Bacillus Licheniformis Strain Research Articles

Structure Assessment and Impacts of Lipids' Chemistry on the Structuration of Polyhydroxyalkanoate Biosynthesized by Bacillus licheniformis AZU-A5.

The current study exploited cheese whey supernatant (CWS) as a renewable resource for polyhydroxyalkanoates (PHAs) formation. Structure identification and investigating the influence of lipid membranes' chemistry on PHA structuration were detailed. Approximately 66 bacterial isolates from dairy products companies in Egypt were screened for PHA production, and the bacterial isolate AZU-A5, identified as Bacillus licheniformis strain AZU-A5, showed the highest production PHA 0.93 g L-1) using whey lactose. The highest PHA rate in the individual design was 1.59 g L-1 with a recovery yield of 33.08% (w w-1), while the production rate in the statistical design reached 1.75 g L-1 PHA and 51.60% PHA content. Structurally, the PHA was identified as polyhydroxy-3R-butyrate (R-PH3B). The fibrous texture by SEM highlighted the self-assembly of PHB. The CD analysis of the PHA films suggested favorable hydrophobic interactions between lipids and PHB. Higher lipid contents not only caused a decrement in the CD signal of PHB but also bathochromic effects occurred. The chain length of lipids exerted high impacts on interactions (CD) and structuration of PHB (Δλ). The unsaturation showed little influence on CD and negligible effect on Δλ, while the head group exerted no effect on CD with a considerable impact on Δλ.

Potential for the Bio-Detoxification of the Mycotoxins Enniatin B and Deoxynivalenol by Lactic Acid Bacteria and Bacillus spp.

Mycotoxins, toxic compounds produced by fungi, pose significant risks to food safety and human health. This study investigates the bio-detoxification potential of 238 strains of lactic acid bacteria (LAB) and Bacillus spp., previously isolated from cereals (including mycotoxin-contaminated grains), against the emerging mycotoxin, enniatin B (ENB), and the prevalent mycotoxin, deoxynivalenol (DON). Out of the tested strains, 26 demonstrated notable mycotoxin reduction capabilities, including 2 Bacillus pumilus and 24 Bacillus licheniformis strains. B. licheniformis strains MA572, MA695, MA696, TR174a, TR284, TR363, and TR466a degraded ENB to levels below the detection limit, and six strains reduced DON by 30-35%; B. licheniformis TR251b and TR374 showed the highest DON reduction with 35.7%. The most promising strains for bio-detoxification were B. licheniformis TR284, which achieved a 100% reduction in ENB and a 28.6% reduction in DON and B. licheniformis TR388 with a 97.5% reduction in ENB and a 31.9% reduction in DON. None of the tested LAB strains significantly reduced either mycotoxin. These findings highlight the promising potential of B. licheniformis strains in bio-detoxifying mycotoxin-contaminated cereal products. Further research into the underlying detoxification mechanisms and safety aspects is essential to develop effective bio-detoxification strategies for enhancing food safety.

Production of Amylase by Solid State Fermentation Using Agricultural Waste

This study presents a comprehensive investigation into the production of amylase, a crucial enzyme with wide-ranging industrial applications, using locally sourced substrates from Kachchh, Gujarat. The research employed the Bacillus licheniformis strain and substrates such as coconut, rice husk, wheat bran, paddy straw, and maize straw. The study found paddy straw to be the most promising substrate for amylase production. The research also systematically optimized various process parameters for amylase production in Solid-State Fermentation (SSF) using the One Variable at a Time (OVAT) method. These parameters included incubation period, temperature, inoculum level, additional carbon sources, starch concentrations, additional nitrogen sources, initial pH, different mineral salt ions, initial moisture level, and surfactants. The results showed that the optimal conditions for maximum amylase yield were an incubation period of 48 hours, an incubation temperature of 35°C, an inoculum level of 10%, starch as the additional carbon source, a starch concentration of 2.5%, yeast extract as the additional nitrogen source, an initial pH of 7, NaCl as the mineral salt, an initial moisture level of 75%, and Tween 80 as the surfactant. This research provides a reliable and sustainable approach to enzyme production, offering valuable insights for the optimization of the solid-state fermentation process for maximum amylase production.

