Bacterial cellulose producers

The best studied BC producers are the acetic acid bacteria (AAB). They are gram-negative and obligate aerobic bacteria found in a variety of natural sources that are rich in sugar and alcohols (e.g. fruits and fermented foods) (Yang et al., Reference Yang, Chen, Wang, Zhou, Liebl, Barja and Chen2022). AAB phenotypes relate to the acetic acid production, nitrogen fixation (Fuentes-Ramírez et al., Reference Fuentes-Ramírez, Bustillos-Cristales, Tapia-Hernández, Jiménez-Salgado, Wang, Martínez-Romero and Caballero-Mellado2001), pigment production (Malimas et al., Reference Malimas, Yukphan, Takahashi, Muramatsu, Kaneyasu, Potacharoen, Tanasupawat, Nakagawa, Tanticharoen and Yamada2009) and exopolysaccharides generation (Tonouchi, Reference Tonouchi, Matsushita, Toyama, Tonouchi and Okamoto-Kainuma2016; La China et al., Reference La China, Zanichelli, De Vero and Gullo2018; Barja, Reference Barja2021). These microorganisms are also known for producing several aldehydes, ketones and other organic acids through oxidative fermentation (Mamlouk & Gullo, Reference Mamlouk and Gullo2013; Lynch et al., Reference Lynch, Zannini, Wilkinson, Daenen and Arendt2019). Besides producing these compounds AAB can also accumulate a large amount of them extracellularly as happens with BC (Mamlouk & Gullo, Reference Mamlouk and Gullo2013; Lynch et al., Reference Lynch, Zannini, Wilkinson, Daenen and Arendt2019). The most prolific AAB in terms of BC production is Komagataeibacter xylinus (Römling & Galperin, Reference Römling and Galperin2015; Gullo et al., Reference Gullo, Sola, Zanichelli, Montorsi, Messori and Giudici2017). During the past years, several reviews have been published to elucidate the details of AAB taxonomy (Trček & Barja, Reference Trček and Barja2015; Yamada, Reference Yamada, Matsushita, Toyama, Tonouchi and Okamoto-Kainuma2016), biotechnological applications (Saichana et al., Reference Saichana, Matsushita, Adachi, Frébort and Frebortova2015), resistance mechanisms (Nakano & Ebisuya, Reference Nakano, Ebisuya, Matsushita, Toyama, Tonouchi and Okamoto-Kainuma2016; Qiu et al., Reference Qiu, Zhang and Hong2021) and BC production (Gullo et al., Reference Gullo, La China, Falcone and Giudici2018; De Amorim et al., Reference De Amorim, De Souza, Duarte, Da Silva Duarte, De Assis Sales Ribeiro, Silva, De Farias, Stingl, Costa, Vinhas and Sarubbo2020; Barja, Reference Barja2021); however, there are yet research questions in need to be answered. These questions relates simultaneously to the diversity of BC producers and their associated BC biosynthesis pathways.

Apart from K. xylinus, several AAB species are also known to produce BC. Among them are members of the genera Komagataeibacter, Acetobacter, Gluconacetobacter, Rhizobia, Rhodobacter, Agrobacterium and Sarcina (Delmer, Reference Delmer1999; Brown, Reference Brown2004; Morgan et al., Reference Morgan, Strumillo and Zimmer2013, Matsutani et al., Reference Matsutani, Ito, Azuma, Ogino, Shirai, Yakushi and Matsushita2015). Other non-AAB species can also produce BC such as Achromobacter, Alcaligenes, Aerobacter, Azotobacter, Pseudomonas, Dickeya and Lactobacillus (Deinema & Zevenhuizen, Reference Deinema and Zevenhuizen1971; Brown, Reference Brown2004; Jahn et al., Reference Jahn, Selimi, Barak and Charkowski2011; Morgan et al., Reference Morgan, Strumillo and Zimmer2013; Khan et al., Reference Khan, Kadam and Dutt2020). As an example, Khan et al. (Reference Khan, Kadam and Dutt2020), characterised a Lactobacillus hilgardii strain capable of producing BC in high quantities. Using a fructose-rich medium, they observed that L. hilgardii was able to produce immensely pure and crystalline BC with a yield of 7.23 g/ L after 16 days of incubation. Hence, the plethora of organisms able to produce BC represent novel routes of research to detect, engineer, characterise and standardise the best possible BC producer.

