strain for keratinase production. Also, it has been found that pH 8 and temperature 40 °C was most suitable for keratinase production. Owing to the multidimensional ability of these two isolates, they were identified by 16S rRNA sequencing and it reveals that Isolate 1 and Isolate 4 belong to Bacillus cereus F4810/72 and Brevibacillus brevis F4810/72 respectively. Thus, this study establishes the role and efficiencies of these microorganisms in combatting pollution, particularly in the water bodies in which harmful chemicals leak regularly owing to improper waste management by various industries.

Identification of endophytic and rhizosphere bacteria in rice (Oryza sativa L.) in the experimental field at Payakumbuh State Agriculture Polytechnic, West Sumatra, Indonesia

The decrease of soil fertility and fewer soil microorganisms will lower crop production, particularly rice, thus threatening the national food security program. This study is (a) to isolate and identify the bacteria in the endophytic and rhizosphere of rice plants (b) to study the bacteria from the endophytic and rhizosphere of rice plants which potentially stimulate plant growth. The experiment was carried out at the Laboratory of Food Crop Cultivation at Payakumbuh State Agriculture Polytechnic, Limapuluh Kota Regency, West Sumatra for four months. The sampling method was carried out by random sampling at rice planting in the Payakumbuh State Agriculture Polytechnic Experimental Field. Endophytic bacteria were taken from the root tissue of rice plants, and rhizosphere bacteria were taken from a layer of soil around rice roots. Isolation of bacteria was carried out by using the pour plate and scratchplate methods. Four bacteria were identified using the 16S rRNA sequencing method. The identification results showed that in the rice root tissue found the bacteria Chromobacterium rhizoryzae and Brevibacillus brevis. In the rice rhizosphere, Bacillus pseudomycoides and Bacillus thuringiensis are found. Bacteria are dominated by the Bacillus genera which can stimulate plant growth.

Genome Sequence of Brevibacillus brevis HK544, an Antimicrobial Bacterium Isolated from Soil in Daejeon, South Korea

The Brevibacillus brevis HK544 strain, which was isolated from soil, exhibited antimicrobial activity against plant pathogens such as Botrytis cinerea , Phytophthora infestans , and Erwinia amylovora . Here, we report the draft genome sequence of the B. brevis HK544 strain, which consists of one circular chromosome of 6,486,246 bp with a GC content of 47.3%.

Plant Growth-Promoting Endophytic Bacterial Community Inhabiting the Leaves of Pulicaria incisa (Lam.) DC Inherent to Arid Regions

In this study, 15 bacterial endophytes linked with the leaves of the native medicinal plant Pulicaria incisa were isolated and identified as Agrobacterium fabrum, Acinetobacter radioresistant, Brevibacillus brevis, Bacillus cereus, Bacillus subtilis, Paenibacillus barengoltzii, and Burkholderia cepacia. These isolates exhibited variant tolerances to salt stress and showed high efficacy in indole-3-acetic acid (IAA) production in the absence/presence of tryptophan. The maximum productivity of IAA was recorded for B. cereus BI-8 and B. subtilis BI-10 with values of 117 ± 6 and 108 ± 4.6 μg mL−1, respectively, in the presence of 5 mg mL−1 tryptophan after 10 days. These two isolates had a high potential in phosphate solubilization and ammonia production, and they showed enzymatic activities for amylase, protease, xylanase, cellulase, chitinase, and catalase. In vitro antagonistic investigation showed their high efficacy against the three phytopathogens Fusarium oxysporum, Alternaria alternata, and Pythium ultimum, with inhibition percentages ranging from 20% ± 0.2% to 52.6% ± 0.2% (p ≤ 0.05). Therefore, these two endophytic bacteria were used as bio-inoculants for maize seeds, and the results showed that bacterial inoculations significantly increased the root length as well as the fresh and dry weights of the roots compared to the control plants. The Zea mays plant inoculated with the two endophytic strains BI-8 and BI-10 significantly improved (p ≤ 0.05) the growth performance as well as the nutrient uptake compared with an un-inoculated plant.

