Alternative Sugar Research Articles

Biomass Demineralization and Pretreatment Strategies to Reduce Inhibitor Concentrations in Itaconic Acid Fermentation by Aspergillus terreus

Itaconic acid (IA) is a platform chemical, derived from non-petroleum sources, produced through the fermentation of glucose by Aspergillus terreus. However, producing IA from alternative sugar sources (e.g., lignocellulose) has been shown to be problematic, requiring post-hydrolysis mitigation to allow growth and IA production by the fungus. It is well known that the side products of lignocellulosic biomass conversion to sugars act as microbial growth inhibitors. An uncommon feature of fungal organic acid fermentations is production inhibition caused by mineral ions in biomass hydrolysate after pretreatment and enzymatic hydrolysis. To minimize mineral introduction during pretreatment and hydrolysis, we determined the sources of growth and production inhibitors at each of these steps. Biomass demineralization and four pretreatment strategies were evaluated for inhibitor introduction. Dilution assays determined the approximate degree of inhibition for each hydrolysate. An ammonium hydroxide pretreatment of demineralized wheat straw presented the lowest concentration of inhibitors and concomitant lowest inhibition: subsequent fermentations produced 35 g L−1 IA from wheat straw hydrolysate (91 g L−1 sugar) without post-hydrolysis mitigation.

Reduction in mutualistic ant aggressive behavior upon sugar supplementation

AbstractMutualistic interactions between species are widespread and important for community structure and ecosystem function. In a changing environment, the proximate mechanisms that maintain mutualisms affect their stability and susceptibility to perturbation. In ant‐plant mutualisms, ants defend their host plants against herbivores or competing plants in exchange for housing or food. While the phenomenon of species exchanging services for resources is well documented, how such arrangements are maintained is not. There are at least four hypothesized mechanisms through which plants use sugar to induce ant defense against herbivores. Three such hypotheses (“deficit”, “fuel for foraging”, “predictable rewards”) predict that the appearance of a new sugar source near the host plant would increase the rate of ant attacks against herbivores, but the fourth hypothesis (“attract and distract”) predicts the opposite. To examine how the mutualism between Triplaris americana and Pseudomyrmex dendroicus would be affected, we simulated the appearance of a novel sugar source at a random half of 34 T. americana trees with P. dendroicus colonies. Compared to control colonies, those with access to the sugar source were less likely to attack herbivorous insects (Nasutitermes sp. termites). Thus, our findings support the “attract and distract” hypothesis. We infer that this ant‐plant mutualism could be destabilized by the appearance of an alternative sugar source, such as a nectar‐producing plant or honeydew‐excreting insect. More broadly, we conclude that the mechanisms responsible for maintaining mutualistic relationships are relevant for understanding how ecological communities are affected by environmental change.Abstract in Spanish is available with online material.

Blooming calendar and polliniferous plants in Djuanda Great Forest Park, West Java, Indonesia: Implication for beekeeping management

Abstract. Husodo T, Wulandari I, Saputri Y, Kasmara H, Hermawan W, Kusmoro J, Shanida SS, Khairina F, Haydar MRA, Asyraf MN, Febrian RR. 2024. Blooming calendar and polliniferous plants in Djuanda Great Forest Park, West Java, Indonesia: Implication for beekeeping management. Biodiversitas 25: 3216-3229. Information was unavailable regarding the types of pollinator plants and their blooming periods in Djuanda Great Forest Park, West Java, Indonesia. Information about flower blooming seasons was useful for various purposes. These findings will provide a basis for understanding the importance of Apis cerana Fabricius, 1793 in plant pollination and plant species resources for honey bees so that beekeeping practices can be carried out sustainably. The blossoming period of a plant is determined by its blooming period at the time of observation. The blooming period is observed every month in the second and fourth weeks for six months (December 2021-May 2022). Pollen collection was carried out in August 2021 (dry season). Pollen identification was carried out using the acetolysis method, which involves dissolving the non-pollen components of a sample to reveal the pollen grains, thereby enabling accurate identification. An overview of the observation records revealed the presence of 249 plant species from 82 families. The Asteraceae family has the most abundant species richness. Most plants were identified as pollinator plants (30.52%), nectariferous plants (10.04%), and plants that produce both (18.47%). Flowering plants of melliferous plants for honeybees are available throughout the rest of the year, especially from December to May. Therefore, to optimize honey harvesting, it is important to establish multiple colonies during periods of large honey flows. Honeybees may use alternative sugar sources beekeepers provide, such as fruit juice, during nectar scarcity. We would like to know more about the year-round bloom calendar. Sharing knowledge with farmers about the availability of melliferous plants in certain months will empower them to make decisions for sustainable beekeeping.