One of the easiest ways of producing BC is through kombucha fermentation. Kombucha is a slightly alcoholic and carbonated beverage resulting from the fermentation of a tea-based aqueous solution and sugar by a symbiotic culture of bacteria and yeast (SCOBY) (Villareal-Soto et al., Reference Villarreal-Soto, Beaufort, Bouajila, Souchard and Taillandier2018). At the aqueous-air interface, there is the deposition of BC that forms a layer at the surface of the liquid. This pellicle can be collected by hand for further treatment without any intricate technique. Microbiologically, kombucha is constituted by the AAB such as Gluconobacter sp., Acetobacter sp., Komagataeibacter sp. (de Roos & de Vuyst, Reference De Roos and De Vuyst2018), lactic acid bacteria such as Lactococcus sp. and Lactobacillus sp. Yeasts such as Zygosaccharomyces bailii, Saccharomyces cerevisae, Schizosaccharomyces pombe, Saccharomycodes ludwigii, Kloeckera apiculata, Torulaspora delbrueckii and Brettanomyces bruxellensis have also been detected (Coton et al., Reference Coton, Pawtowski, Taminiau, Burgaud, Deniel, Coulloumme-Labarthe, Fall, Daube and Coton2017; Laavanya et al., Reference Laavanya, Shirkole and Balasubramanian2021).

A recent study by Keating et al. (Reference Keating, Van Zyl, Collins, Nakagawa, Weintraub, Coburn and Young2023) has argued for a formation of a new taxonomy – Novacetimonas hansenii – to incorporate a BC overproducer strain (N. hansenii NQ5) due to insights gained from whole genome analysis. In support of this taxonomical rearrangement, Ryngajłło et al. (Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019) investigated 19 Komagataeibacter genomes and concluded that there was sufficient evidence to distinguish between the K. xylinus and K. hansenii clades. They found variance in the genomic traits related to the carbohydrate uptake and regulation of its metabolism, exopolysaccharide synthesis, plasmid DNA content and the c-di-GMP signalling network that explain the phenotypic diversity found in these clades. This new knowledge represents research routes yet to be explored that directly and indirectly influence BC generation.

Bacterial cellulose biochemistry and synthesis limiting factors

BC possesses better physico-mechanical properties than the plant-derived cellulose due to its nanofibrous 3D structure (Ul-Islam et al., Reference Ul-Islam, Khan and Park2012). Additionally, BC has a high purity and crystallinity, mechanical strength, jellified appearance, porous geometry, biocompatibility and easy mouldability representing a promising material for designers (Khan et al., Reference Khan, Ul-Islam, Ullah, Zhu, Narayanan, Han and Park2022). BC is synthesised through four main sequential enzymatic steps:

1. i) Phosphorylation of glucose by the glucokinase;

2. ii) Glucose-6-phosphate isomerises into glucose-1-phosphate by the effect of the phosphoglucomutase,

3. iii) UDP-glucose is synthesised by the UDP-glucose pyrophosphorylase and

4. iv) Cellulose synthase reaction (Yoshinaga et al., Reference Yoshinaga, Tonouchi and Watanabe1997; Singhania et al., Reference Singhania, Patel, Tsai, Chen and Di Dong2021).

