Extraction of protein from food waste: An overview of current status and opportunities.

The chief intent of this review is to explain the different extraction techniques and efficiencies for the recovery of protein from food waste (FW) sources. Although FW is not a new concept, increasing concerns about chronic hunger, nutritional deficiency, food security, and sustainability have intensified attention on alternative and sustainable sources of protein for food and feed. Initiatives to extract and utilize protein from FW on a commercial scale have been undertaken, mainly in the developed countries, but they remain largely underutilized and generally suited for low-quality products. The current analysis reveals the extraction of protein from FW is a many-sided (complex) issue, and that identifies for a stronger and extensive integration of diverse extraction perspectives, focusing on nutritional quality, yield, and functionality of the isolated protein as a valued recycled ingredient.

Comparative genomic analysis of ten clinical Streptococcus pneumoniae collected from a Malaysian hospital reveal 31 new unique drug-resistant SNPs using whole genome sequencing.

BACKGROUND: Streptococcus pneumoniae or pneumococcus is a leading cause of morbidity and mortality worldwide, specifically in relation to community-acquired pneumonia. Due to the overuse of antibiotics, S. pneumoniae has developed a high degree of resistance to a wide range of antibacterial drugs. METHODS: In this study, whole genome sequencing (WGS) was performed for 10 clinical strains of S. pneumoniae with different levels of sensitivity to standard antibiotics. The main objective was to investigate genetic changes associated with antibiotic resistance in S. pneumoniae. RESULTS: Our results showed that resistant isolates contain a higher number of non-synonymous single nucleotide polymorphisms (SNPs) as compared to susceptible isolates. We were able to identify SNPs that alter a single amino acid in many genes involved in virulence and capsular polysaccharide synthesis. In addition, 90 SNPs were only presented in the resistant isolates, and 31 SNPs were unique and had not been previously reported, suggesting that these unique SNPs could play a key role in altering the level of resistance to different antibiotics. CONCLUSION: Whole genome sequencing is a powerful tool for comparing the full genome of multiple isolates, especially those closely related, and for analysing the variations found within antibiotic resistance genes that lead to differences in antibiotic sensitivity. We were able to identify specific mutations within virulence genes related to resistant isolates. These findings could provide insights into understanding the role of single nucleotide mutants in conferring drug resistance.

Intracellular Targeting Mechanisms by Antimicrobial Peptides.

Antimicrobial peptides (AMPs) are expressed in various living organisms as first-line host defenses against potential harmful encounters in their surroundings. AMPs are short polycationic peptides exhibiting various antimicrobial activities. The principal antibacterial activity is attributed to the membrane-lytic mechanism which directly interferes with the integrity of the bacterial cell membrane and cell wall. In addition, a number of AMPs form a transmembrane channel in the membrane by self-aggregation or polymerization, leading to cytoplasm leakage and cell death. However, an increasing body of evidence has demonstrated that AMPs are able to exert intracellular inhibitory activities as the primary or supportive mechanisms to achieve efficient killing. In this review, we focus on the major intracellular targeting activities reported in AMPs, which include nucleic acids and protein biosynthesis and protein-folding, protease, cell division, cell wall biosynthesis, and lipopolysaccharide inhibition. These multifunctional AMPs could serve as the potential lead peptides for the future development of novel antibacterial agents with improved therapeutic profiles.

Impact of cavitation on the structure and functional quality of extracted protein from food sources - An overview.