Impact of Rare Sugar D-Allulose on Hardening of Starch Gels during Refrigerated Storage.

The rare sugar D-allulose (Alu), with ca. 10% calories of sucrose (Suc), is a promising alternative sugar that can be used to improve the quality of starch gels in storage. The effects of Alu (compared to Suc) on the hardening and microstructural and molecular order of amylopectin-rich (glutinous rice (GR) and corn amylopectin (CAP)) and amylose-rich (corn (C)) starch gels were investigated. Alu and Suc both suppressed hardening in C gels, while Alu but not Suc was effective in GR and CAP gels. SEM results showed that Alu-containing GR and CAP maintained a relatively large pore size compared to Suc-containing gels. The deconvolution of FTIR spectra revealed that Alu-containing GR and CAP gels had lower ratios of intermolecular hydrogen bonds and higher ratios of loose hydrogen bonds than Suc-containing gels. For amylose-rich C gels, on the other hand, such tendencies were not observed. The influence of Alu on amylopectin-rich gels could be because Alu reduced the ratio of intermolecular hydrogen bonds, which might be involved in amylopectin recrystallization, and increased that of loose hydrogen bonds. The results suggest that Alu is more effective than Suc in inhibiting the hardening of amylopectin-rich starch gels during refrigerated storage.

Glucose Syrup from Purple Sweet Potatoes (Ipomoea batatas L. Poir) using Acid Hydrolysis Method

<p><strong>Abstract.</strong> The making of glucose syrup from purple sweet potatoes is motivated by the high demand for alternative sugar in Indonesia. Through the processes that have been carried out and the results of previous studies, the potential of purple sweet potatoes to be processed into glucose syrup has been produced. This experiment was conducted to determine whether purple sweet potatoes can be processed into glucose syrup and to determine the suitability of the product to the standard. To convert purple sweet potatoes into glucose syrup, it is necessary to first extract the starch content in purple sweet potatoes and go through the process of making glucose syrup by the acid hydrolysis method using citric acid of various concentrations (0.2, 0.4, 0.6, 1 N). For the feasibility of consuming glucose syrup from purple sweet potatoes, a toxicity test was carried out using the Brine Shrimp Lethality Test (BSLT) method. Tests were also carried out on water, ash, reducing sugar, and starch content to then be compared with the Indonesian glucose syrup standard (SNI 01-2978-1992). The results showed that the reducing sugar content of purple sweet potato glucose syrup followed the glucose syrup quality standard, which was 43.31%, the lowest water content was 18.35%, the lowest ash content was 7.95% and there was no starch content in purple sweet potato liquid sugar. The aroma of the glucose syrup produced was following the Indonesian National Standard, but the color and taste produced were not yet in accordance. The toxicity test of purple sweet potato liquid sugar showed a lethal concentration value of LC<sub>50</sub> >1,000 ppm, which means that purple sweet potato liquid sugar has no toxic potential so it is safe for consumption.</p><p><strong>Keywords:</strong></p><p>Purple Sweet Potatoes, Liquid Sugar, Acid Hydrolysis</p><p><strong><br /></strong></p>

Impact of artificial sweeteners and rare sugars on the gut microbiome.

