High cell density sequential batch fermentation for enhanced propionic acid production from glucose and glycerol/glucose mixture using Acidipropionibacterium acidipropionici.

BACKGROUND: Propionic acid fermentation from renewable feedstock suffers from low volumetric productivity and final product concentration, which limits the industrial feasibility of the microbial route. High cell density fermentation techniques overcome these limitations. Here, propionic acid (PA) production from glucose and a crude glycerol/glucose mixture was evaluated using Acidipropionibacterium acidipropionici, in high cell density (HCD) batch fermentations with cell recycle. The agro-industrial by-product, heat-treated potato juice, was used as N-source. RESULTS: Using 40 g/L glucose for nine consecutive batches yielded an average of 18.76 ± 1.34 g/L of PA per batch (0.59 gPA/gGlu) at a maximum rate of 1.15 gPA/L.h, and a maximum biomass of 39.89 gCDW/L. Succinic acid (SA) and acetic acid (AA) were obtained as major by-products and the mass ratio of PA:SA:AA was 100:23:25. When a crude glycerol/glucose mixture (60 g/L:30 g/L) was used for 6 consecutive batches with cell recycle, an average of 35.36 ± 2.17 g/L of PA was obtained per batch (0.51 gPA/gC-source) at a maximum rate of 0.35 g/L.h, and reaching a maximum biomass concentration of 12.66 gCDW/L. The PA:SA:AA mass ratio was 100:29:3. Further addition of 0.75 mg/L biotin as a supplement to the culture medium enhanced the cell growth reaching 21.89 gCDW/L, and PA productivity to 0.48 g/L.h, but also doubled AA concentration. CONCLUSION: This is the highest reported productivity from glycerol/glucose co-fermentation where majority of the culture medium components comprised industrial by-products (crude glycerol and HTPJ). HCD batch fermentations with cell recycling are promising approaches towards industrialization of the bioprocess.

Carboligation of 5-(hydroxymethyl)furfural via whole-cell catalysis to form C12 furan derivatives and their use for hydrazone formation.

BACKGROUND: Biobased 5-(hydroxymethyl)furfural (5-HMF) is an important platform that offers numerous possibilities for upgrading to a range of chemical, material and fuel products. One reaction of special interest is the carboligation of 5-HMF into C12 compounds, including 5,5'-bis(hydroxymethyl)furoin (DHMF) and its subsequent oxidation to 5,5'-bis(hydroxymethyl)furil (BHMF), due to their potential applications as building blocks for polymers and hydrocarbon fuels. OBJECTIVES: This study was aimed at evaluating the use of whole cells of Escherichia coli carrying recombinant Pseudomonas fluorescens benzaldehyde lyase as biocatalysts for 5-HMF carboligation, recovery of the C12 derivatives DHMF and BHMF, and testing the reactivity of the carbonyl groups for hydrazone formation for potential use as cross-linking agents in surface coatings. The effects of different parameters on the reaction were investigated to find the conditions for achieving high product yield and productivity. RESULTS: The reaction with 5 g/L 5-HMF using 2 gCDW/L recombinant cells in 10% dimethyl carbonate, pH 8.0 at 30 °C resulted in DHMF yield of 81.7% (0.41 mol/mol) at 1 h, and BHMF yield of 96.7% (0.49 mol/mol) at 72 h reaction time. Fed-batch biotransformation generated a maximum DHMF concentration of 53.0 g/L (or 26.5 g DHMF/g cell catalyst) with productivity of 10.6 g/L.h, after five feeds of 20 g/L 5-HMF. Both DHMF and BHMF reacted with adipic acid dihydrazide to form hydrazone that was confirmed by Fourier-transform infrared spectroscopy and 1H NMR. CONCLUSION: The study demonstrates the potential application of recombinant E. coli cells for cost-effective production of commercially relevant products.

Usage Pattern of Fixed-dose Combinations at ICMR Network of Rational Use of Medicine Centres across India: Recommendations for Policymakers and Prescribers.

