Two-stage process production of microbial lipid by co-fermentation of glucose and N-acetylglucosamine from food wastes with Cryptococcus curvatus

Highly-efficient co-production of microbial lipid and magnesium ammonium phosphate from N-acetyl-D-glucosamine

The valorization of chitin-rich wastes into chemicals and biofuels holds immense economic and environmental benefits. Here, N-acetyl-D-glucosamine (GlcNAc), the basic structural unit of chitin, was firstly described for co-producing microbial lipid and magnesium ammonium phosphate (MAP). Due to the strong substrate inhibition of GlcNAc, a fed-batch culture mode was successfully adopted to achieve high cell density by Cutaneotrichosporon oleaginosum. When a phosphate limitation strategy was applied, cell mass, lipid titer, content, yield, and productivity were 102.7 g/L, 74.2 g/L, 72.2 %, 21.4 g/100 g, and 0.69 g/L/h, respectively. The ammonium ion was efficiently precipitated by forming MAP with a removal rate around 95.4 %. The lipid samples showed high similarity to vegetable oil, which emerged as high-quality precursor for biodiesel production. This study offers a promising strategy for full conversion of GlcNAc into lipid and slow-release fertilizer, which provides an attractive technical route for turning the chitin-rich materials into valuable products.

Non-sterile cultivation of oleaginous organisms

Cultivating oleaginous organisms in non-sterile conditions can reduce the energy and cost of microbial oil production. Recent studies use strategies that enable non-sterile cultivation without affecting bioprocess productivity. This forum article discusses the trends, strategies, and prospects of non-sterile cultivation, as successful non-sterile cultivation could make microbial oil production economically viable.

Turning food waste to microbial lipid towards a superb economic and environmental sustainability: An innovative integrated biological route

With the drastic growth of the economic and population, the global energy requirement is on the rise, and massive human and material resources have been put into the development of alternative and renewable energy sources. Biodiesel has been recognized as a green and sustainable alternative energy, but the raw materials-associated source and cost makes it difficult to achieve large-scale commercial production. Microbial lipids (ML) produced by oleaginous microbes have attracted more and more topics as feedstocks for biodiesel production because of their unique advantages (fast growth cycle, small footprint and so on). However, there are still many problems and challenges ahead towards commercialization of ML-based biodiesel, especially the cost of feedstock for ML production. Food waste (FW) rich in organic matters and nutrients is an excellent and almost zero-cost feedstock for ML production. However, current biological routes of FW-based ML production have some defects, which make it impossible to achieve full industrialization at present. Therefore, this review intends to provide a critical and comprehensive analysis of current biological routes of FW-based ML production with the focus on the challenges and solutions forward. The biological routes towards future FW-based ML production must be able to concurrently achieve economic feasibility and environmental sustainability. On this condition, an innovative integrated biological route for FW-based ML production has thus been put forward, which is also elucidated on its economic and environmental sustainability. Moreover, the prospective advantages, limitations and challenges for future scale-up of FW-based ML production have also been outlined, together with the perspectives and directions forward.

Comprehensive Exploration of the Growth and Lipid Synthesis Phases of T. oleaginosus Cultures Implementing Design of Experiments and Response Surface Methodology

Trichosporon oleaginosus is an unconventional oleaginous yeast distinguished by its remarkable capacity to accumulate lipids in excess of 70% of its dry weight, particularly when cultivated in nitrogen-restricted conditions with ample carbon sources. A pivotal question that arises pertains to the nutrient dynamics in the culture medium, which give rise to both the excessive lipid content and corresponding lipid concentration. While previous research has predominantly focused on evaluating the impact of the initial carbon-to-nitrogen (C/N) ratio on lipid production, the precise critical thresholds of glucose and ammonium sulfate ((NH4)2SO4) at which growth and intracellular lipid production are either stimulated or impeded remain inadequately defined. This study employs an experimental design and response surface methodology to investigate the complex mechanism of lipid accumulation and its interaction with cellular growth. Application of the aforementioned methodologies resulted in the production of 10.6 g/L of microbial oil in batch cultures under conditions that correspond to a C/N ratio of 76. However, the primary objective is to generate knowledge to facilitate the development of efficient fed-batch cultivation strategies that optimize lipid production exclusively employing inorganic nitrogen sources by finely adjusting carbon and nitrogen levels. The intricate interaction between these levels is comprehensively addressed in the present study, while it is additionally revealed that as glucose levels rise within a non-inhibitory range, lipid-free biomass production decreases while lipid accumulation simultaneously increases. These findings set the stage for further exploration and the potential development of two-stage cultivation approaches, aiming to fully decouple growth and lipid production. This advancement holds the promise of bringing microbial oil production closer to commercial viability.