Alternative sugars are often used as sugar substitutes because of their low calories and glycemic index. Recently, consumption of these sweeteners in diet foods and beverages has increased dramatically, raising concerns about their health effects. This review examines the types and characteristics of artificial sweeteners and rare sugars and analyzes their impact on the gut microbiome. In the section on artificial sweeteners, we have described the chemical structures of different sweeteners, their digestion and absorption processes, and their effects on the gut microbiota. We have also discussed the biochemical properties and production methods of rare sugars and their positive and negative effects on gut microbial communities. Finally, we have described how artificial sweeteners and rare sugars alter the gut microbiome and how these changes affect the gut environment. Our observations aim to improve our understanding regarding the potential health implications of the consumption of artificial sweeteners and low-calorie sugars.

Physicochemical Characteristics of Bitter Leaf (Vernonia amygdalina Del.) Kombucha with Palm Sugar Addition

Functional drinks are processed drinks that contain food components that are beneficial for body health and have good sensory evaluation. Functional drinks can be used to prevent degenerative diseases such as diabetes mellitus. Kombucha is a functional drink fermented from tea and sugar using a kombucha starter or Symbiotic Culture of Bacteria and Yeast (SCOBY). Kombucha has functions as an antioxidant, antidiabetic, anticancer and antimicrobial. A variety of leaves that include phenols and bitter leaves with components that are beneficial to the body can be used to make kombucha. Palm sugar can be used as alternative sugar for kombucha fermentation because palm sugar has a low glycemic index of 35. This study aims to determine the effect of using palm sugar concentration on total dissolved solids, viscosity, pH value, total flavonoids, total phenols, and reducing sugar content. The research results show that the use of palm sugar can increase total dissolved solids, viscosity, pH value, total flavonoids, total phenols and reducing sugars. The best treatment is the use of 25% palm sugar with a total soluble solids value of 18.38˚Brix, viscosity of 1.37 cP, pH value of 3.43, total flavonoids of 0.275 mg QE/g sample, total phenols of 0.99 mg GAE/ml, and reducing sugar of 9.24%.

D-Tagatose: A Rare Sugar with Functional Properties and Antimicrobial Potential against Oral Species.

Carbohydrates have a dietary role, but excessive consumption of high-calorie sugars can contribute to an increased incidence of metabolic diseases and dental caries. Recently, carbohydrates with sweetening properties and low caloric value, such as D-tagatose, have been investigated as alternative sugars. D-tagatose is a rare sugar that has nutritional and functional properties of great interest for health. This literature review presents an approach to the biological effects of D-tagatose, emphasizing its benefits for oral health. Studies report that D-tagatose has antioxidant and prebiotic effects, low digestibility, reduced glycemic and insulinemic responses, and the potential to improve the lipid profile, constituting an alternative for diabetes mellitus and obesity. It can also be observed that D-tagatose has an antioxidant action, favoring the elimination of free radicals and, consequently, causing a reduction in cellular oxidative stress. Furthermore, it also has antibacterial potential against oral species. Regarding oral health, studies have shown that D-tagatose efficiently reversed bacterial coaggregations, including periodontopathogenic species, and impaired the activity and growth of cariogenic bacteria, such as S. mutans. D-tagatose significantly inhibited biofilm formation, pH decrease and insoluble glucan synthesis in S. mutans cultures. Salivary S. mutans counts were also significantly reduced by the consumption of chewing gum containing D-tagatose and xylitol. In addition, there is evidence that tagatose is effective as an air-polishing powder for biofilm decontamination. The literature indicates that D-tagatose can contribute to the prevention of systemic diseases, also constituting a promising agent to improve oral health.