In the last step, UDP-glucose polymerases into cellulose by the activity of a membrane protein complex called cellulose synthase, which is an unstable high molecular mass protein that is also responsible for cellulose secretion to the extracellular matrix (El-Saied et al., Reference El-Saied, Basta and Gobran2004). The cellulose synthase consists of four core proteins that are encoded by the cellulose synthase operon containing the genes bcsABCD (Yoshinaga et al., Reference Yoshinaga, Tonouchi and Watanabe1997). However, the operon is not equally observable among the Komagataeibacter species (Saxena and Brown, Reference Saxena and Brown1995; Matsutani et al., Reference Matsutani, Ito, Azuma, Ogino, Shirai, Yakushi and Matsushita2015).

In general, cellulose producers are a relatively well-studied group of microbes but the high cost and low yield of BC production make it necessary to increase the depth of research and characterisation. Specifically, it is necessary to clarify the potential genotype-phenotype dualism related to the BC synthesis, secretion machineries and other relevant cellular processes (Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019). One example is the high phenotypic variability of Komagataeibacter (Gullo et al., Reference Gullo, La China, Falcone and Giudici2018). Since different strains can be recovered throughout the fermentation and BC production experiments (Valera et al., Reference Valera, Torija, Mas and Mateo2015; La China et al., Reference La China, Zanichelli, De Vero and Gullo2018) it is possible that a microbial consortium is needed for achieving the best results. The hypothesis is that different strains prefer different growth conditions within the same production cycle, potentiating a “cascade” effect that results in high BC yields. Therefore, BC production is strain-dependent, differing in the yields, structure and strain stability (Fang & Catchmark, Reference Fang and Catchmark2015; Chen et al., Reference Chen, Lopez-Sanchez, Wang, Mikkelsen and Gidley2018; Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019). Moreover, the fermentation substrate, the culture media and the genetic organisation of the cellulose synthase and its related genes can also account for the detected phenotypic variability (La China et al., Reference La China, Bezzecchi, Moya, Petroni, Di Gregorio and Gullo2020; Singhania et al., Reference Singhania, Patel, Tseng, Kumar, Chen, Haldar, Saini and Dong2022).

Depending if BC is produced by a SCOBY or through pure culture of strains, the substrate requirements might differ as well as other factors related to the equipment and post-production treatments (Fernandes et al., Reference Fernandes, Pedro, Ribeiro, Bortolini, Ozaki, Maciel and Haminiuk2020; Laavanya et al., Reference Laavanya, Shirkole and Balasubramanian2021; Rathinamoorthy & Kiruba, Reference Rathinamoorthy and Kiruba2022; Singhania et al., Reference Singhania, Patel, Tseng, Kumar, Chen, Haldar, Saini and Dong2022). The leading factors contributing to the BC production are the type and concentration of the nitrogen (e.g. peptone) and carbon source (e.g. glucose, sucrose), the dissolved oxygen in suspension (∼10–15%), the pH (∼4–6) and temperature (∼25–35 °C). Various types of wastes and by-products (both having complex chemical compositions) have been tried to grow BC, but the best results observed are from the experiments where additional nutrient sources are supplemented (Fernandes et al., Reference Fernandes, Pedro, Ribeiro, Bortolini, Ozaki, Maciel and Haminiuk2020; Nascimento et al., Reference Nascimento, Torres, Freitas, Reis and Crespo2021; da Silva et al., Reference Da Silva, De Medeiros, De Amorim, Do Nascimento, Converti, Costa and Sarubbo2021). Other relevant factors are the proportion (∼1:15–1:10) and age (∼3–30 days) of the inoculation and the co-substrate concentration (e.g. ethanol, vitamins) (Fernandes et al., Reference Fernandes, Pedro, Ribeiro, Bortolini, Ozaki, Maciel and Haminiuk2020; Singhania et al., Reference Singhania, Patel, Tseng, Kumar, Chen, Haldar, Saini and Dong2022). Alterations in the biochemical pathways for microbial growth and cellulose synthesis differ between strains (Masaoka et al., Reference Masaoka, Ohe and Sakota1993; Toyosaki et al., Reference Toyosaki, Naritomi, Seto, Matsuoka, Tsuchida and Yoshinaga1995; Czaja et al., Reference Czaja, Young, Kawecki and Brown2007; Ochaikul et al., Reference Ochaikul, Suwanposri, Yukphan and Yamada2013; Zeng et al., Reference Zeng, Laromaine and Roig2014; Fang & Catchmark, Reference Fang and Catchmark2015). Other soluble exopolysaccharides like acetan and its derivatives and levan that indirectly affect BC production also vary among BC-producing strains (Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019). In summary, the genetic instability of the cellulose synthase, its differential presence in AAB and the paraphernalia of other factors directly and indirectly affecting BC synthesis make its production an extremely hard experimental setup. This constitutes a major challenge for biodesigners, which would benefit from a standardisation of BC-producing experimental protocols.

