Emerging development of nanocellulose as an antimicrobial material: An overview

The prolonged survival of microbes on surfaces in high-traffic/high-contact environments drives the need for a more consistent and passive form of surface sterilization to minimize the risk of infection. Due to increasing tolerance to antibiotics among microorganisms, research focusing on the discovery of naturally-occurring biocides with low-risk cytotoxicity properties has become more pressing. The latest research has centred on nanocellulosic antimicrobial materials due to their low-cost and unique features, which are potentially useful as wound dressings, drug carriers, packaging materials, filtration/adsorbents, textiles, and paint. This review discusses the latest literature on the fabrication of nanocellulose-based antimicrobial materials against viruses, bacteria, fungi, algae, and protozoa by employing variable functional groups, including aldehyde groups, quaternary ammonium, metal, metal oxide nanoparticles as well as chitosan. The problems associated with industrial manufacturing and the prospects for the advancement of nanocellulose-based antimicrobial materials are also addressed

Bioelectricity generation from sago hampas by Clostridium beijerinckii SR1 using microbial fuel cells

Sago hampas is a starch-based biomass resulted from the sago starch extraction process that has potential to be a substrate for bioenergy production. Microbial fuel cells (MFCs) is a promising technology that employ the microorganisms to utilize the substrate, which then generate the electrical power. Therefore, through the concept of biomass fuel cells, this study was aimed to utilize sago hampas as substrate in microbial fuel cells to generate the bioelectricity by Clostridium beijerinckii SR1, via sugar and volatile fatty acids (VFAs) platform and direct biomass utilization system. A single culture, C. beijerinckii SR1 has been employed to produce VFAs from 40 g/L of sago hampas (containing 20 g/L of starch content), resulted 6.71 g/L of total VFAs with the VFAs yield of 0.30 g/g. The enhancement of VFAs from sago hampas was conducted using one-factor-at-a-time (OFAT) with the variables of carbon sources concentration, nitrogen (yeast extract) concentration and addition of inorganic nitrogen sources. The production of VFA has successfully enhanced by 14.6%, with the OFAT condition obtained was 3% (w/v) of sago hampas, 3 g/L of yeast extract and the additional 2 g/L of NH4NO3, resulted the production of VFAs (7.69 g/L) with 0.45 g/g of VFAs yield. Furthermore, the effect of sugar and VFAs platform from sago hampas on the bioelectricity generation using microbial fuel cells were studied. The results showed the VFAs platform of sago hampas has better bioelectricity generation, in term of maximum power density (max PD) as compared to sugar platform. The highest max PD obtained was 72.62 mW/m2 from 2 g/L of VFAs hydrolysate. At the final stage, direct biomass fuel cells was performed using sago hampas directly as a substrate in MFCs. Result shown that 73.78 mW/m2 of maximum power density was obtained from direct biomass fuel cells by C. beijerinckii SR1. This result shows a comparable maximum power density as compared to VFAs platform of sago hampas. Overall, the generation of bioelectricity from sago hampas has been successfully studied using microbial fuel cells system by C. beijerinckii SR1

Biohydrogen production from sago hampas by Clostridium butyricum A1

The hydrogen has been applied in fuel cell vehicle and expected to shift toward the technologies that produce no net greenhouse gas effects. Biohydrogen production from biomass is now attracting many researchers in developing a renewable, clean and environmental friendly biofuel. The availability of abundant biomass from various sources could possibly be an advantage for the production of biohydrogen as a competitive energy carrier in the future. There are vast choices of possible types of biomass that can be subjected as the carbon source for the production of biohydrogen including starch based and lignocellulosic biomass. Sago industry is one of the possible source of biomass since the industry is producing large quantities of starch and lignocellulosic biomass. Statistically, a single sago starch processing mill has produced 7 ton/day of sago hampas. Thus, this study aimed to produce biohydrogen from sago biomass by locally isolated biohydrogen producer and to optimize the production of biohydrogen using statistical approach. The locally isolated biohydrogen producer Clostridium butyricum A1 was successfully isolated from landfill soil. This strain produced a biohydrogen yield of 1.90 mol H2/mol glucose with productivity of 170 mL/L/h using pure glucose as substrate. The highest cumulative biohydrogen collected after 24 h of fermentation time was 2468 mL/Lmedium. Biohydrogen fermentation using sago hampas hydrolysate generate higher biohydrogen yield (2.65 mol H2/mol glucose) compared to sago pith residue (SPR) hydrolysate at 2.23 mol H2/mol glucose. A higher biohydrogen productivity of 1757 mL/L/h was obtained when using sago hampas hydrolysate much higher when compared to pure glucose at 170 mL/L/h. In this study, the new isolate C. butyricum A1 together with the use of sago biomass as the substrate is a promising technology for future biohydrogen production. Optimization of biohydrogen production from sago hampas hydrolysate by C. butyricum A1 was conducted using four variables including temperature, sugar concentration, initial pH and inoculum size. This study has applied central composite design (CCD) and artificial neural network (ANN) as the optimization step. As a result, three out of four variables have given significant effects on the production of biohydrogen from sago hampas hydrolysate; which are temperature, sugar concentration and pH. Using ANN, pH was found to be the most significant variable with the relative importance of 73.6%. The optimum conditions given by ANN with respect to optimized biohydrogen yield of 2.92 mol of H2/mol of glucose are 39°C, pH 8, initial glucose concentration at 13 g/L and 13% (v/v) inoculum size. As conclusions,biohydrogen production from sago hampas by C. butyricum A1 has successfully conducted and optimized

