Microbial Research Articles

The effect of rosemary, ginger, or garlic on microbial shelf life and sensory acceptability of nutritionally enriched cassava-based pancake (Kabalagala)

Iron and vitamin A contents of Cassava-based pancake (Kabalagala), a delicacy among children in northern Uganda have recently been improved through the addition of biofortified iron-rich beans and orange-fleshed sweet potato. The nutritionally improved product (NIK) was designed as a strategy to address iron and vitamin A deficiencies which are endemic challenges among children in Uganda. However, the NIK had a lower microbial shelf life (24 hours) than the original product (72 hours). The objective of this study was to investigate the potential of the spices; rosemary, ginger, and garlic to improve the microbial shelf life of the NIK. Each of the spices was used individually to prepare NIK at a rate of 0.5, 0.75, and 1%. The resultant products were evaluated for counts of total microbial load, Enterobacteriaceae, lactic acid bacteria, yeasts and molds as well as consumer sensory acceptability during storage at ambient temperature. Results of One-way Analysis of Variance (ANOVA) showed that all the spices exhibited potency against the microbial groups investigated only when included in the NIK at 0.75% or 1% (p<0.05). The microbial shelf life of the NIK based on total microbial count increased from 24 to 72 hours depending on the spice type and concentration. The spice, 1% ginger resulted in Enterobacteriaceae and yeast and molds counts within acceptable microbial threshold for the entire storage time (72 hours) with a maximum load of 3.41 and 2.82 log10 CFU/g, respectively. The NIK containing ginger or garlic at 0.75 or 1%, was more accepted and the extent of acceptability increased with storage time (p<0.05). Based on the overall acceptability, the consumer acceptability varied from 1% garlic > 0.75% garlic > 1% ginger > 0.75% ginger > 0.5% ginger in decreasing order. Spearman's correlation analysis revealed a strong association between the sensory parameters examined (appearance, aroma, texture, taste) and the overall acceptability of the products (p<0.05). The magnitude of association between appearance, aroma, texture, taste and overall acceptability varied between 0.396-0.703, 0.504-0.679, 0.452-0.589, and 0.498-0.698, respectively. This study has demonstrated that ginger or garlic when applied at 0.75-1% improves microbial shelf life of NIK concomitant with better consumer sensory acceptability. Therefore, ginger or garlic can be applied at 0.75-1% to produce microbiologically and sensorially acceptable NIK for use to improve intake of vitamin A and iron among children in Uganda.

Microbial central carbon metabolism in a tidal freshwater marsh and an upland mixed conifer soil under oxic and anoxic conditions.

The central carbon (C) metabolic network is responsible for most of the production of energy and biosynthesis in microorganisms and is therefore key to a mechanistic understanding of microbial life in soil communities. Many upland soil communities have shown a relatively high C flux through the pentose phosphate (PP) or the Entner-Doudoroff (ED) pathway, thought to be related to oxidative damage control. We tested the hypothesis that the metabolic organization of the central C metabolic network differed between two ecosystems, an anoxic marsh soil and oxic upland soil, and would be affected by altering oxygen concentrations. We expected there to be high PP/ED pathway activity under high oxygen concentrations and in oxic soils and low PP/ED activity in reduced oxygen concentrations and in marsh soil. Although we found high PP/ED activity in the upland soil and low activity in the marsh soil, lowering the oxygen concentration for the upland soil did not reduce the relative PP/ED pathway activity as hypothesized, nor did increasing the oxygen concentration in the marsh soil increase the PP/ED pathway activity. We speculate that the high PP/ED activity in the upland soil, even when exposed to low oxygen concentrations, was related to a high demand for NADPH for biosynthesis, thus reflecting higher microbial growth rates in C-rich soils than in C-poor sediments. Further studies are needed to explain the observed metabolic diversity among soil ecosystems and determine whether it is related to microbial growth rates.IMPORTANCEWe observed that the organization of the central carbon (C) metabolic processes differed between oxic and anoxic soil. However, we also found that the pentose phosphate pathway/Entner-Doudoroff (PP/ED) pathway activity remained high after reducing the oxygen concentration for the upland soil and did not increase in response to an increase in oxygen concentration in the marsh soil. These observations contradicted the hypothesis that oxidative stress is a main driver for high PP/ED activity in soil communities. We suggest that the high PP/ED activity and NADPH production reflect higher anabolic activities and growth rates in the upland soil compared to the anaerobic marsh soil. A greater understanding of the molecular and biochemical processes in soil communities is needed to develop a mechanistic perspective on microbial activities and their relationship to soil C and nutrient cycling. Such an increased mechanistic perspective is ecologically relevant, given that the central carbon metabolic network is intimately tied to the energy metabolism of microbes, the efficiency of new microbial biomass production, and soil organic matter formation.

The Effect of Combined Application of Biocontrol Microorganisms and Arbuscular Mycorrhizal Fungi on Plant Growth and Yield of Tomato (Solanum lycopersicum L.)

