Bacterial biofilm growth and perturbation by serine protease from Bacillus sp

In nature, bacteria are ubiquitous and can be categorized as beneficial or harmless to humans, but most bacteria have one thing in common which is their ability to produce biofilm. Biofilm is encased within an extracellular polymeric substance (EPS) which provides resistance against antimicrobial agents. Protease enzymes have the potential to degrade or promote the growth of bacterial biofilms. In this study, the effects of a recombinant intracellular serine protease from Bacillus sp. (SPB) on biofilms from Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa were analyzed. SPB was purified using HisTrap HP column and concentrated using Amicon 30 ultra-centrifugal filter. SPB was added with varying enzyme activity and assay incubation period after biofilms were formed in 96-well plates. SPB was observed to have contrasting effects on different bacterial biofilms, where biofilm degradations were observed for both 7-day-old A. baumannii (37.26%) and S. aureus (71.51%) biofilms. Meanwhile, SPB promoted growth of P. aeruginosa biofilm up to 176.32%. Compatibility between protein components in S. aureus biofilm with SPB as well as a simpler membrane structure morphology led to higher biofilm degradation for S. aureus compared to A. baumannii. However, SPB promoted growth of P. aeruginosa biofilm due likely to its degrading protein factors that are responsible for biofilm detachment and dispersion, thus resulting in more multi-layered biofilm formation. Commercial protease Savinase which was used as a comparison showed degradation for all three bacterial biofilms. The results obtained are unique and will expand our understanding on the effects that bacterial proteases have toward biofilms.

Isolation of Proteolytic Enzyme from Pineapple Crown

The pineapple waste from the pineapple industry has contributed to an increase in waste in Malaysia and worldwide every year. A major type of endopeptidase enzymes found in pineapple is fruit bromelain, stem bromelain, ananain, and comasain. This study aims to extract and purify protease from the crown of MD2 pineapple. Protease was extracted and purified using anion exchange chromatography, gel filtration, and desalting before being identified using liquid chromatography-mass spectrometry (LC-MS). Proteolytic activity was determined using the well diffusion method and Casein Digestion Unit. In the present study, the proteolytic assay showed that 1 kg crown of MD2 cultivar produced an activity of 126.0 ± 3.86 U/ml, a specific activity of 3937.50 U/mg. In the present study, the proteolytic assay showed that 1 kg crown of MD2 cultivar produced an activity of 126.0 ± 3.86 U/mL, a specific activity of 3937.50 U/mg and the total activity of 3.94 × 109 U. The molecular weight of the purified enzyme was in the range of 25 to 35 kDa under the optimum condition of pH 7 and 37°C. Purification of the extract yielded a band at the molecular weight of 20–25 kDa at the optimum pH of 3 and 9 at 60°C. From LC-MS analysis, the purified enzyme from the crown extract was similar to ananain under accession number A0A199VSS3 (according to Uniprot). It had five unique peptides and covered 97/356 amino acids (44.9% coverage). The ananain (EC 3.4.22.31) is classified in the subfamilies of cysteine protease C1A (clan CA, family C1), a peptidase family related to papain. In conclusion, protease was extracted and identified as an ananain-like protease from the crown.

Microbiomes of biohydrogen production from dark fermentation of industrial wastes: current trends, advanced tools and future outlook

Biohydrogen production through dark fermentation is very attractive as a solution to help mitigate the effects of climate change, via cleaner bioenergy production. Dark fermentation is a process where organic substrates are converted into bioenergy, driven by a complex community of microorganisms of different functional guilds. Understanding of the microbiomes underpinning the fermentation of organic matter and conversion to hydrogen, and the interactions among various distinct trophic groups during the process, is critical in order to assist in the process optimisations. Research in biohydrogen production via dark fermentation is currently advancing rapidly, and various microbiology and molecular biology tools have been used to investigate the microbiomes. We reviewed here the different systems used and the production capacity, together with the diversity of the microbiomes used in the dark fermentation of industrial wastes, with a special emphasis on palm oil mill effluent (POME). The current challenges associated with biohydrogen production were also included. Then, we summarised and discussed the different molecular biology tools employed to investigate the intricacy of the microbial ecology associated with biohydrogen production. Finally, we included a section on the future outlook of how microbiome-based technologies and knowledge can be used effectively in biohydrogen production systems, in order to maximise the production output.

