Tracking Bacterial Nanocellulose in Animal Tissues by Fluorescence Microscopy

Toxicological Characteristics of Bacterial Nanocellulose in an In Vivo Experiment-Part 2: Immunological Endpoints, Influence on the Intestinal Barrier and Microbiome

Bacterial nanocellulose (BNC) is considered a promising alternative to microcrystalline cellulose, as well as an ingredient in low-calorie dietary products. However, the risks of BNC when consumed with food are not well characterized. The aim of this study is to investigate the impact of BNC on immune function, the intestinal microbiome, intestinal barrier integrity, and allergic sensitization in subacute experiments on rats. Male Wistar rats received BNC with a diet for eight weeks in a dose range of 1-100 mg/kg of body weight. The measurements of serum levels of cytokines, adipokines, iFABP2, indicators of cellular immunity, composition of the intestinal microbiome, and a histological study of the ileal mucosa were performed. In a separate four-week experiment on a model of systemic anaphylaxis to food antigen, BNC at a dose of 100 mg/kg of body weight did not increase the severity of the reaction or change the response of IgG antibodies. Based on dose-response effects on immune function, the non-observed adverse effect level for BNC was less than 100 mg/kg of body weight per day. The effects of BNC on the gut microbiome and the intestinal mucosal barrier were not dose-dependent. Data on the possible presence of prebiotic effects in BNC have been obtained.

Bacterial Cellulose In Vitro Uptake by Macrophages, Epithelial Cells, and a Triculture Model of the Gastrointestinal Tract

Bacterial cellulose (BC) has a long-standing human consumption history in different geographies without any report of adverse effects. Despite its unique textural and functional properties, the use of BC in food products in Europe is still restricted due to concerns over its nanosize. Here, we evaluated the potential uptake of celluloses (from plant and microbial sources, processed using different blenders) by macrophages (differentiated THP-1 cells) and human intestinal epithelial cells (Caco-2 and HT29-MTX cells) without (coculture) or with (triculture) Raji-B cells. A carbohydrate-binding module coupled to a green fluorescent protein was employed to observe cellulose in the cell cultures by confocal laser scanning microscopy and stimulated emission depletion microscopy. The methodology demonstrated excellent sensitivity, allowing detection of single nanocrystals within cells. All celluloses were taken up by the macrophages, without significantly compromising the cell's metabolic viability. The viability of the cocultures was also not affected. Furthermore, no internalization was observed in the triculture cell model that was exposed 24 h to BC and Avicel LM310. When (rarely) detected, cellulose particles were found on the apical side of the membrane. Overall, the obtained results suggest that BC should not be absorbed into the human gut.

Sustainable synthesis pathways: Bacterial nanocellulose from lignocellulosic biomass for circular economy initiatives

The hydrothermal pretreatment process stands out as a pivotal step in breaking down the hemicellulosic fraction of lignocellulosic biomasses, such as sugarcane bagasse and eucalyptus sawdust. This pretreatment step is crucial for preparing these materials for subsequent processes, particularly in food applications. This technique aims to disintegrate plant wall components like cellulose, hemicellulose, and lignin, and facilitating access in later phases such as enzymatic hydrolysis, and ultimately making fermentable sugars available. In this study, sugarcane bagasse and eucalyptus sawdust biomass underwent hydrothermal pretreatment at specific conditions, yielding two key components: dry biomass and hemicellulose liquor. The primary focus was to assess the impact of hydrothermal pretreatment followed by enzymatic hydrolysis, using the Celic Ctec III enzyme cocktail, to obtain fermentable sugars. These sugars were then transformed into membranes via strain Gluconacetobacter xylinus bacterial biosynthesis. Notably, the addition of a nitrogen source significantly boosted production to 14.76 g/ in hydrolyzed sugarcane bagasse, underscoring its vital role in bacterial metabolism. Conversely, in hydrolyzed eucalyptus, nitrogen source inclusion unexpectedly decreased yield, highlighting the intricate interactions in fermentation media and the pivotal influence of nitrogen supplementation. Characterization of membranes obtained in synthetic and hydrolyzed media through techniques such as FEG-SEM, FTIR, and TGA, followed by mass balance assessment, gauged their viability on an industrial scale. This comprehensive study aimed not only to understand the effects of pretreatment and enzymatic hydrolysis but to also evaluate the applicability and sustainability of the process on a large scale, providing crucial insights into its feasibility and efficiency in practical food-related scenarios, utilizing nanocellulose bacterial (BNC) as a key component.

Opportunities for bacterial nanocellulose in biomedical applications: Review on biosynthesis, modification and challenges

Bacterial nanocellulose (BNC) is a natural polysaccharide produced as extracellular material by bacterial strains and has favorable intrinsic properties for primary use in biomedical applications. In this review, an update on state-of-the art and challenges in BNC production, surface modification and biomedical application is given. Recent insights in biosynthesis allowed for better understanding of governing parameters improving production efficiency. In particular, introduction of different carbon/nitrogen sources from alternative feedstock and industrial upscaling of various production methods is challenging. It is important to have control on the morphology, porosity and forms of BNC depending on biosynthesis conditions, depending on selection of bacterial strains, reactor design, additives and culture conditions. The BNC is intrinsically characterized by high water absorption capacity, good thermal and mechanical stability, biocompatibility and biodegradability to certain extent. However, additional chemical and/or physical surface modifications are required to improve cell compatibility, protein interaction and antimicrobial properties. The novel trends in synthesis include the in-situ culturing of hybrid BNC nanocomposites in combination with organic material, inorganic material or extracellular components. In parallel with toxicity studies, the applications of BNC in wound care, tissue engineering, medical implants, drug delivery systems or carriers for bioactive compounds, and platforms for biosensors are highlighted.

Synthesis, Applications and Biological Impact of Nanocellulose

Interest in cellulose-based nanomaterials has continued to increase dramatically in the past few years, especially with advances in the production routes of nanocellulose-such as cellulose nanocrystals (CNC), cellulose nanofibrils (CNF) and bacterial nanocellulose (BNC)-that tailor their performances [...].