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Bacterial lipases with activity spanning over a broad temperature and substrate range have several industrial applications. An efficient enzyme-producing bacterium Chryseobacterium polytrichastri ERMR1:04, previously reported from Sikkim Himalaya, was explored for purification and characterization of cold-adapted lipase. Optimum lipase production was observed in 1% (v/v) rice bran oil, pH 7 at 20°C. Size exclusion and hydrophobic interaction chromatography purified the enzyme up to 21.3-fold predicting it to be a hexameric protein of 250 kDa, with 39.8 kDa monomeric unit. MALDI-TOF-MS analysis of the purified lipase showed maximum similarity with alpha/beta hydrolase (lipase superfamily). Biochemical characterization of the purified enzyme revealed optimum pH (8.0), temperature (37°C) and activity over a temperature range of 5–65°C. The tested metals (except Cu2+ and Fe2+) enhanced the enzyme activity and it was tolerant to 5% (v/v) methanol and isopropanol. The Km and Vmax values were determined as 0.104 mM and 3.58 U/mg, respectively for p -nitrophenyl palmitate. Bioinformatics analysis also supported in vitro findings by predicting enzyme's broad temperature and substrate specificity. The compatibility of the purified lipase with regular commercial detergents, coupled with its versatile temperature and substrate range, renders the given enzyme a promising biocatalyst for potential detergent formulations.

Grain legumes are important sources of proteins, essential micronutrients and vitamins and for human nutrition. Climate change, including drought, is a severe threat to grain legume production throughout the world. In this review, the morpho-physiological, physio-biochemical and molecular levels of drought stress in legumes are described. Moreover, different tolerance mechanisms, such as the morphological, physio-biochemical and molecular mechanisms of legumes, are also reviewed. Moreover, various management approaches for mitigating the drought stress effects in grain legumes are assessed. Reduced leaf area, shoot and root growth, chlorophyll content, stomatal conductance, CO2 influx, nutrient uptake and translocation, and water-use efficiency (WUE) ultimately affect legume yields. The yield loss of grain legumes varies from species to species, even variety to variety within a species, depending upon the severity of drought stress and several other factors, such as phenology, soil textures and agro-climatic conditions. Closure of stomata leads to an increase in leaf temperature by reducing the transpiration rate, and, so, the legume plant faces another stress under drought stress. The biosynthesis of reactive oxygen species (ROS) is the most detrimental effect of drought stress. Legumes can adapt to the drought stress by changing their morphology, physiology and molecular mechanism. Improved root system architecture (RSA), reduced number and size of leaves, stress-induced phytohormone, stomatal closure, antioxidant defense system, solute accumulation (e.g., proline) and altered gene expression play a crucial role in drought tolerance. Several agronomic, breeding both conventional and molecular, biotechnological approaches are used as management practices for developing a drought-tolerant legume without affecting crop yield. Exogenous application of plant-growth regulators (PGRs), osmoprotectants and inoculation by Rhizobacteria and arbuscular mycorrhizal fungi promotes drought tolerance in legumes. Genome-wide association studies (GWASs), genomic selection (GS), marker-assisted selection (MAS), OMICS-based technology and CRISPR/Cas9 make the breeding work easy and save time in the developmental cycle to get resistant legumes. Several drought-resistant grain legumes, such as the chickpea, faba bean, common bean and pigeon pea, were developed by different institutions. Drought-tolerant transgenic legumes, for example, chickpeas, are developed by introgressing desired genes through breeding and biotechnological approaches. Several quantitative trait loci (QTLs), candidate genes occupying drought-tolerant traits, are identified from a variety of grain legumes, but not all are under proper implementation. Hence, more research should be conducted to improve the drought-tolerant traits of grain legumes for avoiding losses during drought.

Vicine and convicine may be removed from faba bean by hydrolysis to the corresponding aglycones, divicine and isouramil. For total elimination of their toxicity, further degradation of the aglycones should be shown. The aim of the study was to investigate hydrolysis of vicine and convicine using the enzymatic activity in faba bean in flour suspensions and selected lactic acid bacteria used as starters for faba bean fermentation. In addition, the effect of acidity on the stability of vicine and convicine was investigated. Sourdoughs were used in a baking process to obtain breads as final products. Vicine, convicine, and their aglycones were analyzed using reversed phase high pressure liquid chromatography with UV detection (RP-HPLC-UV). Incubation of the suspensions showed rather small vicine and convicine losses. Acidity itself did not cause losses under the conditions studied, apart from that of convicine at low pH. In sourdough fermentation with strains of Lactobacillus plantarum and Pediococcus pentosaceus, losses of vicine and convicine were dependent on the fermentation temperature and the β-glucosidase activity of the starter. Compared to fermentation at 20 °C, more intense acidification at 25 °C resulted in decrease of vicine up to 85% and convicine up to 47%. Levels of vicine and convicine in breads were comparable to levels in sourdoughs. Furthermore, the aglycones were not detected from breads.