Biodegradation of selected hydrocarbons by novel bacterial strains isolated from contaminated Arabian Gulf sediment

Three strains of novel bacteria were isolated from oil-contaminated sediment from the Arabian Gulf (Brevibacillus brevis T2C2008, Proteus mirabilis T2A12001, and Rhodococcus quinshengi TA13008). The isolated strains were tested for their degrading efficacy of low and high molecular hydrocarbon (naphthalene and pyrene). The efficacy of the two-hydrocarbon degradation by the isolates bacterial was determined at a temperature of 25 °C and 37 °C and pH of 5.0 and 9.0. In inoculated media at 37 °C, Rhodococcus qinshengi fully metabolized naphthalene and degrade 56% of pyrene. Brevibacillus brevis break down over 80% of naphthalene at room temperatures (25 °C). However, it was found that P. mirabilis and R. qinshengi biodegraded nearly 94% of naphthalene in the incubated media. The capacity for pyrene and naphthalene degradation in varying pH and temperature conditions was shown to be significant in Rhodococcus qinshengi because of its mineralization exceeding 50% across the tested pH and temperature. This implies that the isolated strains are ideal for biodegradation of contaminated sediment with naphthalene and pyrene.

Evaluation of Entomopathogenic Bacteria Against Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspididae)

Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspidae) which has a wide host range, is an important pest causing losses in yield. The insecticides are used for control against this pest but insecticidal control is difficult as scales protect themselves very effectively with hard, waxy armor. Also, the negative effects of the chemicals used in the control against benefical insects and with the increasing awareness on environmental issues, alternative methods were sought. Therefore, this study was performed to develop an alternative and effective control method for this pest by using biocontrol bacteria Bacillus pumilus (TV-67C), Brevibacillus brevis (CP-1) and Bacillus megaterium (TV-91C) under controlled conditions. The death adult number of the pest was recorded and mortality rate was calculated. All of the tested bacterial strains showed mortality rates from 41.68% to 89.04% against the white peach scale under controlled conditions. Consequently, our results indicated that especially B. pumilus strain TV-67C and B. brevis strain CP-1 can be used as biocontrol agents of P. pentagona.

Cooperation, Competition, and Specialized Metabolism in a Simplified Root Nodule Microbiome

ABSTRACT Microbiomes associated with various plant structures often contain members with the potential to make specialized metabolites, e.g., molecules with antibacterial, antifungal, or siderophore activities. However, when and where microbes associated with plants produce specialized metabolites, and the potential role of these molecules in mediating intramicrobiome interactions, is not well understood. Root nodules of legume plants are organs devoted to hosting symbiotic bacteria that fix atmospheric nitrogen and have recently been shown to harbor a relatively simple accessory microbiome containing members with the ability to produce specialized metabolites in vitro. On the basis of these observations, we sought to develop a model nodule microbiome system for evaluating specialized microbial metabolism in planta. Starting with an inoculum derived from field-grown Medicago sativa nodules, serial passaging through gnotobiotic nodules yielded a simplified accessory community composed of four members: Brevibacillus brevis, Paenibacillus sp., Pantoea agglomerans, and Pseudomonas sp. Some members of this community exhibited clear cooperation in planta, while others were antagonistic and capable of disrupting cooperation between other partners. Using matrix-assisted laser desorption ionization–imaging mass spectrometry, we found that metabolites associated with individual taxa had unique distributions, indicating that some members of the nodule community were spatially segregated. Finally, we identified two families of molecules produced by B. brevis in planta as the antibacterial tyrocidines and a novel set of gramicidin-type molecules, which we term the britacidins. Collectively, these results indicate that in addition to nitrogen fixation, legume root nodules are likely also sites of active antimicrobial production.

Optimization of staining with SYTO 9/propidium iodide: interplay, kinetics and impact on Brevibacillus brevis

Fluorophores SYTO 9 and propidium iodide (PI) are extensively applied in medicine, food industry and environmental monitoring to assess the viability of bacteria. However, the actual performance of these dyes remains largely unknown. In addition, their effects on the physiology of cells have not been elucidated. Here we characterized the effects of these two dyes on Brevibacillus brevis under optimized staining. We found that SYTO 9 entered cells continuously while PI tended to adhere to the cell wall before entering the cell. In addition, results showed that a high amount of the dyes altered the physicochemical properties of membranes, improving their breakthrough. These results provide new perspectives and ideas for improving the characterization of bacterial viability using flow cytometry.