Increasing protein demands directly require additional resources to those presently and recurrently available. Emerging green technologies have witnessed an escalating interest in "Cavitation Processing" (CP) to ensure a non-invasive, non-ionizing and non-polluting extraction. The main intent of this review is to present an integrated summary of cavitation extraction methods specifically applied to food protein sources. Along with a comparative assessment carried out for each type of cavitation model, protein extraction yield and implications on the extracted protein's structural and functional properties. The basic principle of cavitation is due to the pressure shift in the liquid flow within milliseconds. Hence, cavitation emerges similar to boiling; however, unlike boiling (temperature change), cavitation occurs due to pressure change. Characterization and classification of sample type is also a prime candidate when considering the applications of cavitation models in food processing. Generally, acoustic and hydrodynamic cavitation is applied in food applications including extraction, brewing, microbial cell disruption, dairy processing, emulsification, fermentation, waste processing, crystallisation, mass transfer and production of bioactive peptides. Micro structural studies indicate that shear stress causes disintegration of hydrogen bonds and Van der Waals interactions result in the unfolding of the protein's secondary and/or tertiary structures. A change in the structure is not targeted but rather holistic and affects the physicochemical, functional, and nutritional properties. Cavitation assisted extraction of protein is typically studied at a laboratory scale. This highlights limitations against the application at an industrial scale to obtain potential commercial gains.

Green solvent processing: Effect of type of solvent on extraction and quality of protein from dairy and non-dairy expired milk products.

The present study was designed to study the effect of green solvent processing in two folds, (i) to extract valuable protein from dairy and non-dairy expired milk products and (ii) to compare extraction efficiency and quality of extracted protein using conventional (CS) and green solvents (GS). Ethyl acetate, ethanol, isopropanol, n-heptane and cyclopentyl methyl ether (CPME) were selected as the GS for the possible substitution of hexane and ethyl ether. For each respective solvent, protein recovery, structural and functional modifications were studied. Protein yield was extracted most effectively by GS n-heptane in dairy milk (5.33 ± 0.01%) with a protein purity of 39.73 ± 0.90%. Non-dairy milk and product had similar protein yield when treated with CS and GS. Total mean of extraction efficiency, structural and functional modifications across all samples showed GS solvents were statistically more effective than CS.

Serotype distribution of invasive, non-invasive and carried Streptococcus pneumoniae in Malaysia: a meta-analysis.

BACKGROUND: Pneumococcal pneumonia is the leading cause of under-five mortality globally. The surveillance of pneumococcal serotypes is therefore vital for informing pneumococcal vaccination policy and programmes. Pneumococcal conjugate vaccines (PCVs) have been available as an option in the private healthcare setting and beginning December 2020, PCV10 was incorporated as part of routine national immunisation programme (NIP) in Malaysia. We searched existing literature on pneumococcal serotype distribution across Malaysia to provide an overall view of this distribution before the implementation of PCV10. METHODS: Online databases (PubMed, Ovid MEDLINE and Scopus), reference lists of articles identified, and grey literature (Malaysian Ministry of Health website, WHO website) were systematically searched for relevant literature on pneumococcal serotype distribution across Malaysia up to 10th November 2020. No lower date limit was set to maximise the number of target reports returned. Results of serotypes were split by age categories, including ≤5 years, > 5 years and unreported for those that did not specify. RESULTS: The search returned 18 relevant results, with a total of 2040 isolates. The most common serotypes across all disease types were 19F (n = 313, 15.3% [95%CI: 13.8-17.0]), 23F (n = 166, 8.1% [95%CI: 7.0-9.4]), 14 (n = 166, 8.1% [95%CI: 7.0-9.4]), 6B (n = 163, 8.0% [95%CI: 6.9-9.2]) and 19A (n = 138, 6.8% [95%CI: 5.8-7.9]). CONCLUSION: Four of the most common serotypes across all isolate sources in Malaysia are covered by PCV10, while PCV13 provides greater serotype coverage in comparison to PCV10. There is still a need for surveillance studies, particularly those investigating serotypes in children under 5 years of age, to monitor vaccine effectiveness and pneumococcal population dynamic following implementation of PCV10 into routine immunisation.

Sustainable utilization of biowaste compost for renewable energy and soil amendments.

Acceleration of urbanization and industrialization has resulted in the drastic rise of waste generation with majority of them being biowaste. This constitutes a global challenge since conventional waste management methods (i.e., landfills) present environmental issues including greenhouse gases emissions, leachate formation and toxins release. A sustainable and effective approach to treat biowaste is through composting. Various aspects of composting such as compost quality, composting systems and compost pelletization are summarized in this paper. Common application of compost as fertilizer or soil amendment is presented with focus on the low adoption level of organic waste compost in reality. Rarely known, compost which is easily combustible can be utilized to generate electricity. With the analysis on critical approaches, this review aims to provide a comprehensive study on energy content of compost pellets, which has never been reviewed before. Environmental impacts and future prospects are also highlighted to provide further insights on application of this technology to close the loop of circular bioeconomy.