Enhanced volatile fatty acid production from sago hampas by Clostridium beijerinckii SR1 for bioelectricity generation using microbial fuel cells

Sago hampas is a starch-based biomass from sago processing industries consisted of 58% remaining starch. This study has demonstrated the bioconversion of sago hampas to volatile fatty acids (VFAs) by Clostridium beijerinckii SR1 via anaerobic digestion. Higher total VFAs were obtained from sago hampas (5.04 g/L and 0.287 g/g) as compared to commercial starch (5.94 g/L and 0.318 g/g). The physical factors have been investigated for the enhancement of VFAs production using onefactor-at-a-time (OFAT). The optimum condition; 3% substrate concentration, 3 g/L of yeast extract concentration and 2 g/L of ammonium nitrate enhanced the production of VFAs by 52.6%, resulted the total VFAs produced is 7.69 g/L with the VFAs yield of 0.451 g/g. VFAs hydrolysate produced successfully generated 273.4 mV of open voltage circuit and 61.5 mW/m2 of power density in microbial fuel cells. It was suggested that sago hampas provide as an alternative carbon feedstock for bioelectricity generation

Effect of Buffering System on Acetone-Butanol-Ethanol Fermentation by Clostridium acetobutylicum ATCC 824 using Pretreated Oil Palm Empty Fruit Bunch

Change of pH has been identified as the most significant parameter in modulating the transition between the conversions of acids into solvents in acetone-butanol-ethanol (ABE) fermentation by Clostridia. Thus, ABE fermentation at various phosphate buffer concentrations and initial pH values was conducted using pure glucose and sugars derived from pretreated oil palm empty fruit bunch (OPEFB). A higher solvent concentration (2.93 g/L) was obtained in the fermentation using 20 g/L of glucose with buffer compared with one without buffer that produced 1.34 g/L of solvents. Approximately 8.77 and 9.15 g/L of solvents were produced from fermentation using 40 g/L of glucose with and without buffer, respectively. In the latter conditions, at an initial pH of 5.5, 8.77 g/L of solvents was obtained, which was the highest concentration compared to other initial pH values. Increasing the buffer concentration to 0.2 M at an initial pH of 6.0 resulted in acid accumulation of 16.83 g/L but reduced the solvent production to 1.36 g/L. In addition, ABE fermentation using 20 g/L of sugars from pretreated OPEFB produced 2.25 g/L of solvents with a yield of 0.13 g/g, which was comparable with fermentation using 20 g/L of glucose conducted in a buffering system

Sago biomass as a sustainable source for biohydrogen production by Clostridium butyricum A1

Biohydrogen production from biomass is attracting many researchers in developing a renewable, clean and environmental friendly biofuel. The biohydrogen producer, Clostridium butyricum A1, was successfully isolated from landfill soil. This strain produced a biohydrogen yield of 1.90 mol H2/mol glucose with productivity of 170 mL/L/h using pure glucose as substrate. The highest cumulative biohydrogen collected after 24 h of fermentation was 2468 mL/L-medium. Biohydrogen fermentation using sago hampas hydrolysate produced higher biohydrogen yield (2.65 mol H2/mol glucose) than sago pith residue (SPR) hydrolysate that produced 2.23 mol H2/mol glucose. A higher biohydrogen productivity of 1757 mL/L/h was obtained when using sago hampas hydrolysate compared to when using pure glucose that has the productivity of 170 mL/L/h. A comparable biohydrogen production was also obtained by C. butyricum A1 when compared to C. butyricum EB6 that produced a biohydrogen yield of 2.50 mol H2/mol glucose using sago hampas hydrolysate as substrate. This study shows that the new isolate C. butyricum A1 together with the use of sago biomass as substrate is a promising technology for future biohydrogen production

Sago biomass as a sustainable source for biohydrogen production by clostridium butyricum A1