Potensi Dan Prospek Industri Gula Aren Di Indonesia

Palm sugar produced from sugar palm plants is an alternative sugar to granulated (refinery) sugar produced from sugar cane plants. Recently, more and more consumers are switching from granulated sugar to palm sugar. However, because entrepreneurs are still traditional, efforts to meet changing consumer tastes still have many obstacles. This research aims to (1) determine the potential of sugar palm plants as; (2) analyze the prospects for the Indonesian small palm sugar industry in the future. The method for determining the research location was carried out purposively, namely the Republic of Indonesia, which is one of the largest palm sugar producers in the world. This research was carried out from March 2024 to May 2024. This research was carried out using a survey approach and used secondary data, especially BPS publication data. To find out the prospects for palm sugar in Indonesia, it is explained using simple linear regression. Meanwhile, the analysis of plant potential is explained descriptively qualitatively and quantitatively. The research results show that sugar palm cultivation in Indonesia has great potential, especially because sugar palm plants do not require complicated growing requirements. Almost all areas in Indonesia can be planted with palm trees. The availability of land in Indonesia is quite extensive, has hydrological and conservative functions. There is a traditional farming culture in cultivating palm sugar. The results of regression analysis using time series data from 1992 to 2020 show that the development of land area, which is a manifestation of farmers' response to demand for palm sugar, shows an increasing trend. With ß of 1,046.5, it shows that on average every year there is an increase in the area of ​​sugar palm plantations of 1,046.5. Meanwhile, from the production aspect, the results of the regression analysis also show a significant increasing trend with ß of 2,575.4, which shows that from the production aspect there has been a significant increase in production, namely 2,575.4 tonnes each year. Furthermore, it can be concluded that the potential for palm tree development is quite good and the prospects for the palm sugar industry in Indonesia are quite bright.

A correlative study of the genomic underpinning of virulence traits and drug tolerance of Candida auris.

Candida auris is an opportunistic fungal pathogen with high mortality rates which presents a clear threat to public health. The risk of C. auris infection is high because it can colonize the body, resist antifungal treatment, and evade the immune system. The genetic mechanisms for these traits are not well known. Identifying them could lead to new targets for new treatments. To this end, we present an analysis of the genetics and gene expression patterns of C. auris carbon metabolism, drug resistance, and macrophage interaction. We chose to study two C. auris isolates simultaneously, one drug sensitive (B11220 from Clade II) and one drug resistant (B11221 from Clade III). Comparing the genomes, we confirm the previously reported finding that B11220 was missing a 12.8 kb region on chromosome VI. This region contains a gene cluster encoding proteins related to alternative sugar utilization. We show that B11221, which has the gene cluster, readily assimilates and utilizes D-galactose and L-rhamnose as compared to B11220, which harbors the deletion. B11221 exhibits increased adherence and drug resistance compared to B11220 when grown in these sugars. Transcriptomic analysis of both isolates grown on glucose or galactose showed that the gene cluster was upregulated when grown on D-galactose. These findings reinforce growing evidence of a link between metabolism and drug tolerance. B11221 resists phagocytosis by macrophages and exhibits decreased β-1,3-glucan exposure, a key determinant that allows Candida to evade the host immune system, as compared to B11220. In a transcriptomic analysis of both isolates co-cultured with macrophages, we find upregulation of genes associated with transport and transcription factors in B11221. Our studies show a positive correlation between membrane composition and immune evasion, alternate sugar utilization, and drug tolerance in C. auris.

Manipulated ants: inducing loyalty to sugar feeders with an alkaloid.

Wood ants are promising biocontrol agents in fruit plantations because they prey on pest insects and inhibit plant diseases. However, these ants also attend plant-feeding homopterans to harvest their honeydew secretions, thereby increasing their numbers. This problem can be solved by offering ants alternative sugar sources that are more attractive than honeydew. From natural interactions, it is known that some species manipulate mutualistic partners toward loyalty by adding alkaloids to the food they offer their mutualists. Inspired by this, the addition of alkaloids might be used to make ants loyal to artificial sugar feeders and thus used to reduce populations of ant-farmed homopterans in ant-mediated biological control. We aimed to explore whether wood ants (Formica polyctena) would develop a taste preference for morphine-containing sugar solutions in two-choice laboratory tests. After having fed on a morphine/sugar solution for 1 week, ants showed a significant preference for morphine solutions compared with equal concentration sugar solutions without morphine. Furthermore, ants lost this preference after 6-9 days on a morphine-free diet. The results show that wood ants react to morphine in their food, enabling chemical manipulation of their behavior, most likely through a taste preference. Thus, ants are susceptible to manipulation by mutualistic partners in natural interactions and furthermore may be manipulated artificially in biocontrol programs to avoid ant-mediated build-up of homopteran populations. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plant-Growth-Promoting Rhizobacteria Modulate Carbohydrate Metabolism in Connection with Host Plant Defense Mechanism.