Biological nitrogen fixation (BNF) plays a crucial role in nitrogen utilization in agroecosystems. Functional characteristics of plants (grasses vs. legumes) affect BNF. However, little is still known about how ecological zones and cropping patterns affect legume nitrogen fixation. This study's objective was to assess the effects of different cropping systems on aboveground dry matter, interspecific relationships, nodulation characteristics, root conformation, soil physicochemistry, BNF, and nitrogen transfer in three ecological zones and determine the main factors affecting nitrogen derived from the atmosphere (Ndfa) and nitrogen transferred (Ntransfer). The N labeling method was applied. Oats ( L.), forage peas ( L.), common vetch ( L.), and fava beans ( L.) were grown in monocultures and mixtures (YS: oats and forage peas; YJ: oats and common vetch; YC: oats and fava beans) in three ecological regions (HZ: Huangshui Valley; GN: Sanjiangyuan District; MY: Qilian Mountains Basin) in a split-plot design. The results showed that mixing significantly promoted legume nodulation, optimized the configuration of the root system, increased aboveground dry matter, and enhanced nitrogen fixation in different ecological regions. The percentage of nitrogen derived from the atmosphere (%Ndfa) and percentage of nitrogen transferred (%Ntransfer) of legumes grown with different legume types and in different ecological zones were significantly different, but mixed cropping significantly increased the %Ndfa of the legumes. Factors affecting Ndfa included the cropping pattern, the ecological zone (R), the root nodule number, pH, ammonium-nitrogen, nitrate-nitrogen, microbial nitrogen mass (MBN), plant nitrogen content (N%), and aboveground dry biomass. Factors affecting Ntransfer included R, temperature, altitude, root surface area, nitrogen-fixing enzyme activity, organic matter, total soil nitrogen, MBN, and N%. We concluded that mixed cropping is beneficial for BNF and that mixed cropping of legumes is a sustainable and effective forage management practice on the Tibetan Plateau.

Salmonella and Escherichia coli (E. coli) food contamination could lead to serious foodborne diseases. The gradual increase in the incidence of foodborne disease invokes new and efficient methods to limit food pathogenic microorganism contamination. In this study, a polyvalent broad-spectrum Escherichia phage named Tequatrovirus EP01 was isolated from pig farm sewage. It could lyse both Salmonella Enteritidis (S. Enteritidis) and E. coli and exhibited broad host range. EP01 possessed a short latent period (10 min), a large burst size (80 PFU/cell), and moderate pH stability (4–10) and appropriate thermal tolerance (30–80 °C). Electron microscopy and genome sequence revealed that EP01 belonged to T4-like viruses genus, Myoviridae family. EP01 harbored 12 CDSs associated with receptor-binding proteins and lacked virulence genes and drug resistance genes. We tested the inhibitory effect of EP01 on S. Enteritidis, E. coli O157:H7, E. coli O114:K90 (B90), and E. coli O142:K86 (B) in liquid broth medium (LB). EP01 could significantly reduce the counts of all tested strains compared with phage-free groups. We further examined the effectiveness of EP01 in controlling bacterial contamination in two kinds of foods (meat and milk) contaminated with S. Enteritidis, E. coli O157:H7, E. coli O114:K90 (B90), and E. coli O142:K86 (B), respectively. EP01 significantly reduced the viable counts of all the tested bacteria (2.18–6.55 log10 CFU/sample, p < 0.05). A significant reduction of 6.55 log10 CFU/cm2 (p < 0.001) in bacterial counts on the surface of meat was observed with EP01 treatment. Addition of EP01 at MOI of 1 decreased the counts of bacteria by 4.3 log10 CFU/mL (p < 0.001) in milk. Generally, the inhibitory effect exhibited more stable at 4 °C than that at 28 °C, whereas the opposite results were observed in milk. The antibacterial effects were better at MOI of 1 than that at MOI of 0.001. These results suggests that phage EP01-based method is a promising strategy of controlling Salmonella and Escherichia coli pathogens to limit microbial food contamination.

Broad bean paste (BBP) is a traditional fermented soy food, and its high salt content not only prolongs the fermentation time but also threatens human health. In this study, three BBP-meju with different salt concentrations were prepared, and the effects of varying salinity on fermentation were comprehensively compared. The results showed that salt-reduced fermentation contributed to the accumulation of amino acid nitrogen, reducing sugars, free amino acids, and organic acids. Alcohols, esters, aldehydes, and acids were the main volatile flavor compounds in BBP-meju, and the highest total volatile flavor compounds were found in medium-salt meju. Bacillus, Staphylococcus, Aspergillus, and Mortierella were the dominant microbial communities during fermentation, and there were also three opportunistic pathogens, Enterobacter, Pantoea, and Brevundimonas, respectively. According to Spearman correlation analysis, Wickerhamomyces, Bacillus, Staphylococcus, and Mortierella all showed highly significant positive correlations with ≥3 key flavor compounds, which may be the core functional flora. Furthermore, the dominant microbial genera worked synergistically to promote the formation of high-quality flavor compounds and inhibit the production of off-flavors during salt-reduced fermentation. This study provides a theoretical reference for the quality and safety control of low-salt fermented soy foods.

