A novel nanomaterial, bacterial cellulose (BC), has become noteworthy recently due to its better physicochemical properties and biodegradability, which are desirable for various applications. Since cost is a significant limitation in the production of cellulose, current efforts are focused on the use of industrial waste as a cost-effective substrate for the synthesis of BC or microbial cellulose. The utilization of industrial wastes and byproduct streams as fermentation media could improve the cost-competitiveness of BC production. This paper examines the feasibility of using typical wastes generated by industry sectors as sources of nutrients (carbon and nitrogen) for the commercial-scale production of BC. Numerous preliminary findings in the literature data have revealed the potential to yield a high concentration of BC from various industrial wastes. These findings indicated the need to optimize culture conditions, aiming for improved large-scale production of BC from waste streams.

Simultaneous power generation and wastewater treatment in the single chamber air cathode microbial fuel cell have been enhanced by introducing wild-type Klebsiella variicola as an efficient inoculum for the anode operated with palm oil mill effluent.

The interspecies interactions in microbial communities are very complex, rendering identification of synergistic or antagonistic relationships very difficult; however, understanding the mutualistic relationship between the microbes is exigent to gain deeper insight into their performance in wastewater fed microbial fuel cells (MFCs). In the present study, we aimed to explore the ecological networks between the microorganisms in a defined coculture system comprising with Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella variicola (K. variicola). The coculture showed around 3 times higher current density in MFCs compared with either of these two bacteria alone. Metabolite analysis demonstrated that the fermentative metabolite (1,3-propanediol) produced by K. variicola stimulated the P. aeruginosa to produce a higher amount of pyocyanin through synergistic interactions, leading to the enhancement in the performance of coculture MFCs fed with palm oil mill effluent (POME). This study proves that the metabolite based “interspecies ecological communicatio” can enhance the electrochemical activity in MFCs.

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Anodic biofilm plays a crucial role in bioelectrochemical system to make it sustainable for long-term performance. However, the accumulation of dead cells over time within the anode biofilm can be particularly detrimental for current generation. In this study, the effect of ultrasound on anode biofilm thickness was investigated in microbial fuel cells (MFCs). Ultrasonic treatment was employed for different durations to evaluate its ability to control the thickness of the biofilm to maintain stable power generation. Cell viability count and field emission scanning electron microscopy (FESEM) analysis of the biofilms over time showed that the number of dead cells increased with the increase of biofilm thickness, and eventually exceeded the number of live cells by many-fold. Electrochemical impedance spectroscopy (EIS) analysis indicated that the high polarization resistance appeared due to the dead layer formation, and thus the catalytic efficiency was reduced in MFCs. The stable power generation was achieved by employing ultrasonic treatment for 30 min every 6 days with some initial exception. The low frequency ultrasound treatment successfully dislodged the ineffective biofilm from the surface of the anode. Moreover, the ultrasound could increase the mass transfer rate of the nutrients and cellular waste through the biofilm leading to the increase in cell growth. Therefore, ultrasonic treatment is verified as an efficient method to control the thickness of the biofilm as well as enhance the cell viability in biofilm thereby maintaining the stable power generation in the MFC.

Mutual interactions between microorganisms play a vital role in the formation of electroactive biofilms, which is a key element in the longevity and success of bioelectrochemical systems. The present study was intended to examine both the electrogenic properties of B. cereus and its ability to inhibit methanogenesis in microbial fuel cells (MFCs). The potential influence of the incorporation of B. cereus into anaerobic sludge (AS) on the electrochemical activity was assessed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. The CV of MFCs with B. cereus showed a strong redox peak, suggesting that B. cereus has electrogenetic properties. Moreover, the incorporation of B. cereus into AS provided an enhancement in the power generation (4.83 W/m 3 ) and the CE (22%) of the MFC compared to the corresponding values for an MFC inoculated solely with AS (1.82 W/m 3 , 12%). The increase in power generation could be due to the antimethanogenic property of B. cereus, which was evident from the 54% reduction in methane production. The results of this study suggest that the incorporation of microorganisms with electrogenic and antimethanogenic properties into AS promotes the formation of electroactive biofilms and maximizes the power generation of MFCs by suppressing the methanogenesis.

Although exogenous mediators can distinctly enhance the performance of yeast driven microbial fuel cell (MFC), the possibility of mediator's toxicity, environmental risk, and cost are the main challenges facing toward its application in MFCs. Therefore, the use of naturally produced electron shuttles for unmediated yeast would be of great interest since it can solve most of the above-mentioned problems. The present study is to investigate the possibility of the use of electron shuttle producing bacteria Klebsiella pneumonia (K. pneumonia) to boost up the performance of yeast Lipomyces starkeyi (L. starkeyi) driven MFC. The MFCs inoculated with L. starkeyi and K. pneumoniae coculture achieved a maximum power density of 12.87 W/m 3 which is about 3 and 6 times higher than that of MFC solely inoculated with pure yeast and bacteria, respectively, demonstrating that the yeast cells have successfully utilized the reduced electron shuttles excreted by the bacteria. The occurrence of the mutualistic interactions was further supported by the CV and EIS results. The findings of this work suggest that the use of mutualistic interaction of yeast and bacteria could be a new way to increase the performance of the MFCs.

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