Implications for industrial application of bioflocculant demand alternatives to conventional media: waste as a substitute

The biodegradability and safety of the bioflocculants make them a potential alternative to non-biodegradable chemical flocculants for wastewater treatment. However, low yield and production cost has been reported to be the limiting factor for large scale bioflocculant production. Although the utilization of cheap nutrient sources is generally appealing for large scale bioproduct production, exploration to meet the demand for them is still low. Although much progress has been achieved at laboratory scale, Industrial production and application of bioflocculant is yet to be viable due to cost of the production medium and low yield. Thus, the prospects of bioflocculant application as an alternative to chemical flocculants is linked to evaluation and utilization of cheap alternative and renewable nutrient sources. This review evaluates the latest literature on the utilization of waste/wastewater as an alternative substitute for conventional expensive nutrient sources. It focuses on the mechanisms and metabolic pathways involved in microbial flocculant synthesis, culture conditions and nutrient requirements for bioflocculant production, pre-treatment, and also optimization of waste substrate for bioflocculant synthesis and bioflocculant production from waste and their efficiencies. Utilization of wastes as a microbial nutrient source drastically reduces the cost of bioflocculant production and increases the appeal of bioflocculant as a cost-effective alternative to chemical flocculants.

Development of a new culture medium for bioflocculant production using chicken viscera

The economy of mass bioflocculant production and its industrial application is couple with the cost of production. The growth medium is the most significant factor that accounts for the production cost. In order to find a substitute for the expensive commercial media mostly the carbon and nitrogen sources used for bioflocculant production, we use chicken viscera as a sole source of nutrient for bioflocculant production. The culture conditions for Aspergillus flavus S44-1 growth and bioflocculant yield were optimized through one factor at a time (OFAT). The use of chicken viscera as a sole source to develop a culture medium seems to be more appropriate, simple, reduce cost of bioflocculant production and in addition offers a sustainable means of managing environmental pollution by the poultry waste. In this article, we focus on detailed description of the steps involve in developing an optimized culture medium using chicken viscera as a sole source for bioflocculant production.

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A new media for bioflocculant production was developed from chicken viscera.

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The culture conditions for bioflocculant production were determined and optimized.

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The bioflocculant yield and efficiency were parallel to mycelial weight at log phase.

Flocculation behaviour of bioflocculant produced from chicken viscera

The flocculation performance of bioflocculant produced by Aspergillus flavus S44-1 grown on chicken viscera hydrolysate was investigated. The investigations were carried out using jar testing and kaolin clay suspension as model wastewater. The bioflocculant yielded a minimum of 83.1% efficiency in flocculating 2-12 g L-1 kaolin clay suspension over a wide temperature range (4-80 °C) and functioned maximally at neutral pH. The bioflocculant significantly flocculated different suspended particles such as activated carbon (92%), soil solid (94.8%), and algae (69.4%) at varying concentrations. Bridging mediated by cation is suggested as the main mechanism of flocculation by the present bioflocculant.

Effect of surface roughness on susceptibility of Escherichia coli biofilm to benzalkonium chloride

The inherent natural tendency of bacteria to adhere and form biofilm on both biotic and abiotic surfaces and the consequential resistance to antimicrobial treatments remained a major concerned to humanity. The surface roughness of the sand blasted and cleaned stainless steel (type 304) substrates were measured using 3D measuring laser microscope before biofilm were developed on different surface roughness under continuous nutrient supply. The effect of benzalkonium chloride (BKC) as antibacterial agent on the biofilms was investigated. A concentration of 5 mg/mL BKC exert no pronounced effect on the biofilm formed on the three surfaces as compared to the 10 mg/mL and 20 mg/mL that removed approximately 50% of the cells from the respective surfaces. Conversely, the overall effect of the three concentrations tested were significantly higher (p ≤ 0.05) on the stainless steel coupon with the least average surface roughness of 0.38 ± 1.5 µm. These observations support the hypothesis that surface profile is one of the factors that influence biofilm susceptibility to antibacterial agents and reinforced the wide spread observation that microorganisms living as biofilm tends to be resistance to antimicrobial treatment especially at lower concentrations of 5 mg/mL.