AIM: Irrational use of medicines is a global problem. In India, one contributing factor is the availability of a large number of fixed-dose combinations (FDCs). To improve rational use and to strengthen policies, it is important to assess the usage patterns and rationality of FDCs. METHODS: This study was conducted as part of a 1-year prospective cross-sectional analysis of prescriptions in the outpatient clinics of broad specialities from 13 tertiary care hospitals across India. Five most commonly prescribed FDCs in each center were analyzed. In addition, all the prescribed FDCs were classified as per the Kokate Committee classification and it was noted whether any of the FDCs were irrational or banned as per the reference lists released by regulatory authorities. RESULTS: A total of 4,838 prescriptions were analyzed. Of these, 2,093 (43.3%) prescriptions had at least one FDC. These 2,093 prescriptions had 366 different FDCs. Of the 366 FDCs, 241 were rational; 10 were irrational; 14 required further data generation; and the remaining 96 FDCs could not be categorized into any of the above. Vitamins and minerals/supplements, antibacterial for systemic use, and drugs for gastroesophageal reflux disease (GERD) and peptic ulcer were the most used FDCs. CONCLUSION: Based on the finding that some prescriptions contained irrational FDCs, it is recommended that a rigorous, regular, and uniform method of evaluation be implemented to approve/ban FDCs and that prescribers be periodically notified about the status of the bans.

Membrane-based continuous fermentation with cell recycling for propionic acid production from glycerol by Acidipropionibacterium acidipropionici.

BACKGROUND: Microbial production of propionic acid (PA) from renewable resources is limited by the slow growth of the producer bacteria and product-mediated inhibition. The present study evaluates high cell density continuous PA fermentation from glycerol (Gly) using Acidipropionibacterium acidipropionici DSM 4900 in a membrane-based cell recycling system. A ceramic tubular membrane filter of 0.22 µm pore size was used as the filtering device for cell recycling. The continuous fermentations were run sequentially at dilution rates of 0.05 and 0.025 1/h using varying glycerol concentrations and two different yeast extract concentrations. RESULTS: PA volumetric productivity of 0.98 g/L.h with a product yield of 0.38 gPA/gGly was obtained with 51.40 g/L glycerol at a yeast extract concentration of 10 g/L. Increasing the glycerol and yeast extract concentrations to 64.50 g/L and 20 g/L, respectively, increased in PA productivity, product yield, and concentration to 1.82 g/L.h, 0.79 gPA/gGly, and 38.37 g/L, respectively. However, lowering the dilution rate to 0.025 1/h reduced the production efficiency. The cell density increased from 5.80 to 91.83 gCDW/L throughout the operation, which lasted for a period of 5 months. A tolerant variant of A. acidipropoinici exhibiting growth at a PA concentration of 20 g/L was isolated at the end of the experiment. CONCLUSIONS: Applying the current approach for PA fermentation can overcome several limitations for process industrialization.

A facile process for adipic acid production in high yield by oxidation of 1,6-hexanediol using the resting cells of Gluconobacter oxydans.

BACKGROUND: Adipic acid (AA) is one of the most important industrial chemicals used mainly for the production of Nylon 6,6 but also for making polyurethanes, plasticizers, and unsaturated polyester resins, and more recently as a component in the biodegradable polyester poly(butylene adipate terephthalate) (PBAT). The main route for AA production utilizes benzene as feedstock and generates copious amounts of the greenhouse gas NO2. Hence, alternative clean production routes for AA from renewable bio-based feedstock are drawing increasing attention. We have earlier reported the potential of Gluconobacter oxydans cells to oxidize 1,6-hexanediol, a potentially biobased diol to AA. RESULTS: The present report involves a study on the effect of different parameters on the microbial transformation of 1,6-hexanediol to adipic acid, and subsequently testing the process on a larger lab scale for achieving maximal conversion and yield. Comparison of three wild-type strains of G. oxydans DSM50049, DSM2003, and DSM2343 for the whole-cell biotransformation of 10 g/L 1,6-hexanediol to adipic acid in batch mode at pH 7 and 30 °C led to the selection of G. oxydans DSM50049, which showed 100% conversion of the substrate with over 99% yield of adipic acid in 30 h. An increase in the concentrations of the substrate decreased the degree of conversion, while the product up to 25 g/L in batch and 40 g/L in fed-batch showed no inhibition on the conversion. Moreover, controlling the pH of the reaction at 5-5.5 was required for the cascade oxidation reactions to work. Cell recycling for the biotransformation resulted in a significant decrease in activity during the third cycle. Meanwhile, the fed-batch mode of transformation by intermittent addition of 1,6-hexanediol (30 g in total) in 1 L scale resulted in complete conversion with over 99% yield of adipic acid (approximately 37 g/L). The product was recovered in a pure form using downstream steps without the use of any solvent. CONCLUSION: A facile, efficient microbial process for oxidation of 1,6-hexanediol to adipic acid, having potential for scale up was demonstrated. The entire process is performed in aqueous medium at ambient temperatures with minimal greenhouse gas emissions. The enzymes involved in catalyzing the oxidation steps are currently being identified.