Antimicrobial peptides from different plant sources: Isolation, characterisation, and purification.

Antimicrobial peptides (AMPs), the self-defence products of organisms, are extensively distributed in plants. They can be classified into several groups, including thionins, defensins, snakins, lipid transfer proteins, glycine-rich proteins, cyclotides and hevein-type proteins. AMPs can be extracted and isolated from different plants and plant organs such as stems, roots, seeds, flowers and leaves. They perform various physiological defensive mechanisms to eliminate viruses, bacteria, fungi and parasites, and so could be used as therapeutic and preservative agents. Research on AMPs has sought to obtain more detailed and reliable information regarding the selection of suitable plant sources and the use of appropriate isolation and purification techniques, as well as examining the mode of action of these peptides. Well-established AMP purification techniques currently used include salt precipitation methods, absorption-desorption, a combination of ion-exchange and reversed-phase C18 solid phase extraction, reversed-phase high-performance liquid chromatography (RP-HPLC), and the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) method. Beyond these traditional methods, this review aims to highlight new and different approaches to the selection, characterisation, isolation, purification, mode of action and bioactivity assessment of a range of AMPs collected from plant sources. The information gathered will be helpful in the search for novel AMPs distributed in the plant kingdom, as well as providing future directions for the further investigation of AMPs for possible use on humans.

How far have we reached in development of effective influenza vaccine?

Despite of ongoing research programs and numerous clinical trials, seasonal influenza epidemics remain a major concern globally. Vaccination remains the most effective method to prevent influenza infection. However, current flu vaccines have several limitations, including limited vaccine capacity, long production times, inconsistence efficacy in certain populations, and lack of a "universal" solution. Different next-generation approaches such as cell line-based culture, reverse genetics, and virus expression technology are currently under development to address the aforementioned challenges in conventional vaccine manufacture pipeline. Such approaches hope for safe and scalable production, induce broad-spectrum immunity, create premade libraries of vaccine strains, and target nonvariable regions of antigenic proteins for "universal" vaccination. Here, we discuss the process and challenges of the current influenza vaccine platform as well as new approaches that are being investigated. These developments indicate that an exciting future lies ahead in the influenza vaccine field.

Extractive disruption process integration using ultrasonication and an aqueous two-phase system for protein recovery from Chlorella sorokiniana.

Microalgae emerge as the most promising protein sources for aquaculture industry. However, the commercial proteins production at low cost remains a challenge. The process of harnessing microalgal proteins involves several steps such as cell disruption, isolation and extraction. The discrete processes are generally complicated, time-consuming and costly. To date, the notion of integrating microalgal cell disruption and proteins recovery process into one step is yet to explore. Hence, this study aimed to investigate the feasibility of applying methanol/potassium ATPS in the integrated process for proteins recovery from Chlorella sorokiniana. Parameters such as salt types, salt concentrations, methanol concentrations, NaCl addition were optimized. The possibility of upscaling and the effectiveness of recycling the phase components were also studied. The results showed that ATPS formed by 30% (w/w) K3PO4 and 20% (w/w) methanol with 3% (w/w) NaCl addition was optimum for proteins recovery. In this system, the partition coefficient and yield were 7.28 and 84.23%, respectively. There were no significant differences in the partition coefficient and yield when the integrated process was upscaled to 100-fold. The recovered phase components can still be recycled effectively at fifth cycle. In conclusions, this method is simple, rapid, environmental friendly and could be implemented at large scale.

Phytosterols isolated from Clinacanthus nutans induce immunosuppressive activity in murine cells.