Plant-growth-promoting rhizobacteria (PGPR) could potentially enhance photosynthesis and benefit plant growth by improving soil nutrient uptake and affecting plant hormone balance. Several recent studies have unveiled a correlation between alterations in photosynthesis and host plant resistance levels. Photosynthesis provides materials and energy for plant growth and immune defense and affects defense-related signaling pathways. Photosynthetic organelles, which could be strengthened by PGPR inoculation, are key centers for defense signal biosynthesis and transmission. Although endophytic PGPRs metabolize plant photosynthates, they can increase soluble sugar levels and alternate sugar type and distribution. Soluble sugars clearly support plant growth and can act as secondary messengers under stressed conditions. Overall, carbohydrate metabolism modifications induced by PGPR may also play a key role in improving plant resistance. We provide a concise overview of current knowledge regarding PGPR-induced modulation in carbohydrate metabolism under both pathogen-infected and pathogen-free conditions. We highlight PGPR application as a cost-saving strategy amidst unpredictable pathogen pressures.

Valorisation of chewing gum production waste in bioethanol production: a response surface methodology study

ABSTRACT Interest in fast-moving consumer goods (FMCG) is constantly growing all over the world. Chewing gum, which is in the group of pleasant and entertaining snacks preferred by people of all ages, especially children and young people, is one of the most consumed products in the food sector. Due to its remarkable production and the major components, chewing gum waste has the potential as an alternative sugar source for bioethanol production. To evaluate bioethanol production from chewing gum wastes, the sugar was first extracted, and directly fermented into ethanol under different conditions. Saccharomyces cerevisiae (fresh and dry) and Saccharomyces bayanus were used as the yeast. To determine the optimal fermentation medium, the response surface methodology (RSM) study was employed and the fermentation medium variables were tested such as agar, pepton and glucose (APG medium) concentrations. The APG medium in which the maximum bioethanol yield obtained was determined as 5 g/L agar, 10 g/L peptone and 5 g/L glucose. The highest ethanol yield under optimal APG medium was obtained as 9.1-4 g ethanol/L sugar after 72 h by using Saccharomyces cerevisiae (fresh). The obtained results showed that chewing gum wastes can be utilised a potential source for the bioethanol production.

Use of coconut sugar as an alternative agent in osmotic dehydration of strawberries.

This study aimed to evaluate coconut sugar (CS) as an alternative osmotic agent to sucrose for the osmotic dehydration (OD) of strawberries. OD was performed by immersing strawberries cut into 13.6±0.4mm edge cubes in osmotic solutions of CS or sucrose, at two different concentrations (40% and 60%, w/w), with and without application of vacuum (AV) in the first 20min of the process. The total OD time was 300min. Evaluations of the kinetics of solid gain (SG), water loss (WL), and weight reduction (WR) were performed at 30, 60, 120, 180, 240, and 300min. SG, WL, and WR increased over the OD time and showed values of up to 7.94%, 63.40%, and 55.94%, respectively. AV increased WL, WR, shrinkage, pH, and total color difference and decreased anthocyanin, ascorbic acid (AA), phenolic, and antioxidant contents. The higher concentration led to higher SG, WL, WR, shrinkage, hardness, and lower moisture content, water activity, anthocyanin, AA, phenolic, and antioxidant contents. The use of CS instead of sucrose had little influence on strawberry properties, except pH and color responses. The optimal treatment was using a 60% CS solution without AV, showing a very distinct color change, hardness increased by approximately 4.5 times and maintenance of acidity, anthocyanins, AA, total phenolics, and antioxidants of 38.0%, 39.6%, 11.8%, 30.0%, 31.1%, and 30.3%, respectively, compared to fresh strawberries. PRACTICAL APPLICATION: Osmotic dehydration of fruit is a process traditionally carried out using sucrose. However, increasing health concerns have made consumers seek alternative sugars to sucrose. The use of coconut sugar made it possible to produce osmo-dehydrated strawberries different from the traditional one, maintaining product quality and process efficiency.

