The influence of microbiological fertilisers on the productivity and quality of winter wheat

The study was aimed at assessing the yield and quality of winter wheat grains inoculated with Beijerinckia fluminensis (Azotovit) and Paenibacillus mucilaginosus (Phosphatovit) in a three-year experiment on leached Chernozem in the forest-steppe zone of the Middle Volga region. The seeds of the plants were treated before sowing with microbiological fertilisers, both individually and together at a dose of 2 L/t. Bacteria Beijerinckia fluminensis and Paenibacillus mucilaginosus contained in fertilisers increased the resistance of plants to adverse conditions: seedling completeness increased by 5.4%, winter hardiness by 17.4%, and harvestability by 15.0%. The use of fertilisers led to an increase in the productivity of winter wheat grain to 32.4%. The technological parameters characterising the baking properties were improved: the content of crude gluten in the grain of winter wheat has increased to 29.1% at 75 GDI (gluten deformation index) units (I group (good) of gluten quality).

Impact of cultivation conditions on xylanase production and growth in Paenibacillus mucilaginosus

Xylanase is an enzyme that hydrolyses β-1,4 bonds in plant xylan. This enzyme is applied in the bioconversion of agro-industrial waste for xylooligosaccharide hydrolysate production to improve digestibility and nutrition value of animal feed, food processing, the utilisation and faster decomposition of crop debris in soil, as well as in cellulose bleaching and other industries. The current trend focuses on using renewable resources, such as agricultural waste, as substitutes for expensive purified xylan in producer screening and xylanase synthesis. This work aimed to determine the impact of Paenibacillus mucilaginosus cultivation conditions on the xylanase production yield. Rice bran ferment lysate along with birch and beech timber xylans were used as a carbon source. Temperature, medium pH, pH correction factors, inoculant incubation time, carbon and nitrogen sources and concentrations were the studied criteria of xylanase biosynthesis and growth in bacteria P. ucilaginosus strain 560. We show that the xylanase biosynthesis and cultivation in P. mucilaginosus strain 560 are more practical and cost-effective with the use of a rice bran ferment lysate-based nutrient medium. Inductors contained in the rice bran ferment lysate improve the xylanase biosynthesis. Calcium ions also facilitate biosynthesis in the studied strain. Cultivation recommendations are: carbon source concentration in medium 0.5% of total reducing substances content; 0.2% carbamide as optimal nitrogen source; calcium hydroxide as an agent for medium pH correction to 6.0±0.2; cultivation temperature 30±1 °С. Under the specified conditions, cultivation of P. mucilaginosus does not require inoculate preprocessing, and a maximal xylanase activity in stationary culture reaches 20 U/mL.

Simple rules govern the diversity of bacterial nicotianamine-like metallophores

In metal-scarce environments, some pathogenic bacteria produce opine-type metallophores mainly to face the host's nutritional immunity. This is the case of staphylopine, pseudopaline and yersinopine, identified in Staphylococcus aureus, Pseudomonas aeruginosa and Yersinia pestis, respectively. Depending on the species, these metallophores are synthesized by two (CntLM) or three enzymes (CntKLM), CntM catalyzing the last step of biosynthesis using diverse substrates (pyruvate or α-ketoglutarate), pathway intermediates (xNA or yNA) and cofactors (NADH or NADPH). Here, we explored the substrate specificity of CntM by combining bioinformatic and structural analysis with chemical synthesis and enzymatic studies. We found that NAD(P)H selectivity is mainly due to the amino acid at position 33 (S. aureus numbering) which ensures a preferential binding to NADPH when it is an arginine. Moreover, whereas CntM from P. aeruginosa preferentially uses yNA over xNA, the staphylococcal enzyme is not stereospecific. Most importantly, selectivity toward α-ketoacids is largely governed by a single residue at position 150 of CntM (S. aureus numbering): an aspartate at this position ensures selectivity toward pyruvate, whereas an alanine leads to the consumption of both pyruvate and α-ketoglutarate. Modifying this residue in P. aeruginosa led to a complete reversal of selectivity. Thus, the diversity of opine-type metallophore is governed by the absence/presence of a cntK gene encoding a histidine racemase, and the amino acid residue at position 150 of CntM. These two simple rules predict the production of a fourth metallophore by Paenibacillus mucilaginosus, which was confirmed in vitro and called bacillopaline.

Simple rules govern the diversity of bacterial nicotianamine-like metallophores

ABSTRACTIn metal-scarce environments, some pathogenic bacteria produce opine-type metallophores mainly to face the host’s nutritional immunity. This is the case of staphylopine, pseudopaline and yersinopine, identified inStaphylococcus aureus,Pseudomonas aeruginosaandYersinia pestisrespectively. These metallophores are synthesized by two (CntLM) or three enzymes (CntKLM), CntM catalyzing the last step of biosynthesis using diverse substrates (pyruvate or α-ketoglutarate), pathway intermediates (xNA or yNA) and cofactors (NADH or NADPH), depending on the species. Here, we explored substrate specificity of CntM by combining bioinformatics and structural analysis with chemical synthesis and enzymatic studies. We found that NAD(P)H selectivity was mainly due to the amino acid at position 33 (S. aureusnumbering) which ensures a preferential binding to NADPH when it is an arginine. Moreover, whereas CntM fromP. aeruginosapreferentially uses yNA over xNA, the staphylococcal enzyme is not stereospecific. Most importantly, selectivity towards α-ketoacids is largely governed by a single residue at position 150 of CntM (S. aureusnumbering): an aspartate at this position ensures selectivity towards pyruvate whereas an alanine leads to the consumption of both pyruvate and α-ketoglutarate. Modifying this residue inP. aeruginosaled to a complete reversal of selectivity. Thus, opine-type metallophore diversity is mainly mediated by the absence/presence of acntKgene encoding a histidine racemase, and the presence of an aspartate/alanine at position 150 of CntM. These two simple rules predict the production of a fourth metallophore byPaenibacillus mucilaginosus, which was confirmedin vitroand called bacillopaline.