Knowledge, attitude, and practice survey on antimicrobial use and resistance among Indian clinicians: A multicentric, cross-sectional study.

Purpose: This multicentric questionnaire-based study was undertaken to address the lack of systematic background data on the knowledge, attitudes, and practices among Indian physicians related to antimicrobial use and resistance. Materials and Methods: A validated structured study questionnaire was used for capturing respondent particulars, antimicrobial prescribing habits, knowledge of antimicrobial resistance (AMR), ways of choosing and learning about antibiotics, agreement or disagreement with certain perceptions regarding antibiotics, selection of antibiotics in specific settings, and suggestions regarding rationalizing antimicrobial use in the practice setting. Summary statistical analysis of the pooled data was done. Results: Five hundred and six respondents with a mean (standard deviation) age of 31.4 (8.71) years participated in the study. Three hundred and twenty-seven were medical and 179 surgical discipline clinicians. Overall, the theoretical knowledge about antimicrobials was satisfactory, but areas of concern were noted in the attitude and practice domains. A substantial proportion of participants failed to identify the correct choice of antibiotics in the case-based scenarios. 38.33% reported not attending a single continuing medical education on antimicrobials during the past year. Statistically significant differences were not observed in the KAP quotient scores between medical and surgical discipline respondents. Conclusions: Despite satisfactory background knowledge regarding the rational use of antimicrobials and AMR patterns, there are discrepancies in the physicians' prescribing attitude and thus strengthen the case for instituting specific interventions to improve antimicrobial prescribing.

Reviewing a plethora of oxidative-type reactions catalyzed by whole cells of Streptomyces species.

Selective oxidation reactions represent a challenging task for conventional organic chemistry. Whole-cell biocatalysis provides a very convenient, easy to apply method to carry out different selective oxidation reactions including chemo-, regio-, and enantio-selective reactions. Streptomyces species are important biocatalysts as they can catalyze these selective reactions very efficiently owing to the wide diversity of enzymes and enzymatic cascades in their cell niche. In this review, we present and analyze most of the examples reported to date of oxidative reactions catalyzed by Streptomyces species as whole-cell biocatalysts. We discuss 33 different Streptomyces species and strains and the role they play in different oxidative reactions over the past five decades. The oxidative reactions have been classified into seven categories that include: hydroxylation of steroids/non-steroids, asymmetric sulfoxidations, oxidation of aldehydes, multi-step oxidations, oxidative cleavage, and N-oxidations. The role played by Streptomyces species as recombinant hosts catalyzing bio-oxidations has also been highlighted.

Oxidation of 5-hydroxymethylfurfural with a novel aryl alcohol oxidase from Mycobacterium sp. MS1601.