Bacterial cellulose, genomics and proteomics

About the genomic features of the Komagataeibacter genus, Matsutani et al. (Reference Matsutani, Ito, Azuma, Ogino, Shirai, Yakushi and Matsushita2015) analysed the whole genome of Komagataeibacter medellinensis NBRC 3288 and found the particular genetic conditions that make this strain lose and regain the ability to synthesise BC. They also found other mutations associated with such phenotypic variance. Together, this genetic instability and easiness to lose and regain abilities related to cellulose production constitute a risk of using this strain in a standard routine. Such risk can be extrapolated to other strains belonging to the Komagataeibacter genus since these bacteria are known to have transient phenotypes in their essential metabolism (Beppu, Reference Beppu1994; Coucheron, Reference Coucheron1991; Takemura et al., Reference Takemura, Horinouchi and Beppu1991; Sokollek et al., Reference Sokollek, Hertel and Hammes1998; Azuma et al., Reference Azuma, Hosoyama, Matsutani, Furuya, Horikawa, Harada, Hirakawa, Kuhara, Matsushita, Fujita and Shirai2009; Castro et al., Reference Castro, Cleenwerck, Trček, Zuluaga, De Vos, Caro, Aguirre, Putaux and Gañán2013; La China et al., Reference La China, Bezzecchi, Moya, Petroni, Di Gregorio and Gullo2020). For instance, Florea et al. (Reference Florea, Hagemann, Santosa, Abbott, Micklem, Spencer-Milnes, De Arroyo Garcia, Paschou, Lazenbatt, Kong, Chughtai, Jensen, Freemont, Kitney, Reeve and Ellis2016a) found and described two additional cellulose synthase operons in Gluconacetobacter hansenii and several previously unknown genes related to BC production. Recently, Bimmer et al. (Reference Bimmer, Reimer, Klingl, Ludwig, Zollfrank, Liebl and Ehrenreich2023) performed a proteomic analysis on the same strain (Komagataeibacter hansenii ATCC 53582) and their characterisation of the regulatory diguanylate cyclases (dgcA and dgcB deleterious mutants) suggested a new regulatory mechanism of cellulose synthesis in K. hansenii.

Recent studies have shown the extensive involvement of the operon bcsABCD in the biosynthesis, extracellular transport and assembly of cellulose (Manan et al., Reference Manan, Ullah, Ul-Islam, Shi, Gauthier and Yang2022). The cellulose synthase enzyme is encoded by two types of operons, and both types consist of four genes:

1. i) Type I: bcsA-D (Matsutani et al., Reference Matsutani, Ito, Azuma, Ogino, Shirai, Yakushi and Matsushita2015) and

2. ii) Type II: bcsABII, bcsX, bcsY and bcsCII (Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019).