Biohydrogen production from biomass is attracting many researchers in developing a renewable, clean and environmental friendly biofuel. The biohydrogen producer, Clostridium butyricum A1, was successfully isolated from landfill soil. This strain produced a biohydrogen yield of 1.90 mol H2/mol glucose with productivity of 170 mL/L/h using pure glucose as substrate. The highest cumulative biohydrogen collected after 24 h of fermentation was 2468 mL/L-medium. Biohydrogen fermentation using sago hampas hydrolysate produced higher biohydrogen yield (2.65 mol H2/mol glucose) than sago pith residue (SPR) hydrolysate that produced 2.23 mol H2/mol glucose. A higher biohydrogen productivity of 1757 mL/L/h was obtained when using sago hampas hydrolysate compared to when using pure glucose that has the productivity of 170 mL/L/h. A comparable biohydrogen production was also obtained by C. butyricum A1 when compared to C. butyricum EB6 that produced a biohydrogen yield of 2.50 mol H2/mol glucose using sago hampas hydrolysate as substrate. This study shows that the new isolate C. butyricum A1 together with the use of sago biomass as substrate is a promising technology for future biohydrogen production

Direct bioelectricity generation from sago hampas by Clostridium beijerinckii SR1 using microbial fuel cell

Microbial fuel cells offer a technology for simultaneous biomass degradation and biological electricity generation. Microbial fuel cells have the ability to utilize a wide range of biomass including carbohydrates, such as starch. Sago hampas is a starchy biomass that has 58% starch content. With this significant amount of starch content in the sago hampas, it has a high potential to be utilized as a carbon source for the bioelectricity generation using microbial fuel cells by Clostridium beijerinckii SR1. The maximum power density obtained from 20 g/L of sago hampas was 73.8 mW/cm2 with stable cell voltage output of 211.7 mV. The total substrate consumed was 95.1% with the respect of 10.7% coulombic efficiency. The results obtained were almost comparable to the sago hampas hydrolysate with the maximum power density 56.5 mW/cm2. These results demonstrate the feasibility of solid biomass to be utilized for the power generation in fuel cells as well as high substrate degradation efficiency. Thus, this approach provides a promising way to exploit sago hampas for bioenergy generation

Functional Properties of Pineapple Plant Stem for Enhanced Glucose Recovery in Amino Acids Production

Pineapples generate large amounts of agricultural wastes during their production. To reduce environmental impacts due to poor handling of these wastes, the underutilised pineapple plant stem (PPS), which has a high starch content, can be explored for its sugar recovery. To achieve this, gelatinisation is a key process in increasing enzymes’ susceptibility. Therefore, this study aimed to enhance glucose recovery from PPS by studying the effects of gelatinisation temperature and time on its functional properties. Afterwards, the fermentable sugar obtained was used for amino acids production by Bacillus subtilis ATCC 6051. PPS has a high gelatinisation temperature (To = 111 °C; Tp = 116 °C; Tc = 161 °C) and enthalpy (ΔH = 263.58 J/g). Both temperature and time showed significant effects on its functional properties, affecting enzymatic hydrolysis. Gelatinisation temperature of 100 °C at 15 min resulted in maximum glucose recovery of 56.81 g/L (0.81 g/g hydrolysis yield) with a 3.53-fold increment over the control. Subsequently, utilisation of PPS hydrolysate in the fermentation by B. subtilis ATCC 6051 resulted in 23.53 mg/mL amino acids being produced with productivity of 0.49 g/L/h. This opens up new opportunities for the applications of PPS as well as B. subtilis ATCC 6051 in the amino acids industry

Pineapple peel as alternative substrate for bacterial nanocellulose production

Due to its flexible properties, bacterial nanocellulose (BNC) has been attracting tremendous attention. In this study, BNC was produced by Acetobacter xylinum ATCC2376 and a local isolate, namely, Bacillus cereus MMS1. The production of BNC was done by utilising pineapple peel extract (PPE) (wastes discarded after cutting the fruit) as the alternative carbon source substituting the commercial D-glucose (control) in Hestrin–Schramm (HS) medium under agitated conditions. This research is aimed to investigate the synthesis of BNC by an isolated bacterial strain from termite’s gut using an agro-industrial waste which is the pineapple peel extract. Six bacterial strains, namely, F8, F5, M1, M6, H7 and H11, were screened and identified for potential BNC producer. The selected bacterial strain was identified as Bacillus cereus MMS1 using 16S rRNA nucleotide sequences. Then, the production of BNC was done by B. cereus MMS1 using pineapple peel extract, while A. xylinum ATCC2376 acted as a control. The BNC production in this study was attained at 2% (w/v) glucose concentration, 12 days of incubation period and 150 rpm agitation speed which was 5.83 g/L by A. xylinum ATCC2376 in HS medium using commercial glucose as carbon source. Meanwhile, 4.42 g/L and 2 g/L of BNC were produced by B. cereus MMS1 after 12 days of incubation with an initial concentration of 2% (w/v) using commercial glucose and pineapple peel extract, respectively