Characterization, whole-genome sequence analysis, and protease production of a new thermophilic Bacillus licheniformis strain isolated from Debagh hot spring, Algeria.

A new thermophilic strain, designated as Bacillus sp. LMB3902, was isolated from Hammam Debagh, the hottest spring in Algeria (up to 98°C). This isolate showed high protease production in skim milk media at 55°C and exhibited significant specific protease activity by using azocasein as a substrate (157.50 U/mg). Through conventional methods, chemotaxonomic characteristics, 16S rRNA gene sequencing, and comparative genomic analysis with the closely related strain Bacillus licheniformis DSM 13 (ATCC 14580T), the isolate Bacillus sp. LMB3902 was identified as a potentially new strain of Bacillus licheniformis. In addition, the gene functions of Bacillus sp. LMB3902 strain were predicted using the Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Clusters of Orthologous Groups, Non-Redundant Protein Sequence Database, Swiss-Prot, and Pfam databases. The results showed that the genome size of Bacillus sp. LMB3902 was 4.279.557bp, with an average GC content of 46%. The genome contained 4.760 predicted genes, including 8 rRNAs, 78 tRNAs, and 24 sRNAs. A total of 235 protease genes were annotated including 50 proteases with transmembrane helix structures and eight secreted proteases with signal peptides. Additionally, the majority of secondary metabolites found by antiSMASH platform showed low similarity to identified natural products, such as fengicin (53%), lichenysin (57%), and surfactin (34%), suggesting that this strain may encode for novel uncharacterized natural products which can be useful for biotechnological applications. This study is the first report that describes the complete genome sequence, taxono-genomics, and gene annotation as well as protease production of the Bacillus genus in this hydrothermal vent.

Safety evaluation of the food enzyme β-galactosidase from the genetically modified Bacillus licheniformis strain DSM 34099.

The food enzyme β-galactosidase (β-d-galactoside galactohydrolase; EC 3.2.1.23) is produced with the genetically modified Bacillus licheniformis strain DSM 34099 by Kerry Group Services International, Ltd. (KGSI). The genetic modifications do not give rise to safety concerns. The food enzyme is free from viable cells of the production organism and its DNA. The production strain met the requirements for the qualified presumption of safety (QPS) approach. The food enzyme is intended to be used in two food manufacturing processes. Dietary exposure was estimated to be up to 7.263 mg total organic solids/kg body weight per day in European populations. Given the QPS status of the production strain and the absence of concerns resulting from the food enzyme manufacturing process, toxicity tests, other than an assessment of allergenicity, were considered unnecessary by the Panel. A search for the identity of the amino acid sequence of the food enzyme to known allergens was made and one match with a food allergen from kiwi fruit was found. The Panel considered that a risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to kiwi fruit, cannot be excluded. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Isolation of Bacillus licheniformis and its protective effect on liver oxidative stress and apoptosis induced by aflatoxin B1