Clinacanthus nutans (Burm. f.) Lindau is a traditional medicinal plant belonging to the Acanthaceae family. Its therapeutic potentials have been increasingly documented particularly the antiviral activity against Herpes Simplex Virus (HSV), anti-cancer, anti-oxidant, anti-inflammatory and immunomodulatory activities. However, majority of these studies used crude or fractionated extracts and not much is known about individual compounds from these extracts and their biological activities. In the present study, we have isolated four compounds (CN1, CN2, CN3 and CN4) from the hexane fractions of C. nutans leaves. Using NMR spectroscopic analysis, these compounds were identified to be shaftoside (CN1), stigmasterol (CN2), ß-sitosterol (CN3) and a triterpenoid lupeol (CN4). To determine the immunosuppressive potential of these compounds, their effects on mitogens induced T and B lymphocyte proliferation and the secretion of helper T cell cytokines were examined. Among the four compounds, stigmasterol (CN2) and ß-sitosterol (CN3) were shown to readily inhibit T cell proliferation mediated by Concanavalin A (ConA). However, only ß-sitosterol (CN3) and not stigmasterol (CN2) blocks the secretion of T helper 2 (Th2) cytokines (IL-4 and IL-10). Both compounds have no effect on the secretion of Th1 cytokines (IL-2 and IFN-γ), suggesting that ß-sitosterol treatment selectively suppresses Th2 activity and promotes a Th1 bias. CN3 was also found to significantly reduce the proliferation of both T helper cells (CD4+CD25+) and cytotoxic T cells (CD8+CD25+) following T cell activation induced by ConA. These results suggested that phytosterols isolated from C. nutans possess immunomodulatory effects with potential development as immunotherapeutics.

Next generation sequencing reveals the antibiotic resistant variants in the genome of Pseudomonas aeruginosa.

Rapid progress in next generation sequencing and allied computational tools have aided in identification of single nucleotide variants in genomes of several organisms. In the present study, we have investigated single nucleotide polymorphism (SNP) in ten multi-antibiotic resistant Pseudomonas aeruginosa clinical isolates. All the draft genomes were submitted to Rapid Annotations using Subsystems Technology (RAST) web server and the predicted protein sequences were used for comparison. Non-synonymous single nucleotide polymorphism (nsSNP) found in the clinical isolates compared to the reference genome (PAO1), and the comparison of nsSNPs between antibiotic resistant and susceptible clinical isolates revealed insights into the genome variation. These nsSNPs identified in the multi-drug resistant clinical isolates were found to be altering a single amino acid in several antibiotic resistant genes. We found mutations in genes encoding efflux pump systems, cell wall, DNA replication and genes involved in repair mechanism. In addition, nucleotide deletions in the genome and mutations leading to generation of stop codons were also observed in the antibiotic resistant clinical isolates. Next generation sequencing is a powerful tool to compare the whole genomes and analyse the single base pair variations found within the antibiotic resistant genes. We identified specific mutations within antibiotic resistant genes compared to the susceptible strain of the same bacterial species and these findings may provide insights to understand the role of single nucleotide variants in antibiotic resistance.

Transcriptome analysis of Streptococcus pneumoniae treated with the designed antimicrobial peptides, DM3.

In our previous studies, we generated a short 13 amino acid antimicrobial peptide (AMP), DM3, showing potent antipneumococcal activity in vitro and in vivo. Here we analyse the underlying mechanisms of action using Next-Generation transcriptome sequencing of penicillin (PEN)-resistant and PEN-susceptible pneumococci treated with DM3, PEN, and combination of DM3 and PEN (DM3PEN). DM3 induced differential expression in cell wall and cell membrane structural and transmembrane processes. Notably, DM3 altered the expression of competence-induction pathways by upregulating CelA, CelB, and CglA while downregulating Ccs16, ComF, and Ccs4 proteins. Capsular polysaccharide subunits were downregulated in DM3-treated cells, however, it was upregulated in PEN- and DM3PEN-treated groups. Additionally, DM3 altered the amino acids biosynthesis pathways, particularly targeting ribosomal rRNA subunits. Downregulation of cationic AMPs resistance pathway suggests that DM3 treatment could autoenhance pneumococci susceptibility to DM3. Gene enrichment analysis showed that unlike PEN and DM3PEN, DM3 treatment exerted no effect on DNA-binding RNA polymerase activity but observed downregulation of RpoD and RNA polymerase sigma factor. In contrast to DM3, DM3PEN altered the regulation of multiple purine/pyrimidine biosynthesis and metabolic pathways. Future studies based on in vitro experiments are proposed to investigate the key pathways leading to pneumococcal cell death caused by DM3.