Bioprospeksi Bunga Lolipop (Pachystachys lutea Nees) sebagai Sumber Alternatif untuk Produksi Gula

The lollipop plant (Pachystachys lutea Nees) has been known as an ornamental plant species that originated from the South America region. In Indonesia, some local children claim that the nectar of this flower has a very sweet flavor. This fact has inspired this short bioprospecting study of the lollipop plant with aim to discover its nectar as a potential alternative sugar source. The study was conducted in Bandung, West Java, Indonesia. Four lollipop plants from three different shading level (one plant in full shade andpartial shade, and two plant in full sun exposure) were sampled as many as five flowers from each plant and their nectar droplets, measured using brix refractometer, and also compared with sweet corn seeds (Zea mays L.) and sugarcane stems (Saccharum officinarum L.). The data was then validated for its significance using t-Tests. The result shows that the lollipop plant grown in partial shade has the highest brix percentage (27.00±1.02%) compared to the rest and is significantly different statistically. The brix percentage of all samples combined for this lollipop plant (25.56±0.42%) also surpassed the sugarcane (15.33±0.36%) and sweet corn (12.67±0.47%) and was significantly different statistically.

Divergence of alternative sugar preferences through modulation of the expression and activity of the Gal3 sensor in yeast.

Optimized nutrient utilization is crucial for the progression of microorganisms in competing communities. Here we investigate how different budding yeast species and ecological isolates have established divergent preferences for two alternative sugar substrates: Glucose, which is fermented preferentially by yeast, and galactose, which is alternatively used upon induction of the relevant GAL metabolic genes. We quantified the dose-dependent induction of the GAL1 gene encoding the central galactokinase enzyme and found that a very large diversification exists between different yeast ecotypes and species. The sensitivity of GAL1 induction correlates with the growth performance of the respective yeasts with the alternative sugar. We further define some of the mechanisms, which have established different glucose/galactose consumption strategies in representative yeast strains by modulating the activity of the Gal3 inducer. (1) Optimal galactose consumers, such as Saccharomyces uvarum, contain a hyperactive GAL3 promoter, sustaining highly sensitive GAL1 expression, which is not further improved upon repetitive galactose encounters. (2) Desensitized galactose consumers, such as S. cerevisiae Y12, contain a less sensitive Gal3 sensor, causing a shift of the galactose response towards higher sugar concentrations even in galactose experienced cells. (3) Galactose insensitive sugar consumers, such as S. cerevisiae DBVPG6044, contain an interrupted GAL3 gene, causing extremely reluctant galactose consumption, which is, however, improved upon repeated galactose availability. In summary, different yeast strains and natural isolates have evolved galactose utilization strategies, which cover the whole range of possible sensitivities by modulating the expression and/or activity of the inducible galactose sensor Gal3.

Molecularly imprinted electrochemical sensor for highly selective and sensitive determination of artificial sweetener Acesulfame-K

The excess use of artificial sweeteners poses a serious issue to the environment and human health. Acesulfame-K (Ace-K) is a non-nutritive artificial sweetener excessively used as an alternative sugar substitute in various foods and beverages. Here a simple, selective and rapid method to determine Ace-K in dietary products is proposed. In this study, a molecularly imprinted polymer (MIP) based electrochemical sensor is designed for the sensitive and selective determination of Ace-K. MIP was developed by the electropolymerization of ortho-phenylenediamine (o-PD) thin film around template molecules (Ace-K) on a glassy carbon electrode. Various parameters such as deposition cycle, template removal and rebinding parameters were optimized for sensor fabrication. The sensor was characterized after each stage of fabrication using cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM) analysis. The MIP sensor exhibited wide linear range for the determination of Ace-K from 0.1 to 17.0 μM. The developed sensor attained the limit of detection (LOD) and limit of quantification (LOQ) of 0.35 µM and 1.2 µM, respectively. The applicability of the proposed sensor was examined for Ace-K determination in real samples. The MIP sensor exhibited excellent selectivity, repeatability, stability and commercialization potential for Ace-K detection.