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins. The use of probiotics is an effective approach to reduce aflatoxins content in foods. To find efficient bacterial species that can eliminate or detoxify AFB1, a bacterial strain S51 capable of degrading AFB1 was isolated from chicken intestine and soil samples by using a culture medium containing coumarin as the sole carbon source. Based on the results of 16S rRNA gene sequence analysis, this isolate (strain S51) was identified as Bacillus licheniformis strain QT338. Further characterization of strain S51 showed that it could degrade AFB1 by 61.3% after incubation at 30°C for 72 h. Additional studies demonstrated that S51 promoted good growth performance of the treated chickens, showed no hemolytic activity, carried few drug resistance genes, and exhibited a certain level of tolerance to acid and bile salts. Furthermore, to verify whether strain S51 exerts a protective effect on AFB1-induced liver injury in chickens and to elucidate the underlying mechanism, a chicken toxicity model was induced with AFB1 (100 μg/kg BW) and treated with S51(1×109CFU/mL) for 12 d. The results showed that S51 decreased the level of alanine transaminase, aspartate transaminase, and total bilirubin (P < 0.05); increased glutathione activity and total antioxidant capacityin the liver induced by AFB1, and decreased malondialdehyde production (P < 0.05). S51 also up-regulated the mRNA expression level of the antioxidant proteins HO-1 and Nrf2 and down-regulated the expression of the oxidation-related factor Keap1 in the Nrf2/Keap1 signaling pathway (P <0.05). S51 inhibited hepatocyte apoptosis induced by AFB1 and decreased the mRNA expression levels of the apoptosis-related genes Bax, caspase-3, caspase-9, and Cyt-C (P < 0.05). These results indicate that S51 regulates apoptosis and alleviates AFB1-induced oxidative stress in chicken liver by controlling the Nrf2/Keap1 signaling pathway.

Cr(VI) removal performance from wastewater by microflora isolated from tannery effluents in a semi-arid environment: a SEM, EDX, FTIR and zeta potential study.

Hexavalent chromium removal from the environment remains a crucial worldwide challenge. To address this issue, microbiological approaches are amongst the straightforward strategies that rely mainly on the bacteria's and fungi's survival mechanisms upon exposure to toxic metals, such as reduction, efflux system, uptake, and biosorption. In this work, scanning electron microscopy, energy-dispersive X-ray spectrophotometry, Fourier transform infrared spectroscopy, and zeta potential measurements were used to investigate the ability of chromium adsorption by Bacillus licheniformis, Bacillus megaterium, Byssochlamys sp., and Candida maltosa strains isolated from tannery wastewater. Scanning electron microscopy combined with energy dispersive X-ray spectroscopy revealed alterations in the cells treated with hexavalent chromium. When exposed to 50 mg/L Cr6+, Bacillus licheniformis and Candida maltosa cells become rough, extracellular secretions are reduced in Bacillus megaterium, and Byssochlamys sp. cells are tightly bound and exhibit the greatest Cr weight percentage. In-depth analysis of Fourier transform infrared spectra of control and Cr-treated cells unveiled Cr-microbial interactions involving proteins, lipids, amino acids, and carbohydrates. These findings were supported by zeta potential measurements highlighting significant variations in charge after treatment with Cr(VI) with an adsorption limit of 100 mg/L Cr6+ for all the strains. Byssochlamys sp. showed the best performance in Cr adsorption, making it the most promising candidate for treating Cr-laden wastewater.

Seasonal Survey of Bacterial Species and their Bioremediation Potentials in Leachates from a Nigerian Municipal Solid Waste Dumpsite

Myriads of microorganisms present in dumpsite leachates produce varieties of extracellular enzymes that can degrade toxic compounds to innocuous products. The present study involved a seasonal survey of bacterial species and their bioremediation potentials in leachate from the Ikueniro open solid waste dumpsite situated in Uhunmwode Local Government Area, Edo State, Nigeria. Bacterial isolation and enumeration of the leachate samples was carried out using pour plate technique. Phenotypic techniques and 16S rRNA gene analysis identified the bacterial isolates. The bacterial mastermix for bioremediation of the leachate consisted of a consortium of bacterial strains isolated from leachate discharging from the Ikhueniro dumpsite. The bioremediation efficiency of the leachate was deduced by measurement of heavy metals and other chemical analytes using standard methods prescribed by the American Public Health Association. The bacterial species isolated from Ikueniro dumpsite such as Bacillus licheniformis strain EGBON &amp; OKORIE 103 and Klebsiella aerogenes strain EGBON &amp; OKORIE 108 were deposited in the United States NCBI GenBank. A consortium of these bacterial strains served as inocula for the bioremediation setup. A huge removal of ammonia from the leachate was observed during the 28-day bioremediation experiment, amounting to a mean bioremediation efficiency of 80.65%. The removal of the heavy metals from the raw leachate by the bacterial mastermix in increasing order was as follows: nickel&lt;copper&lt;zinc&lt;lead&lt;iron&lt;cadmium&lt;arsenic&lt;mercury. Bioremediation of the leachate using indigenous bacteria promises to be an effective tool for management of toxicants from leachates of open solid waste dumpsites.