Bio-based 5-hydroxymethylfurfural (HMF) serves as an important platform for several chemicals, among which 2,5-furan dicarboxylic acid (FDCA) has attracted considerable interest as a monomer for the production of polyethylene furanoate (PEF), a potential alternative for fossil-based polyethylene terephthalate (PET). This study is based on the HMF oxidizing activity shown by Mycobacterium sp. MS 1601 cells and investigation of the enzyme catalysing the oxidation. The Mycobacterium whole cells oxidized the HMF to FDCA (60% yield) and hydroxymethyl furan carboxylic acid (HMFCA). A gene encoding a novel bacterial aryl alcohol oxidase, hereinafter MycspAAO, was identified in the genome and was cloned and expressed in Escherichia coli Bl21 (DE3). The purified MycspAAO displayed activity against several alcohols and aldehydes; 3,5 dimethoxy benzyl alcohol (veratryl alcohol) was the best substrate among those tested followed by HMF. 5-Hydroxymethylfurfural was converted to 5-formyl-2-furoic acid (FFCA) via diformyl furan (DFF) with optimal activity at pH 8 and 30-40°C. FDCA formation was observed during long reaction time with low HMF concentration. Mutagenesis of several amino acids shaping the active site and evaluation of the variants showed Y444F to have around 3-fold higher kcat /Km and ~1.7-fold lower Km with HMF.

Use of drugs not listed in the National List of Essential Medicines: Findings from a prescription analysis by the Indian Council of Medical Research-Rational Use of Medicines Centres Network in tertiary care hospitals across India.

BACKGROUND: The concept of listing essential medicines can lead to improved supply and access, more rational prescribing, and lower costs of drugs. However, these benefits hinge on the prescription of drugs from an Essential Medicines List (EML). Several studies have highlighted the problem of underutilization of EMLs by prescribers. Therefore, as part of prescription research by the Indian Council of Medical Research-Rational Use of Medicines Centres Network, we evaluated the extent of prescription of drugs not listed in the National List of Essential Medicines (NLEM). MATERIALS AND METHODS: Prescriptions of outpatients from participating centers were included after obtaining verbal/written informed consent as approved by the Ethics Committee, and evaluated for prescription of drugs from the NLEM 2015. RESULTS: Analysis of 4838 prescriptions from 13 tertiary health-care institutes revealed that 2677 (55.33%) prescriptions had at least one non-NLEM drug prescribed. In all, 5215 (31.12%) of the total 16,758 drugs prescribed were not in NLEM. Of these, 2722 (16.24%) were single drugs and 2493 (14.88%) were fixed-dose combinations (FDCs). These comprised 700 different drug products - 346 single drugs and 354 FDCs. The average number of non-NLEM drugs prescribed per prescription was 1.08, while the average number of all drugs prescribed was 3.35 per prescription. It was also found that some of the non-NLEM drugs prescribed had the potential to result in increased cost (for example, levocetirizine), increased adverse effects (dextromethorphan), and less effectiveness (losartan) when compared to their NLEM counterparts. Nonavailability of an essential drug (oral hydroxocobalamin) was another important finding of our study. CONCLUSION: This study highlights the extent and pattern of drugs prescribed from outside the NLEM at the tertiary health-care level and the need for training and enhanced awareness among prescribers for greater utilization of the NLEM.

A multicentre point prevalence survey (PPS) of antimicrobial use amongst admitted patients in tertiary care centres in India.

OBJECTIVES: Data from point prevalence surveys (PPSs) in India are scarce. Conducting PPSs is especially challenging in the absence of electronic medical records, a lack of dedicated resources and a high patient load in resource-poor settings. This multicentre survey was conducted to provide background data for planning and strengthening antimicrobial stewardship programmes across the country. METHODS: This inpatient PPS was conducted over 2 weeks in May 2019 simultaneously across five study centres in India. Data about patient characteristics, indications for antimicrobials use and details of each antimicrobial prescribed including supportive investigation reports were collected in predesigned forms. RESULTS: A total of 3473 admitted patients in wards and ICUs were covered across five study centres. Of these, 1747 (50.3%) patients were on antimicrobials, with 46.9% patients being on two or more antimicrobials. Out of the total antimicrobials prescribed, 40.2% of the antimicrobials were prescribed for community-acquired infection requiring hospitalization followed by surgical prophylaxis (32.6%). Third-generation cephalosporins and drugs from the 'Watch' category were prescribed most commonly. Only 22.8% of the antimicrobials were based on microbiology reports. CONCLUSIONS: The survey demonstrated a high use of antimicrobials in admitted patients with a considerable proportion of drugs from the 'Watch' category. The targets for interventions that emerged from the survey were: improving surgical prophylaxis, decreasing double anaerobic cover, initiating culture of sending cultures and de-escalation with targeted therapy.