Dried parsley is regularly contaminated with foodborne pathogens, especially Salmonella. Application of contaminated ingredients in ready-to-eat dishes without further thermal treatment represents a considerable health risk. This study examined the suitability of pulsed light as a novel decontamination method of Salmonella in dried parsley, along with the impact on selected quality parameters (chlorophyll content, phenolic compounds, color, and odor) and product characters (temperature and water activity value). Samples were inoculated with one of three Salmonella isolates (Salmonella Cerro or one of two isolates of Salmonella Agona) at two contamination levels of 103 or 107 CFU/g and treated under various experimental factors, including distance to the light source and exposure time, resulting in fluences in the range of 1.8 to 19.9 J/cm2. At selected parameter settings (9.8 and 13.3 J/cm2), the effect of prolonged storage time (48 h) of inoculated samples before treatment on the reduction of Salmonella Cerro was examined. Samples treated at the same fluences were also stored for 35 days at 22 to 25°C. The three Salmonella isolates were significantly reduced by pulsed light (P < 0.05). Reduction factors ranged between 0.3 and 5.2 log CFU with varying sensitivities of the isolates. In general, increasing fluences (depending on exposure time and distance to the light source) resulted in increasing reductions of Salmonella. However, on closer examination, exposure time and distance to the light source had a varying influence on the reduction of the different Salmonella isolates. Decreasing reduction factors were observed by increasing the contamination level and prolonging the storage time of inoculated samples before treatment. No undesirable changes in quality parameters and sensory analysis were detectable at fluences of 9.8 and 13.3 J/cm2, indicating that pulsed light may be a suitable alternative for the decontamination of dried parsley.

In this study, different drying methods, including hot air drying, sun drying, and freeze drying were employed to dry fresh broad beans. The nutritional composition, volatile organic components and bioactive substances of the dried broad beans were systematically compared. The results indicated significant differences (p < 0.05) in nutritional composition, such as protein and soluble sugar content. Among the 66 identified volatile organic compounds, freeze drying and hot air drying significantly promote the production of alcohols and aldehydes, while sun drying effectively preserves esters. In terms of bioactive substances, broad beans dried by freeze drying exhibit the highest total phenol content as well as the strongest antioxidant capacity and gallic acid, followed by sun drying. The chemometric analysis revealed that the bioactive compounds in broad beans dried by three different methods were primarily composed of flavonoids, organic acids, and amino acids with significant differentiation. Notably, freeze-dried and sun-dried broad beans exhibited a higher concentration of differential substances.

A bacteriocin from Bacillus subtilis (MK733983) originated from ethnomedicinal plant was purified using Preparative RP-HPLC. The HPLC fraction eluted with 65% acetonitrile showed the highest antimicrobial activity with Mycobacterium smegmatis as an indicator. Its specific activity and purification fold increased by 70.5% and 44%, respectively, compared to the crude bacteriocin. The bacteriocin showed stability over a wide range of pH (3.0–8.0) and preservation (− 20 °C and 4 °C), also thermal stability up to 80 °C for 20 min. Its proteinaceous nature was confirmed with complete loss of activity on its treatment with Trypsin, Proteinase K, and α-Chymotrypsin. Nevertheless, the bacteriocin retained up to 45% activity with Papainase treatment and was unaffected by salivary Amylase. It maintained ~ 95% activity on UV exposure up to 3 h and its activity was augmented by ethyl alcohol and metal ions like Fe2+ and Mn2+. Most of the common organic solvents, general surfactants, preservatives, and detergents like Sulfobetaine-14, Deoxy-cholic-acid did not affect the bacteriocin’s action. Its molecular weight was estimated to be 3.4KDa by LC-ESI-MS/MS analysis. The bacteriocin is non-hemolytic and exhibited a broad inhibition spectrum with standard strains of Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Chromobacterium violaceum with MICs ranging 0.225 ± 0.02–0.55 ± 0.05 mg/mL. Scanning Electron Microscopy showed cell annihilation with pores in cell membranes of S. aureus and P. aeruginosa treated with the bacteriocin, implicating bactericidal mode of action. These promising results suggest that the bacteriocin is significant and has wide-ranging application prospects.

The extensive growth of fruit and vegetable processing industries has led to the production of a large amount of by-products (including skin, peel, seeds and pulp) that contain large amounts of bioactive compounds such as polyphenols, polysaccharides and dietary fibers. Therefore, this study was conducted to optimize the polysaccharide extracted by ultrasound-assisted extraction in terms of yield, total phenolic content and antioxidant activity using the Box–Behnken design. The models exhibited that the parameters affecting the desired responses were temperature, time, and ultrasonic amplitude, with optimum values of 65 °C, 50 min, and 50%. Based on the results, the extraction yield, total phenolic content and EC 50 in optimal conditions were estimated as 15.58%, 87.99 mg GAE/100 g, and 334.09 µg/mL, respectively. The molecular weight of polysaccharide from faba bean pod (PFBP) was estimated to be 230 kDa. Galacturonic acid (57.75%), xylose (16.87%), and glucose (15.68) were identified as the dominant compounds of PFBP. Experimental data revealed that PFBP can be introduced as a valuable natural component for food supplements due to its good antioxidant activity and high, total phenolic content. Graphical abstract