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Improvement of combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase and maltogenic amylase by functionalization of cross-linker for maltooligosaccharides synthesis

Yip YS, Jaafar NR, Rahman RA, Puspaningsih NNT, Jailani N, Illias RM

Int J Biol Macromol, 2024 Jul;273(Pt 2):133241.
PMID: 38897508 DOI: 10.1016/j.ijbiomac.2024.133241

Combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase (CGTase) and maltogenic amylase (Mag1) from Bacillus lehensis G1 (Combi-CLEAs-CM) were successfully developed to synthesis maltooligosaccharides (MOS). Yet, the poor cross-linking performance between chitosan (cross-linker) and enzymes resulting low activity recovery and catalytic efficiency. In this study, we proposed the functionalization of cross-linkers with the integration of computational analysis to study the influences of different functional group on cross-linkers in combi-CLEAs development. From in-silico analysis, O-carboxymethyl chitosan (OCMCS) with the highest binding affinity toward both enzymes was chosen and showed alignment with the experimental result, in which OCMCS was synthesized as cross-linker to develop improved activity recovery of Combi-CLEAs-CM-ocmcs (74 %). The thermal stability and deactivation energy (205.86 kJ/mol) of Combi-CLEAs-CM-ocmcs were found to be higher than Combi-CLEAs-CM (192.59 kJ/mol). The introduction of longer side chain of carboxymethyl group led to a more flexible structure of Combi-CLEAs-CM-ocmcs. This alteration significantly reduced the Km value of Combi-CLEAs-CM-ocmcs by about 3.64-fold and resulted in a greater Kcat/Km (3.63-fold higher) as compared to Combi-CLEAs-CM. Moreover, Combi-CLEAs-CM-ocmcs improved the reusability with retained >50 % of activity while Combi-CLEAs-CM only 36.18 % after five cycles. Finally, maximum MOS production (777.46 mg/g) was obtained by Combi-CLEAs-CM-ocmcs after optimization using response surface methodology.
Combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase and maltogenic amylase from Bacillus lehensis G1 for maltooligosaccharides synthesis

Yip YS, Manas NHA, Jaafar NR, Rahman RA, Puspaningsih NNT, Illias RM

Int J Biol Macromol, 2023 Jul 01;242(Pt 1):124675.
PMID: 37127056 DOI: 10.1016/j.ijbiomac.2023.124675

Maltooligosaccharides (MOS) are functional oligosaccharides that can be synthesized through enzymatic cascade reaction between cyclodextrin glucanotransferase (CGTase) and maltogenic amylase (Mag1) from Bacillus lehensis G1. To address the problems of low operational stability and non-reusability of free enzymes, both enzymes were co-immobilized as combined cross-linked enzyme aggregates (Combi-CLEAs-CM) with incorporation of bovine serum albumin (BSA) and Tween 80 (Combi-CLEAs-CM-add). Combi-CLEAs-CM and Combi-CLEAs-CM-add showed activity recoveries of 54.12 % and 69.44 %, respectively after optimization. Combi-CLEAs-CM-add showed higher thermal stability at higher temperatures (40 °C) with longer half-life (46.20 min) as compared to those of free enzymes (36.67 min) and Combi-CLEAs-CM (41.51 min). Both combi-CLEAs also exhibited higher pH stability over pH 5 to pH 9, and displayed excellent reusability with >50 % of initial activity retained after four cycles. The reduction in Km value of about 22.80 % and 1.76-fold increase in starch hydrolysis in comparison to Combi-CLEAs-CM attested the improvement of enzyme-substrate interaction by Tween 80 and pores formation by BSA in Combi-CLEAs-CM-add. The improved product specificity of Combi-CLEAs-CM-add also produced the highest yield of MOS (492 mg/g) after 3 h. Therefore, Combi-CLEAs-CM-add with ease of preparation, excellent reusability and high operational stability is believed to be highly efficacious biocatalyst for MOS production.
Innovative biocatalyst synthesis of pectinolytic enzymes by cross-linking strategy: Potentially immobilised pectinases for the production of pectic-oligosaccharides from pectin