Safety evaluation of an extension of use of the food enzyme α-amylase from the non-genetically modified Bacillus licheniformis strain AE-TA.

The food enzyme α-amylase (4-α-d-glucan glucanohydrolase; EC 3.2.1.1) is produced with the non-genetically modified microorganism Bacillus licheniformis strain AE-TA by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in eight food manufacturing processes. Subsequently, the applicant has requested to extend its use to include one additional process and to revise the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme when used in a total of nine food manufacturing processes. As the food enzyme-total organic solids (TOS) are removed from the final foods in two food manufacturing processes, the dietary exposure to the food enzyme-TOS was estimated only for the remaining seven processes. Dietary exposure was calculated to be up to 0.382 mg TOS/kg body weight per day in European populations. Based on the data provided for the previous evaluation and the revised dietary exposure in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Characterization of Degraded Konjac Glucomannan from an Isolated Bacillus licheniformis Strain with Multi-Enzyme Synergetic Action.

The large molecular weight and high viscosity of natural konjac glucomannan (KGM) limit its industrial application. Microbial degradation of low-molecular-weight KGM has health benefits and various biological functions; however, the available KGM strains used in the industry have microbial contamination and low degradation efficiencies. Therefore, exploring novelly adaptable strains is critical for industrial processes. Here, the Bacillus licheniformis Z7-1 strain isolated from decaying konjac showed high efficiency for KGM degradation. The monosaccharide composition of the degradation products had a reduced molar ratio of mannose to glucose, indicating that Z7-1 preferentially degraded glucose in KGM. The degraded component was further characterized by ESI-MS, Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), and it also exhibited good antibacterial activity against various food-spoilage bacteria. Genome sequencing and zymolytic analysis revealed that abundant carbohydrate-active enzymes exist in the Z7-1 genome, with at least five types of extracellular enzymes responsible for KGM degradation, manifesting multi-enzyme synergetic action. The extracellular enzymes had significant thermal stability, indicating their potential application in industry. This study provides an alternative method for obtaining low-molecular-weight KGM with antibacterial functions and supports foundational knowledge for its development as a biocatalyst for the direct conversion of biomass polysaccharides into functional components.

Safety evaluation of the food enzyme α-amylase from the non-genetically modified Bacillus licheniformis strain AE-TA.

The food enzyme α-amylase (4-α-d-glucan glucanohydrolase; EC 3.2.1.1) is produced with the non-genetically modified microorganism Bacillus licheniformis strain AE-TA by Amano Enzyme Inc. The food enzyme is intended to be used in eight food manufacturing processes. Since residual amounts of food enzyme-total organic solids (TOS) are removed in two food manufacturing processes, dietary exposure was calculated only for the remaining six processes. It was estimated to be up to 0.056 mg TOS/kg body weight per day in European populations. The production strain of the food enzyme fulfils the requirements for the qualified presumption of safety approach to safety assessment. Consequently, in the absence of other concerns, the Panel considered that toxicological studies were not needed for the safety assessment of this food enzyme. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and two matches with respiratory allergens were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded (except for the production of distilled alcohol), but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Taxonomic identity of the Bacillus licheniformis strains used to produce food enzymes evaluated in published EFSA opinions.