These two types of operons are subjected to mutations. Specifically, the bcsC subunits (related to the cellulose export through the membrane) are prone to disruption, suggesting that cellulose export is subject to evolutionary forces (Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019). However, the cellulose synthase is a complex enzyme and other descriptions have been referred including a third type of operon and the presence of more related genes (Römling & Galperin, Reference Römling and Galperin2015; La China et al., Reference La China, Bezzecchi, Moya, Petroni, Di Gregorio and Gullo2020; Manan et al., Reference Manan, Ullah, Ul-Islam, Shi, Gauthier and Yang2022). Despite the well-conserved function of the BcsA and BcsB (responsible for cellulose synthesis activity and β-glucan chain formation, respectively (Ross et al., Reference Ross, Mayer and Benziman1991; Yoshinaga et al., Reference Yoshinaga, Tonouchi and Watanabe1997; Park et al., Reference Park, Jung and Khan2009; Römling & Galperin, Reference Römling and Galperin2015; Morgan et al., Reference Morgan, McNamara, Fischer, Rich, Chen, Withers and Zimmer2016)), the function of BcsC and BcsD is still under debate (Saxena et al., Reference Saxena, Kudlicka, Okuda and Brown1994; Hu et al., Reference Hu, Gao, Tajima, Sunagawa, Zhou, Kawano, Fujiwara, Yoda, Shimura, Satoh, Munekata, Tanaka and Yao2010; Iyer et al., Reference Iyer, Catchmark, Brown and Tien2011). Regarding the genomic instability of the AAB, there are also the insertion sequences that cause disruptions in essential biochemical mechanisms and also hamper cellulose synthesis (Asai, Reference Asai1968; Valla et al., Reference Valla, Coucheron and Johs1987; Coucheron, Reference Coucheron1991; Takemura et al., Reference Takemura, Horinouchi and Beppu1991; Beppu, Reference Beppu1994; Coucheron, Reference Coucheron1993; Sokollek et al., Reference Sokollek, Hertel and Hammes1998; Steiner and Sauer, Reference Steiner and Sauer2001; Matsutani et al., Reference Matsutani, Ito, Azuma, Ogino, Shirai, Yakushi and Matsushita2015; Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019). So, the genomic landscape of AAB represents a plethora of challenges to be addressed to reach a stable and efficient BC production.

Therefore, it is questionable that BC can be assumed as a definitive solution for more sustainable manufacturing practices, despite the intellectual property protection efforts attempted in the recent years (Da Silva et al., Reference Da Silva, De Medeiros, De Amorim, Do Nascimento, Converti, Costa and Sarubbo2021). Another relevant limitation regarding the use of Komagataeibacter spp. is that only a limited fraction of their already identified proteins possess assigned functional categories (ca. 30% for K. xylinus E25 (Ryngajłło et al., Reference Ryngajłło, Kubiak, Jędrzejczak-Krzepkowska, Jacek and Bielecki2019). Such a lack of knowledge regarding protein function represents an opportunity for further exploration of proteomics (Zhang et al., Reference Zhang, Li and Nie2010).

Such instability represents a risk for prototyping research and the effort to get outside of the lab is substantial (Bernstein et al., Reference Bernstein, Reifschneider, Bennett and Wetmore2017). The only way to mitigate these risks is to increase the effort to decipher the genomic and biochemical details of AAB BC producers. Ultimately, only after that effort will be possible to obtain a standard framework to be utilised across disciplines and outside of the lab.