Enhanced Protocatechuic Acid Production From Glucose Using Pseudomonas putida 3-Dehydroshikimate Dehydratase Expressed in a Phenylalanine-Overproducing Mutant of Escherichia coli.

Protocatechuic acid (PCA) is a strong antioxidant and is also a potential platform for polymer building blocks like vanillic acid, vanillin, muconic acid, and adipic acid. This report presents a study on PCA production from glucose via the shikimate pathway precursor 3-dehydroshikimate by heterologous expression of a gene encoding 3-dehydroshikimate dehydratase in Escherichia coli. The phenylalanine overproducing E. coli strain, engineered to relieve the allosteric inhibition of 3-deoxy-7-phosphoheptulonate synthase by the aromatic amino acids, was shown to give a higher yield of PCA than the unmodified strain under aerobic conditions. Highest PCA yield of 18 mol% per mol glucose and concentration of 4.2 g/L was obtained at a productivity of 0.079 g/L/h during cultivation in fed-batch mode using a feed of glucose and ammonium salt. Acetate was formed as a major side-product indicating a shift to catabolic metabolism as a result of feedback inhibition of the enzymes including 3-dehydroshikimate dehydratase by PCA when reaching a critical concentration. Indirect measurement of proton motive force by flow cytometry revealed no membrane damage of the cells by PCA, which was thus ruled out as a cause for affecting PCA formation.

Draft Genome Sequence of Limnospira sp. Strain BM01, Isolated from a Hypersaline Lake of the Momela Ecosystem in Tanzania.

The genus Limnospira includes cyanobacterial species used for industrial production of dietary supplements and nutraceutical agents. The metagenome-assembled genome of Limnospira sp. strain BM01 from Big Momela Lake, Tanzania, was 6,228,312 bp long with a GC content of 44.8% and carried 4,921 proteins and 52 RNA genes, including 6 rRNA genes.

Safety of hydroxychloroquine in healthcare workers for COVID-19 prophylaxis.

BACKGROUND & OBJECTIVES: Hydroxychloroquine (HCQ), reported to inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication in in vitro studies, has been recommended for prophylaxis of COVID-19 in healthcare workers (HCWs). The objective of this study was to assess short-term adverse events (AEs) of HCQ in HCWs. METHODS: This cross-sectional study among consenting HCWs taking prophylaxis and working in hospitals with COVID-19 patients used online forms to collect details of HCWs, comorbidities, prophylactic drugs used and AEs after the first dose of HCQ. Verification of dose and AEs was done by personal contact. Multivariate logistic regression analysis was done to determine the effect of age, gender and dose of HCQ on AE. RESULTS: Of the 1303 HCWs included, 98.4 per cent (n=1282) took HCQ and 66 per cent (n=861) took 800 mg as first day's dose. Among the 19.9 per cent (n=259) reporting AEs, 1.5 per cent (n=20) took treatment for AE, none were hospitalized and three discontinued HCQ. Gastrointestinal AEs were the most common (172, 13.2%), with less in older [odds ratio (OR) 0.56, 95% confidence interval (CI) 0.35-0.89], with more in females (OR 2.46, 95% CI 1.78-3.38) and in those taking a total dose of 800 mg on day one compared to a lower dose. Hypoglycaemia (1.1%, n=14), cardiovascular events (0.7%, n=9) and other AEs were minimal. INTERPRETATION & CONCLUSIONS: HCQ prophylaxis first dose was well tolerated among HCWs as evidenced by a low discontinuation. For adverse effects, a small number required treatment, and none required hospitalization. The study had limitations of convenience sampling and lack of laboratory and electrocardiography confirmation of AEs.

Metabolic potential of the moderate halophile Yangia sp. ND199 for co-production of polyhydroxyalkanoates and exopolysaccharides.