Abd Rahman NH, Rahman RA, Rahmat Z, Jaafar NR, Puspaningsih NNT, Illias RM

Int J Biol Macromol, 2024 Jan;256(Pt 1):128260.
PMID: 38000618 DOI: 10.1016/j.ijbiomac.2023.128260

Pectinases are outstanding multienzymes, which have the potential to produce new emerging pectic-oligosaccharides (POS) via enzymatic hydrolysis of pectin. However, free pectinase is unable to undergo repeated reaction for the production of POS. This study proposed a sustainable biocatalyst of pectinases known as cross-linked pectinase aggregates (CLPA). Pectinase from Aspergillus aculeatus was successfully precipitated using 2 mg/mL pectinase and 60 % acetone for 20 min at 20 °C, which remained 36.3 % of its initial activity. The prepared CLPA showed the highest activity recovery (85.0 %), under the optimised conditions (0.3 % (v/v) starch and glutaraldehyde mixture (St/Ga), 1.5: 1 of St/Ga, 25 °C, 1.5 h). Furthermore, pectin-degrading enzymes from various sources were used to produce different CLPA. The alteration of pectinase secondary structure gave high stability in acidic condition (pH 4), thermostability, deactivation energy and half-life, and improved storage stability at 4 °C for 30 days. Similarly to their free counterpart, the CLPA exhibited comparable enzymatic reaction kinetics and could be reused eight times with approximately 20 % of its initial activity. The developed CLPA does not only efficaciously produced POS from pectin as their free form, but also exhibited better operational stability and reusability, making it more suitable for POS production.
Health and wellbeing of staff working at higher education institutions globally during the post-COVID-19 pandemic period: evidence from a cross-sectional study

Rahman MA, Das P, Lam L, Alif SM, Sultana F, Salehin M, et al.

BMC Public Health, 2024 Jul 11;24(1):1848.
PMID: 38992680 DOI: 10.1186/s12889-024-19365-1

BACKGROUND: The ongoing global crisis of Higher Education (HE) institutions during the post-COVID-19 pandemic period has increased the likelihood of enduring psychological stressors for staff. This study aimed to identify factors associated with job insecurity, burnout, psychological distress and coping amongst staff working at HE institutions globally.
METHODS: An anonymous cross-sectional study was conducted in 2023 with staff at HE institutions across 16 countries. Job insecurity was measured using the Job Insecurity Scale (JIS), burnout using the Perceived Burnout measure question, psychological distress using the Kessler Psychological Distress Scale (K10), and coping using the Brief Resilient Coping Scale. Multivariable logistic regression with a stepwise variable selection method was used to identify associations.
RESULTS: A total of 2,353 staff participated; the mean age (± SD) was 43(± 10) years and 61% were females. Most staff (85%) did not feel job insecurity, one-third (29%) perceived burnout in their jobs, more than two-thirds (73%) experienced moderate to very high levels of psychological distress, and more than half (58%) exhibited medium to high resilient coping. Perceived job insecurity was associated with staff working part-time [Adjusted Odds Ratio 1.53 (95% Confidence Intervals 1.15-2.02)], having an academic appointment [2.45 (1.78-3.27)], having multiple co-morbidities [1.86 (1.41-2.48)], perceived burnout [1.99 (1.54-2.56)] and moderate to very high level of psychological distress [1.68 (1.18-2.39)]. Perceived burnout was associated with being female [1.35 (1.12-1.63)], having multiple co-morbidities [1.53 (1.20-1.97)], perceived job insecurity [1.99 (1.55-2.57)], and moderate to very high levels of psychological distress [3.23 (2.42-4.30)]. Staff with multiple co-morbidities [1.46 (1.11-1.92)], mental health issues [2.73 (1.79-4.15)], perceived job insecurity [1.61 (1.13-2.30)], and perceived burnout [3.22 (2.41-4.31)] were associated with moderate to very high levels of psychological distress. Staff who perceived their mental health as good to excellent [3.36 (2.69-4.19)] were more likely to have medium to high resilient coping.
CONCLUSIONS: Factors identified in this study should be considered in reviewing and updating current support strategies for staff at HE institutions across all countries to reduce stress and burnout and improve wellbeing.