Bacterial cellulose and genetic engineering

Several attempts to genetically engineer AAB to generate higher yields of BC have also been investigated. Jang et al. (Reference Jang, Kim, Kim, Shim, Ryu, Park and Lee2019) engineered a K. xylinus strain and were able to more than double the yield of BC production (3.15 g/L) by overexpressing the heterologous pgi and gnd genes from Escherichia coli or Corynebacterium glutamicum. To increase the ability of K. xylinus to use mannose as a carbon source, Yang et al. (Reference Yang, Cao, Li, Chen, Wu, Zhou and Hong2023) engineered a strain capable of better using mannose-rich biomass as a sole carbon source through the expression of the mannose kinase (mak) and phosphomannose isomerase (pgi) genes from E. coli. Their results showed that the yield almost doubled while improving BC tensile strength and elongation potential. Since the yield is not the only feature relevant for BC generation, Huang et al. (Reference Huang, Liu, Sun, Li, Liu, Jia, Xie and Zhong2020) used the clustered regularly interspaced short palindromic repeats interference (CRISPRi) system to test and control the BC mechanical characteristics such as porosity and crystallinity by overexpressing the galU gene (responsible for controlling the carbon metabolic flux between BC synthesis and the pentose phosphate pathway). They found that the galU is positively associated with the BC crystallinity and negatively associated with the porosity. To allow a standard genetic engineering approach, Florea et al. (Reference Florea, Hagemann, Santosa, Abbott, Micklem, Spencer-Milnes, De Arroyo Garcia, Paschou, Lazenbatt, Kong, Chughtai, Jensen, Freemont, Kitney, Reeve and Ellis2016a) developed a modular toolkit to guide the genetic engineering of K. rhaeticus aiming for a high BC yield. Their toolkit works twofold, being applied to genetically engineer K. rhaeticus and applying extracted proteins to the BC itself. However, the toolkit is tailored specifically to this strain and optimised protocols must be tested to every other strain. Additionally, the BC mechanical properties (e.g. tensile, stiffness, viscoelasticity, porosity) have also to be studied to achieve a usable biomaterial (see Chen et al., Reference Chen, Lopez-Sanchez, Wang, Mikkelsen and Gidley2018, where they analysed the mechanical properties of six different Komagataeibacter strains, five K. xylinus and one K. hansenii).

Practical and industrial biodesign applications

To address the complex nature of BC, professionals are pushing the boundaries of knowledge, bringing other disciplines to their practice. Neri Oxman’s and Suzanne Lee’s works represent the next paradigm shift in biotechnological engineering, biofabrication, augmented architecture and biomaterials.

Oxman’s Aguahoja project focused on developing a robotic platform for 3D printing biomaterials, including cellulose (Duro-Royo et al., Reference Duro-Toyo, Zak, Ling, Tai, Hogan, Darweesh and Oxman2018). It is a 5-metre tall biocomposite structure, composed of several biopolymers such as BC. Aquahoja was developed through a computationally driven approach through additive manufacturing (Guzzi & Tibbitt, Reference Guzzi and Tibbitt2020), and its design was intended to allow temporality, being able to sense, inform the user of and adapt to changes in the surrounding ecosystem. The team behind Aquahoja found that shape and materiality are directly informed by physical properties (e.g. stiffness and opacity), environmental conditions (e.g. temperature and relative humidity) and fabrication technical constraints (e.g. arm speed and nozzle pressure). Such structure aims at optimised structural stability, flexibility and visual connectivity. Designed for biodegradability, Aquahoja’s exposure to environmental conditions like rainwater will disassemble its structure until its disappearance, giving back the biological building blocks to the natural nutrient cycle.

As a pioneer in merging biology and design, Suzanne Lee has been working on removing the boundaries within the two disciplines. As the CEO of BiofabricateFootnote ¹ (hosting, consulting and education company for biology-led innovation), she argues that “we have the tools to make the same things [as Nature] – without killing the animal, without cutting down the tree. We can programme biology to do it in a much more efficient way using minimal and renewable resources.”Footnote ² Suzanne Lee’s prediction is that the fourth industrial revolution will be a material one, led by biology. Developing BC-based fashion prototypes for 20 years she recalls that “the technology was absolutely right [20 years ago] but people just weren’t ready.”¹