Yangia sp. ND199 is a moderately halophilic bacterium isolated from mangrove samples in Northern Vietnam, which was earlier reported to grow on several sugars and glycerol to accumulate poly(hydroxyalkanoates) (PHA). In this study, the potential of the bacterium for co-production of exopolysaccharides (EPS) and PHA was investigated. Genome sequence analysis of the closely related Yangia sp. CCB-M3 isolated from mangroves in Malaysia revealed genes encoding enzymes participating in different EPS biosynthetic pathways. The effects of various cultivation parameters on the production of EPS and PHA were studied. The highest level of EPS (288 mg/L) was achieved using sucrose and yeast extract with 5% NaCl and 120 mM phosphate salts but with modest PHA accumulation (32% of cell dry weight, 1.3 g/L). Growth on fructose yielded the highest PHA concentration (85% of CDW, 3.3 g/L) at 90 mM phosphate and higher molecular weight EPS at 251 mg/L yield at 120 mM phosphate concentration. Analysis of EPS showed a predominance of glucose, followed by fructose and galactose, and minor amounts of acidic sugars.

A multicentric knowledge-attitude-practice survey in the community about antimicrobial use and resistance in India.

BACKGROUND: To address the reasons for inappropriate use of antimicrobials, it is important to understand the knowledge, attitude and practices (KAP) of all pertinent stakeholders. This multicentric survey is aimed at understanding the KAP quotients of the community regarding antimicrobial use and antimicrobial resistance (AMR), as such information is lacking in India. METHODS: A cross-sectional survey was conducted by face-to-face interviews across five centers in India using a validated, field-tested questionnaire incorporating KAP domain questions. Scores were appropriately assigned to the questions. RESULTS: The mean (SD) age of the respondents was 35.2 (12.61) y and 62% had a graduate or higher level of education. The median (IQR) KAP scores were 10 (8-12), 5 (3-5) and 2 (2-3) out of a maximum of 18, 5 and 6, respectively. Higher educational and socioeconomic levels were associated with better attitude scores, but knowledge levels were comparable. Correlations between KAP scores were poor. CONCLUSIONS: This study reveals that laypeople have appropriate knowledge and attitude regarding antibiotic use and AMR to some degree but there are important lacunae and practices are often wanting. These issues need to be addressed in sustained public awareness and motivation campaigns to improve the rational use of antibiotics in India.

Polyhydroxyalkanoate production from rice straw hydrolysate obtained by alkaline pretreatment and enzymatic hydrolysis using Bacillus strains isolated from decomposing straw.

Rice straw is an important low-cost feedstock for bio-based economy. This report presents a study in which rice straw was used both as a source for isolation of bacteria producing the biodegradable polyester polyhydroxyalkanoate (PHA), as well as the carbon source for the production of the polymer by the isolated bacteria. Of the 100 bacterial isolates, seven were found to be positive for PHA production by Nile blue staining and were identified as Bacillus species by 16S rRNA gene sequence analysis. Three isolates showed 100% sequence identity to B. cereus, one to B. paranthracis, two with 99 and 100% identity to B. anthracis, while one was closely similar to B. thuringiensis. For use in PHA production, rice straw was subjected to mild alkaline pretreatment followed by enzymatic hydrolysis. Comparison of pretreatment by 2% sodium hydroxide, 2% calcium hydroxide and 20% aqueous ammonia, respectively, at different temperatures showed maximum weight loss with NaOH at 80 °C for 5 h, but ammonia for 15 h at 80 °C led to highest lignin removal of 63%. The ammonia-pretreated rice straw also led to highest release of total reducing sugar up to 92% on hydrolysis by a cocktail of cellulases and hemicellulases at 50 °C. Cultivation of the Bacillus isolates on the pretreated rice straw revealed highest PHA content of 59.3 and 46.4%, and PHA concentration of 2.96 and 2.51 g/L by Bacillus cereus VK92 and VK98, respectively.

Clean Production of Levulinic Acid from Fructose and Glucose in Salt Water by Heterogeneous Catalytic Dehydration.