Condition and Honey Productivity of Honeybee Colonies Depending on Type of Supplemental Feed for Overwintering.

Harvested honey is usually replaced by an alternative sugar to overwinter honeybee colonies. Supplementation of winter stores with beet or cane sucrose is safe for colonies and does not cause winter mortality. Despite this, there are hypotheses that supplementation of inverted sugars has the potential to give better results in overwintering, spring growth, and honey production of the colonies, because bees are consuming already cleaved feed. Therefore, we compared the condition parameters and honey production in 70 colonies at four apiaries overwintered with stores from sucrose or inverted sugars. No statistically significant differences in dependence on the type of the supplemental feed were found. Inverted sugar was more expensive than sucrose for feeding colonies. Economic efficiency, physiological consequences, and other disadvantages of using invert syrups are discussed.

Characterization and Mycotoxin Screening of Fungal Isolates from Palm Sugar

The global demand for alternative sugars is rising due to their lower glycemic index and other health benefits. However, improper manufacture, processing, transport, export, and/or marketing of regional sugar products increases the risk of microbial infection upon consumption. Fungal exposure and contamination of alternative sugars may occur as a result of enhanced hygroscopicity of certain sugar forms such as coconut and palm sugars, which strongly attract water molecules to their surface and thereby fungal spores, a property affected by adulteration practices, e.g. incorporation of cane sugar. The present study highlights risks of unregulated processing of palm sugar in the form of fungal contaminants and their toxigenic potential. Palm sugar was sampled for fungal isolates which were identified as Aspergillus flavus, A. niger, A. carbonarius, A. terreus, and A. fumigatus, followed by colony enumeration. Subsequent extraction of fungal extracts by thin layer chromatography resulted in detection of mycotoxins, including aflatoxins B1 and G1, citrinin, and ochratoxin. The findings confirmed that humid conditions may be optimal for the presence of toxigenic fungi in the palm sugar and production of toxic metabolites, indicating that more stringent regulation is required for palm sugar processing, as the toxins can lead to detrimental health consequences, including acute poisoning, nephropathy, and liver cancer.

A synthetic C2 auxotroph of Pseudomonas putida for evolutionary engineering of alternative sugar catabolic routes

Acetyl-coenzyme A (AcCoA) is a metabolic hub in virtually all living cells, serving as both a key precursor of essential biomass components and a metabolic sink for catabolic pathways for a large variety of substrates. Owing to this dual role, tight growth-production coupling schemes can be implemented around the AcCoA node. Building on this concept, a synthetic C2 auxotrophy was implemented in the platform bacterium Pseudomonas putida through an in silico-informed engineering approach. A growth-coupling strategy, driven by AcCoA demand, allowed for direct selection of an alternative sugar assimilation route—the phosphoketolase (PKT) shunt from bifidobacteria. Adaptive laboratory evolution forced the synthetic P. putida auxotroph to rewire its metabolic network to restore C2 prototrophy via the PKT shunt. Large-scale structural chromosome rearrangements were identified as possible mechanisms for adjusting the network-wide proteome profile, resulting in improved PKT-dependent growth phenotypes. 13C-based metabolic flux analysis revealed an even split between the native Entner-Doudoroff pathway and the synthetic PKT bypass for glucose processing, leading to enhanced carbon conservation. These results demonstrate that the P. putida metabolism can be radically rewired to incorporate a synthetic C2 metabolism, creating novel network connectivities and highlighting the importance of unconventional engineering strategies to support efficient microbial production.