Biodesigners have also explored BC as a design material. Carolina De Lara (Reference De Lara2024) developed BC-based composite textiles to be applied in footwear designs while defining the work methods tailored for designers with a non-biological background. Fiona Bell and colleagues developed an interactive breastplate biofabricated by SCOBY (Reference Bell, Chow, Choi and Alistar2023a) and a non-invasive bio-digital calendar that focus on the SCOBY’s well-being (Reference Bell, Coffie and Alistar2024). Ofer & Alistar (Reference Ofer and Alistar2023), created an immersive learning experience for biodesigning with kombucha. They focused on the sensory experience of designing with livingness and reporting through an autoethnographic research method. In practice, a lab journal was used for documentation, including writings on the reflective sensory engagement experience through the in-person contact with kombucha and SCOBY (sewing and embroidering, layering, laser cutting and engraving and moulding). Interestingly, Netta Ofer and Alistar (Reference Ofer and Alistar2023) offer a personal and non-scientifically take on growing BC while there is enough knowledge to grow it with more confidence: “how and when to feed it, what a healthy layer looks like, when a new layer should be expected, etc. All these nuances in the SCOBY’s growth were difficult to predict reliably, as each microbial culture and each grown layer had different behaviour and timeline. However, within that uncertainty, during the research team’s meetings, [Netta Ofer] would describe the growth from her own sensory point of view.” Reflecting about designing with living microorganisms is necessary but not sufficient; the current knowledge on growing AAB and SCOBY and producing BC cannot be neglected. Both can be achieved together. When not performed simultaneously, it constitutes an example of the need for a more robust interdisciplinarity approach.

Regarding the industrial and commercial applications, Polybion™Footnote ³ is a company that aims to source bio-based materials to the market, and Celium™ is their first biomaterial, formed by “premium cultivated cellulose.” Despite Polybion’s promises and media attention in the leather-alternatives’ sector, Celium’s features still requires further development before being presented as a more sustainable solution. This occurs because the material still requires a polyurethane coating for durability, and it works in combination with synthetic polymers. To achieve a more sustainable biomaterial, the approach must deviate from the reliance on petroleum-based plastics. It is urgent to explore other materials that do not hinder the biodegradability potential.

Consequently, the manufacture of BC is questionable and must be challenged in terms of its sustainable promises. The company assumes the compromise of durability in detriment of the biodegradability and sustainability by arguing that a long-lasting feature reduces frequent replacements, minimising waste generation and the associated environmental footprint (personal communication). The dilemma deserves a more critical view and justify the continue research and development of better solutions to assure the sustainability and durability of biomaterials. Interestingly, the product is already being marketed as a whole solution through a partnership with Gani,Footnote ⁴ while there are several questions to be answered. Therefore, the research purpose is to continue to elucidate, clarify and further explore the potential of novel solutions in addressing world problems (Popper, Reference Popper1959). Thus, biodesigners must take these cautionary notions into account when performing industrial-led briefings.

New curricula for biodesign

Questioning the participation of non-human organisms in research, Chen and Pschetz (Reference Chen and Pschetz2024) argue for a “microbial revolt.” To activate it they developed a workshop that “invites designers and biologists to reflect upon the invisible labour of lab organisms that support their research.” As often seen in BC experiments, contaminations hinder the laboratory work and increase the challenges for research. According to Chen and Pschetz (Reference Chen and Pschetz2024), microbial cell death and contaminations constitute microbial forms of resistance, refusal and non-cooperation to human activities. The workshop designs comprise the following steps:

1. i) Microbial embodiment and role-play;

2. ii) Journaling and group sharing;

3. iii) Artefacts/revolts creation (“Chindōgus”);

4. iv) Sketching/illustrating the results; and

5. v) Group sharing of the results.

By carrying out interviews with workshop participants, Chen and Pschetz (Reference Chen and Pschetz2024) were able to find bottlenecks to interdisciplinarity related to main themes such as the power dynamics inside the lab, care ecologies and research creative freedom. Such creative freedom can be tackled by blurring the boundaries between the learning, the making and the growing (Correa & Holbert Reference Correa and Holbert2021). Correa and Holbert (Reference Correa and Holbert2021) proposed the concept of “interspecies creative learning” that aims to foster the work with more-than-humans. So, their Myco-kit represents a biodesign toolkit to allow the learning and prototyping explorations for a more ecologically conscious practice. Despite being developed for young children, it may be potentially useful for older audiences. Therefore, by creating liminal spaces where those boundaries can be contested (Chen & Pschetz, Reference Chen and Pschetz2024), “interspecies creative learning” (Correa & Holbert, Reference Correa and Holbert2021) and creative discovery that respects the more-than-humans’ agency can potentially give rise to a more robust interdisciplinarity. Additionally, it can also be considered incorporating themes in the more-than-humans’ agenda like their temporalities (Oktay et al., Reference Oktay, Ikeya, Lee, Barati, Lee, Chen, Pschetz and Ramirez-Figueroa2023), representation as participatory decision makers,Footnote ⁵ values and perspectives (Bekker et al., Reference Bekker, Eriksson, Fougt, Hansen, Nilsson and Yoo2023) and engagement and embodying (Light, Reference Light2024).