Levulinic acid (LA) is considered to be one of the promising organic bio-platform chemicals and intermediates for the synthesis of fuels, chemicals, and polymers. In the present study, heterogeneous catalytic dehydration of hexose sugars, fructose and glucose, using a strong cation exchange resin (hydrogen form) as an acid catalyst, was performed to produce LA in an aqueous medium. The effect of salts such as NaCl, KCl, CaCl2, Na2CO3, and Na2SO4 in the medium on the rate of sugar conversion and LA yield was evaluated. Under optimum reaction conditions, 10% (w/w) fructose was dehydrated to LA (with 74.6% yield) in 10% (w/w) NaCl aqueous solution in 24 h at 110 °C using the catalyst at 30% (w/w sugar). Even 10% (w/w) glucose monohydrate was directly dehydrated to LA (with 70.7% yield) under similar conditions but at 145 °C. This study shows that the salts enhance the rate of catalytic dehydration in the order of Cl- > CO3 2- > SO4 2-. Thus, the combination of high sugar concentration and heterogeneous catalysis in an aqueous system under relatively mild conditions could provide a high-yielding and sustainable process for bio-based LA production.

Omics for Bioprospecting and Drug Discovery from Bacteria and Microalgae.

"Omics" represent a combinatorial approach to high-throughput analysis of biological entities for various purposes. It broadly encompasses genomics, transcriptomics, proteomics, lipidomics, and metabolomics. Bacteria and microalgae exhibit a wide range of genetic, biochemical and concomitantly, physiological variations owing to their exposure to biotic and abiotic dynamics in their ecosystem conditions. Consequently, optimal conditions for adequate growth and production of useful bacterial or microalgal metabolites are critically unpredictable. Traditional methods employ microbe isolation and 'blind'-culture optimization with numerous chemical analyses making the bioprospecting process laborious, strenuous, and costly. Advances in the next generation sequencing (NGS) technologies have offered a platform for the pan-genomic analysis of microbes from community and strain downstream to the gene level. Changing conditions in nature or laboratory accompany epigenetic modulation, variation in gene expression, and subsequent biochemical profiles defining an organism's inherent metabolic repertoire. Proteome and metabolome analysis could further our understanding of the molecular and biochemical attributes of the microbes under research. This review provides an overview of recent studies that have employed omics as a robust, broad-spectrum approach for screening bacteria and microalgae to exploit their potential as sources of drug leads by focusing on their genomes, secondary metabolite biosynthetic pathway genes, transcriptomes, and metabolomes. We also highlight how recent studies have combined molecular biology with analytical chemistry methods, which further underscore the need for advances in bioinformatics and chemoinformatics as vital instruments in the discovery of novel bacterial and microalgal strains as well as new drug leads.

Exploring the Enzymatic and Antibacterial Activities of Novel Mycobacteriophage Lysin B Enzymes.

Mycobacteriophages possess different sets of lytic enzymes for disruption of the complex cell envelope of the mycobacteria host cells and release of the viral progeny. Lysin B (LysB) enzymes are mycolylarabinogalactan esterases that cleave the ester bond between the arabinogalactan and mycolic acids in the mycolylarabinogalactan-peptidoglycan (mAGP) complex in the cell envelope of mycobacteria. In the present study, four LysB enzymes were produced recombinantly and characterized with respect to their enzymatic and antibacterial activities. Examination of the kinetic parameters for the hydrolysis of para-nitrophenyl ester substrates, shows LysB-His6 enzymes to be active against a range of substrates (C4-C16), with a catalytic preference towards p-nitrophenyl laurate (C12). With p-nitrophenyl butyrate as substrate, LysB-His6 enzymes showed highest activity at 37 °C. LysB-His6 enzymes also hydrolyzed different Tween substrates with highest activity against Tween 20 and 80. Metal ions like Ca2+ and Mn2+ enhanced the enzymatic activity of LysB-His6 enzymes, while transition metal ions like Zn2+ and Cu2+ inhibited the enzymatic activity. The mycolylarabinogalactan esterase activity of LysB-His6 enzymes against mAGP complex was confirmed by LC-MS. LysB-His6 enzymes showed marginal antibacterial activity when tested alone against Mycobacterium smegmatis, however a synergetic activity was noticed when combined with outer membrane permealizers. These results confirm that LysB enzymes are lipolytic enzymes with potential application as antimycobacterials.