Bacillus paralicheniformis, a species known to produce the antimicrobial bacitracin, could be misidentified as Bacillus licheniformis, depending on the identification method used. For this reason, the European Commission requested EFSA to review the taxonomic identification of formerly assessed B. licheniformis production strains. Following this request, EFSA retrieved the raw data from 27 technical dossiers submitted and found that the taxonomic identification was established by 16S rRNA gene analyses for 15 strains and by whole genome sequence analysis for 12 strains. As a conclusion, only these 12 strains could be unambiguously identified as B. licheniformis.

Enhanced biodegradation of phenol under Cr(VI) stress by microbial collaboration and potential application of machine learning for phenol biodegradation.

Cr(VI) and phenol commonly coexist in wastewater, posing a great threat to the environment and human health. However, it is still a challenge for microorganisms to degrade phenol under high Cr(VI) stress. In this study, the phenol-degrading strain Bacillus cereus ZWB3 was co-cultured with the Cr(VI)-reducing strain Bacillus licheniformis MZ-1 to enhance phenol biodegradation under Cr(Ⅵ) stress. Compared with phenol-degrading strain ZWB3, which has weak tolerance to Cr(Ⅵ), and Cr(Ⅵ)-reducing strain MZ-1, which has no phenol-degrading ability, the co-culture of two strains could significantly increase the degraded rate and capacity of phenol. In addition, the co-cultured strains exhibited phenol degradation ability over a wide pH range (7-10). The reduced content of intracellular proteins and polysaccharides produced by the co-cultured strains contributed to the enhancement of phenol degradation and Cr(Ⅵ) tolerance. The determination coefficients R2, RMSE, and MAPE showed that the BP-ANN model could predict the degradation of phenol under various conditions, which saved time and economic cost. The metabolic pathway of microbial degradation of phenol was deduced by metabolic analysis. This study provides a valuable strategy for wastewater treatment containing Cr(Ⅵ) and phenol.

Enhancing the Antibacterial Impact of Lipopeptide Extracted from Bacillus licheniformis as a Probiotic against MDR Acinetobacter baumannii.

The antibiotic resistance of microorganisms is escalating rapidly. Infections caused by opportunistic pathogens in immunocompromised individuals have prompted researchers to seek for potent and safe antibacterial agents. The purpose of this investigation was to explore the suppression of virulence gene expression, specifically the pga operon genes responsible in biofilm formation in Acinetobacter baumannii, through the utilization of metabolites obtained from probiotic bacteria. To assess the antimicrobial properties, standard strains of five probiotic bacteria were tested against a standard strain of multidrug-resistant (MDR) A. baumannii employing the agar gel diffusion technique. Following the identification of the most potent probiotic strain (Bacillus licheniformis), the existence of its LanA and LanM genes was confirmed using the polymerase chain reaction (PCR) test. High-performance liquid chromatography (HPLC) and fourier-transform infrared spectroscopy (FTIR) techniques were employed to identify the intended metabolite, which was found to be a lipopeptide nature. The minimum inhibitory concentration (MIC) values and anti-biofilm activity of the targeted metabolite were determined using a dilution method in 96-well microplates and field emission scanning electron microscopy (FE-SEM). Real-time PCR (qPCR) was utilized for comparing the expression of pga operon genes, including pgaABCD, in A. baumannii pre- and post-exposure to the derived lipopeptide. The MIC results indicated that the probiotic product inhibited the growth of A. baumannii at concentrations lower than those needed for conventional antibiotics. Furthermore, it was observed that the desired genes' expression decreased due to the effect of this substance. This research concludes that the B. licheniformis probiotic product could be a viable alternative for combating drug resistance in A. baumannii.