Light (Reference Light2024) argues for “approaches that involve people in being-with, designing-with and participating-as non-humans” (p. 2). These three aspects should be inserted into the biodesign curriculum, to allow a more non-anthropogenic curriculum. This calls for more creative tools to be explored, such as imagination – “imagination is invoked to bring in non-human actors; the humans ‘becoming’ other beings to do tasks.” (Light, Reference Light2024, p. 3). Assuming that it is challenging to speak of or from the more-than-humans’ experience, the exercise stimulates different non-human perspectives and phenomenological possibilities. At least, biodesigners need improved and complete design representations, that allow the development of more representative biological metaphors encompassing the appropriate more-than-humans’ agency (Dade-Robertson & Zhang, Reference Dade-Robertson and Zhang2024).

Bekker et al. (Reference Bekker, Eriksson, Fougt, Hansen, Nilsson and Yoo2023) defined challenges in teaching more-than-human perspectives in the field of Human-Computer Interactions. Despite not being directly aimed at biodesigners, the focus on practitioners coming from non-biological backgrounds can relate to design as well. They defined three main themes relevant to the more-than-humans’ perspectives: species, things and designers, and from their experience, the identified challenges are (Bekker et al., Reference Bekker, Eriksson, Fougt, Hansen, Nilsson and Yoo2023, p. 57):

1. i) Representation: “who might speak on behalf of whom”;

2. ii) Inclusion: “how can students make sure to include all the relevant perspectives – including the more-than-human”;

3. iii) Human and non-human designers: “if the designer is a non-human (…) how might this influence the design process”;

4. iv) Outcome and effect: “what are the success criteria for working on a project with more-than-human players”;

5. v) Role of (bio) technology: “if/how/when technologies are necessary, or whether it is more fruitful to develop tools with no technologies involved”;

6. vi) Bias: how to go beyond “western thinking, and the hegemony of modernist paradigms (…) to bring in perspectives from other cultures that are more aligned with a more-than-human ecological worldview” (p. 57).

The use of biological probes can facilitate and enhance the experience of teaching and learning biodesign maintaining the care for the more-than-perspectives. Briefly, biological probes “are intended to provide the setting in which it is possible to engage with biological systems from a design perspective” (Ramirez-Figueroa, Reference Ramirez-Figueroa2017, p. 8). They allow the engagement with other organisms and their phenotypes. Therefore they:

1. i) Enable open-ended, non-deterministic design outcomes;

2. ii) Operate within rigorous domains and objectives;

3. iii) Articulate throughout direct engagements with living systems and;

4. iv) Operate as inspirations for critical thinking.

Ultimately, the deployment of biological probes can extend the biodesign teaching practice outside of the lab and formal educational spaces. As Chappell et al. (Reference Chappell, Perez and Okada Takara2023) observed, “informal learning spaces can empower multidirectional and multigenerational knowledge exchange and advance a more diverse, inclusive, and innovative biodesign enterprise” (p. 1). Their work shows the benefits of biodesign education in bringing other actors. Artists, teachers, activists and researchers can activate creativity, playfulness, storytelling and ancestral scientific knowledge in informal learning spaces such as community bio-labs, summer camps and art-based maker spaces (Chappell et al., Reference Chappell, Perez and Okada Takara2023).