In vitro properties of designed antimicrobial peptides that exhibit potent antipneumococcal activity and produces synergism in combination with penicillin.

Antimicrobial peptides (AMPs) represent a promising class of novel antimicrobial agents owing to their potent antimicrobial activity. In this study, two lead peptides from unrelated classes of AMPs were systematically hybridized into a series of five hybrid peptides (DM1-DM5) with conserved N- and C-termini. This approach allows sequence bridging of two highly dissimilar AMPs and enables sequence-activity relationship be detailed down to single amino acid level. Presence of specific amino acids and physicochemical properties were used to describe the antipneumococcal activity of these hybrids. Results obtained suggested that cell wall and/or membrane targeting could be the principal mechanism exerted by the hybrids leading to microbial cell killing. Moreover, the pneumocidal rate was greater than penicillin (PEN). Combination treatment with both DMs and PEN produced synergism. The hybrids were also broad spectrum against multiple common clinical bacteria. Sequence analysis showed that presence of specific residues has a major role in affecting the antimicrobial and cell toxicity of the hybrids than physicochemical properties. Future studies should continue to investigate the mechanisms of actions, in vivo therapeutic potential, and improve rational peptide design based on the current strategy.

In vivo efficacy and molecular docking of designed peptide that exhibits potent antipneumococcal activity and synergises in combination with penicillin.

We have previously designed a series of antimicrobial peptides (AMPs) and in the current study, the in vivo therapeutic efficacy and toxicity were investigated. Among all the peptides, DM3 conferred protection to a substantial proportion of the lethally infected mice caused by a strain of penicillin-resistant Streptococcus pneumoniae. Synergism was reported and therapeutic efficacy was significantly enhanced when DM3 was formulated in combination with penicillin (PEN). No toxicity was observed in mice receiving these treatments. The in silico molecular docking study results showed that, DM3 has a strong affinity towards three protein targets; autolysin and pneumococcal surface protein A (pspA). Thus AMPs could serve as supporting therapeutics in combination with conventional antibiotics to enhance treatment outcome.

Activity of Novel Synthetic Peptides against Candida albicans.

Candida spp. are the most common causes of fungal infections worldwide. Among the Candida species, Candida albicans remains the predominant species that causes invasive candidiasis in most countries. In this study, we used two peptides, KABT-AMP and uperin 3.6 as templates to develop novel antifungal peptides. Their anticandidal activity was assessed using a combination of MIC, time-killing assay and biofilm reduction assay. Hybrid peptides, KU2 and KU3 containing a mixed backbone of KABT-AMP and Uperin 3.6 demonstrated the most potent anticandidal activity with MIC values ranging from 8-16 mg/L. The number of Trp residues and the amphipathic structure of peptides probably enhanced the anticandidal activity of peptides. Increasing the cationicity of the uperin 3.6 analogues resulted in reduced MIC from the range of 64-128 mg/L to 16-64 mg/L and this was also correlated with the antibiofilm activity and killing kinetics of the peptides. Peptides showed synergistic effects when used in combination with conventional antifungals. Peptides demonstrated low haemolytic activity but significant toxicity on two normal human epithelial cell lines. This study provides us with a better understanding on the structure-activity relationship and the balance between cationicity and hydrophobicity of the peptides although the therapeutic application of the peptides is limited.

Antimicrobial Activity of Novel Synthetic Peptides Derived from Indolicidin and Ranalexin against Streptococcus pneumoniae.

Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics in order to defeat multidrug-resistant bacteria such as Streptococcus pneumoniae. In this study, thirteen antimicrobial peptides were designed based on two natural peptides indolicidin and ranalexin. Our results revealed that four hybrid peptides RN7-IN10, RN7-IN9, RN7-IN8, and RN7-IN6 possess potent antibacterial activity against 30 pneumococcal clinical isolates (MIC 7.81-15.62µg/ml). These four hybrid peptides also showed broad spectrum antibacterial activity (7.81µg/ml) against S. aureus, methicillin resistant S. aureus (MRSA), and E. coli. Furthermore, the time killing assay results showed that the hybrid peptides were able to eliminate S. pneumoniae within less than one hour which is faster than the standard drugs erythromycin and ceftriaxone. The cytotoxic effects of peptides were tested against human erythrocytes, WRL-68 normal liver cell line, and NL-20 normal lung cell line. The results revealed that none of the thirteen peptides have cytotoxic or hemolytic effects at their MIC values. The in silico molecular docking study was carried out to investigate the binding properties of peptides with three pneumococcal virulent targets by Autodock Vina. RN7IN6 showed a strong affinity to target proteins; autolysin, pneumolysin, and pneumococcal surface protein A (PspA) based on rigid docking studies. Our results suggest that the hybrid peptides could be suitable candidates for antibacterial drug development.

The epidemiology of pneumococcal carriage and infections in Malaysia.

In Malaysia, various aspects of the epidemiology of pneumococcal carriage and disease remain largely unclear due to the lack of supporting data. Although a number of relevant studies have been documented, their individual discrete findings are not sufficient to inform experts on pneumococcal epidemiology at a national level. Therefore, in this review we aim to bring together and systematically evaluate the key information regarding pneumococcal disease epidemiology in Malaysia and provide a comprehensive overview of the data. Major aspects discussed include pneumococcal carriage, disease incidence and prevalence, age factors, invasiveness of pneumococci, serotypes, molecular epidemiology and antibiotic susceptibility. Penicillin resistance is increasingly prevalent and studies suggest that the majority of pneumococcal serotypes causing pneumococcal disease in Malaysia are covered by currently available conjugate vaccines. Continued surveillance is needed to provide a better understanding of pneumococcal epidemiology in Malaysia.

Capsular serotype and antibiotic resistance of Streptococcus pneumoniae isolates in Malaysia.

BACKGROUND: Streptococcus pneumoniae is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, that has since become a major public health concern. In this study, the serotypes distribution of pneumococcal isolates was investigated to predict the efficacy of the 7-valent pneumococcal conjugate vaccine (PCV7) among the Malaysian populations. METHODOLOGY/PRINCIPAL FINDINGS: A total of 151 clinical isolates were serotyped using multiplex PCR assays. Out of them, there were 21.2% penicillin-resistant, 29.1% penicillin-intermediate, and 49.7% penicillin-susceptible S. pneumoniae strains. Serotypes detected among the Malaysian isolates were 1, 3, 10A, 11A/11D, 12F/12A, 14, 15A, 15B/15C, 16F, 18C/18B/18A/18F, 19A, 19F, 23F, 35B, 35F/47F, 6A/6B, 7C/7B/40, 7F/7A, 9V/9A, and 34. Serotype 19F and 23F were the two most prevalent serotypes detected. Serotypes are highly associated with invasiveness of isolates (p = 0.001) and penicillin susceptibility (p<0.001). Serotype 19F was observed to have increased resistance against penicillin while serotype 19A has high invasive tendency. Age of patients was an important factor underlying the pneumococcal serotypes (p = 0.03) and clinical sites of infections (p<0.001). High prevalence of pneumococcal isolates were detected among children <5 years old at nasopharyngeal sites while elderly adults ≥60 years old were at increased risk for pneumococcal bacteremia. CONCLUSION/SIGNIFICANCE: Current study revealed that a number of serotypes, especially those associated with high penicillin resistance, have been formulated in the PCV7. Therefore, the protections expected from the routine use of PCV7 would be encouraging for the Malaysian. However, it is not possible to predict serotypes that might become predominant in the future and hence continued surveillance of circulating serotypes will be needed.