Characterisation of the Endophytic and Rhizospheric Bacillus licheniformis Strains Isolated from Sweet Potato with Plant Growth-Promoting and Yield Enhancing Potential

The primary aim of the present study was to identify bacterial isolates with yield-enhancing potential for application as biofertilisers in the cultivation of sweet potato. Therefore, endophytic and rhizospheric strains were isolated from sweet potato plantations in Hungary to identify bacterial strains with plant growth-promoting and antifungal potential. In total, seven Bacillus licheniformis strains were identified and subjected to detailed ecophysiological investigations. Experiments have been conducted to investigate the tolerance of selected strains to different limiting factors such as pH, temperature, and water activity, which affect survivability in various agricultural environments. The majority of tested B. licheniformis strains exhibited plant growth-promoting potential (e.g., production of indole-3-acetic acid up to 40.42 μg mL−1, production of ammonia up to 0.87 mg mL−1, phosphorus solubilising activity, siderophore production), with two strains (SZMC 27713 and SZMC 27715) demonstrating inhibitory activity (ranging between 7% and 38%) against plant pathogenic fungi prevalent in sweet potato cultivation. Furthermore, strain SZMC 27715 induced accelerated germination and a significantly higher germination rate in tomato seeds compared to the control. In a field study, it was observed that strain SZMC 27715 had a potent yield enhancing effect in sweet potato, where a significant yield per plant increase was observed in all treatments (1.13, 1.09 and 1.40 kg) compared to the control plants (0.92 kg). The highest yield per plant was observed when the cuttings were soaked combined with two additional foliar treatments. To the best of our knowledge, this is the first report of the successful utilisation of the B. licheniformis strain as a biofertiliser for yield enhancement in sweet potato cultivation. Based on our results, strain SZMC 27715 has potential for application as a biofertiliser in sweet potato cultivation either as a standalone option or in a microbial consortium.

Safety evaluation of the food enzyme subtilisin from the genetically modified Bacillus licheniformis strain NZYM-CB.

The food enzyme subtilisin (EC 3.4.21.62) is produced with the genetically modified Bacillus licheniformis strain NZYM-CB by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The food enzyme is considered free from viable cells of the production organism and its DNA. It is intended to be used in six food manufacturing processes. The dietary exposure to the food enzyme-TOS was estimated to be up to 0.722 mg TOS/kg body weight (bw) per day in European populations. The production strain of the food enzyme fulfils the requirements for the qualified presumption of safety approach to safety assessment. As no other concerns arising from the manufacturing process were identified, the Panel considered that toxicological tests were not required for the assessment of this food enzyme. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and 20 matches were found, including two food allergens (melon and pomegranate). The Panel considered that the risk of allergic reactions by dietary exposure cannot be excluded, particularly in individuals sensitised to melon and pomegranate, but would not exceed the risk from consumption of melon or pomegranate. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Safety evaluation of the food enzyme glutaminase from the genetically modified Bacillus licheniformis strain NZYM-JQ.

The food enzyme glutaminase (l-glutamine amidohydrolase EC 3.5.1.2) is produced with the genetically modified Bacillus licheniformis strain NZYM-JQ by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The production strain met the requirements for the qualified presumption of safety (QPS). The food enzyme is free from viable cells of the production organism and its DNA. The enzyme under assessment is intended to be used in six food manufacturing processes. Dietary exposure was estimated to be up to 0.148 mg TOS/kg body weight per day in European populations. Given the QPS status of the production strain and the absence of concern resulting from the food enzyme manufacturing process, toxicological studies were not considered necessary. A search was made for the similarity of the amino acid sequence to those of known allergens and one match with a pollen allergen was found. The Panel considered that the risk of allergic reactions by dietary exposure cannot be excluded, particularly for individuals sensitised to birch and oak pollen. The Panel concluded that the food enzyme does not give rise to safety concerns under the intended conditions of use.

Genotype-phenotype evaluation of the heterogeneity in biofilm formation by diverse Bacillus licheniformis strains isolated from dairy products

The spoilage bacterium Bacillus licheniformis has been identified as a quick and strong biofilm former in the dairy industry. In our previous study, intra-species variation in bacterial biofilms has been observed in diverse B. licheniformis strains from different genetic backgrounds; however, the mechanisms driving the observed heterogeneity of biofilms remain to be determined. In this study, the genotype-phenotype evaluation of the heterogeneity in biofilm formation of four B. licheniformis strains were examined. The heterogeneity in biofilm phenotype was accessed in aspects of bacterial growth and motility, cell viability, biofilm matrix production, and biofilm architectures. The underlying mechanisms of the intra-species variability in biofilms were also explored by whole genome resequencing (WGR). Results from bacterial motility tests showed a diverse motility among the strains, but there was no clear correlation between bacterial motility and biofilm formation. The cell viability results showed a different number of live cells in biofilms at the intra-species level. Analysis of chemical components in biofilm matrix demonstrated the great intra-species differences regarding extracellular matrix composition, and a negative correlation between biofilm formation on stainless steel and the protein: carbohydrate ratio in biofilm matrix was observed. Confocal laser scanning microscopy analysis also revealed the intra-species variability by showing great differences in general properties of B. licheniformis biofilms. WGR results identified important pathways involved in biofilm formation, such as two-component systems, quorum sensing, starch and sucrose metabolism, ABC transporters, glyoxylate and dicarboxylate metabolism, purine metabolism, and a phosphotransferase system. Overall, the above results emphasize the necessity of exploring the intra-species variation in biofilms, and would provide in-depth knowledge for designing efficient biofilm control strategies in the dairy industry.

Genome mining of Bacillus licheniformis MCC2514 for the identification of lasso peptide biosynthetic gene cluster and its characterization.

The probiotic strain Bacillus licheniformis MCC2514 has been shown to produce a strong antibacterial peptide and the whole genome sequence of this strain is also reported in our previous study. The present study is focused on the genome level investigation of this peptide antibiotic and its characterization. Genome mining of the culture revealed the presence of three putative bacteriocin clusters, viz. lichenicidin, sonorensin and lasso peptide. Hence, the mode of action of the peptide was investigated by reporter assay, scanning electron microscopy, and Fourier Transform Infrared spectroscopy. Additionally, the peptide treated groups of Kocuria rhizophila showed a reduction in the fold expression for transcription-related genes. The gene expression studies, quantitative β-galactosidase induction assay using the RNA stress reporter strain, yvgS along with the homology studies concluded that lasso peptide is responsible for the antibacterial activity of the peptide which acts as an inhibitor of RNA biosynthesis. Gene expression analysis showed a considerable increase in fold expression of lasso peptide genes at various fermentation hours. Also, the peptide was isolated, and its time-kill kinetics and minimum inhibitory concentration against the indicator pathogen K. rhizophila were examined. The peptide was also purified and the molecular weight was determined to be ~ 2kDa. Our study suggests that this bacteriocin can function as an effective antibacterial agent in food products as well as in therapeutics as it contains lasso peptide, which inhibits the RNA biosynthesis.

An impact of N-glycosylation on biochemical properties of a recombinant α-amylase from Bacillus licheniformis

Amylases are enzymes that are known to hydrolyze starch. High efficiency of amylolytic enzymes allows them to compete in the industry with the technology of chemical hydrolysis of starch. A Bacillus licheniformis strain with high amylolytic activity was isolated from soil and designated as T5. The gene encoding α-amylase from B. licheniformis T5 was successfully expressed in both Escherichia coli (rAmyT5-E) and Pichia pastoris (as rAmyT5-P). According to the study, the recombinant α-amylases rAmyT5-E and rAmyT5-P exhibited the highest activity at pH 6.0 and temperatures of 70 and 80 °C, respectively. Over 80% of the rAmyT5-E enzyme activity was preserved following incubation within the pH range of 5–9; the same was true for rAmyT5-P after incubation at pH 6–9. N-glycosylation reduced the thermal and pH stability of the enzyme. The specific activity and catalytic efficiency of the recombinant AmyT5 α-amylase were also diminished by N-glycosylation.