Sustainable plant production requires less use of synthetic chemicals in plant nutrition and protection. Microbial products are among the most promising substitutes for chemicals. With the increasing popularity and availability of such products, it has become obligatory to use different microbes together. The effect of this has been tested in several studies, but their results have sometimes been contradictory depending on the microbial strains tested and the mode of application. We tested the effect of two commercially available antagonists and Funneliformis mosseae alone and in combination on tomato. Mycorrhizal treatment increased plant growth and yield, both alone and combined with the antagonists; however, mycorrhizal root colonization was not influenced by the antagonist. This treatment also led to a slight decrease in the occurrence of Trichoderma spp. on tomato roots but did not impede the colonization of roots by the applied Trichoderma strain. Our result confirmed that Trichoderma asperellum (T34) and Streptomyces griseoviridis (K61) can be safely combined with arbuscular mycorrhizal fungi (AMF), namely with F. mosseae.

Gyrotactic bio-magneto-convective combined impacts on magnetorheological hybrid nanoflow: Microbial life on surfaces’ application

Magnetorheological fluid with self-driven ubiquitous motile organisms was affected by various physical factors such as hydrodynamics, dispersion, and distribution of organisms. These fascinating properties attracted us to work on this paper, a Casson hybrid nanoflow model exploring the dynamic behavior of microorganisms along spongy extensible surfaces taking Ohmic heating and chemical reaction into account. Further, the heat transfer phenomena are analyzed in the presence of thermal radiation and space and time-dependent energy sources/sinks. The nanoflow has its base methanol and a mixture of iron and aluminum oxides is suspended. Flow obeying mathematical model is solved numerically using the Runge–Kutta–Fehlberg technique along with the shooting method after imposing self-similarity transformation. Results of various pertinent parameters on the flow characteristic quantities and engineering quantities are portrayed and presented through graphs and tables. Iron oxide methanol nanofluid shows supremacy over hybrid nanoflows as speed is considered, whilst the opposite phenomenon is observed in the case of energy. Hybrid nanoflow makes the surface friction-free. Microorganism concentration difference improvement also helps in the intensification of motile organism growth.

The mechanism of microbial sulfate reduction in high concentration sulfate wastewater enhanced by maifanite

Excessive sulfate levels in water bodies pose a dual threat to the ecological environment and human health. The microbial removal of sulfate encounters challenges, particularly in environments with high sulfate concentrations, where the gradual accumulation of sulfide hampers microbial activity. This study focuses on elucidating the mechanisms underlying the enhancement of microbial sulfate reduction in high-concentration sulfate wastewater through a comparative analysis of maifanite and zeolite biostimulants. The investigation reveals that zeolite primarily facilitates microbial growth by providing attachment sites, while maifanite augments sulfate-reducing bacteria (SRB) activity through the release of active substances such as Mo, Ca, and Cu. The addition of maifanite proves instrumental in enhancing microbial activity, manifesting as increased microbial load and protein production, augmented extracellular polymer generation, accelerated electron transfer, and facilitated microbial growth and biofilm formation. Noteworthy is the observation that the combined application of maifanite and zeolite exhibited a synergistic effect, resulting in a 167 % and 68 % increase in sulfate reduction rate compared to the utilization of maifanite (0.12 d−1) or zeolite (0.19 d−1) in isolation. Within this synergistic context, the relative abundance of Desulfobacteraceae reaches a peak of 15.4 %. The outcomes of this study corroborate the distinct promotion mechanisms of maifanite and zeolite in microbial sulfate reduction, offering novel insights into the application of maifanite in the context of high-concentration sulfate removal.

Key aspects of papillomavirus infection influence the host cervicovaginal microbiome in a preclinical murine papillomavirus (MmuPV1) infection model.

Human papillomaviruses (HPVs) are the most common sexually transmitted infection in the United States and are a major etiological agent of cancers in the anogenital tract and oral cavity. Growing evidence suggests changes in the host microbiome are associated with the natural history and ultimate outcome of HPV infection. We sought to define changes in the host cervicovaginal microbiome during papillomavirus infection, persistence, and pathogenesis using the murine papillomavirus (MmuPV1) cervicovaginal infection model. Cervicovaginal lavages were performed over a time course of MmuPV1 infection in immunocompetent female FVB/N mice and extracted DNA was analyzed by qPCR to track MmuPV1 viral copy number. 16S ribosomal RNA (rRNA) gene sequencing was used to determine the composition and diversity of microbial communities throughout this time course. We also sought to determine whether specific microbial communities exist across the spectrum of MmuPV1-induced neoplastic disease. We, therefore, performed laser-capture microdissection to isolate regions of disease representing all stages of neoplastic disease progression (normal, low- and high-grade dysplasia, and cancer) from female reproductive tract tissue sections from MmuPV1-infected mice and performed 16S rRNA sequencing. Consistent with other studies, we found that the natural murine cervicovaginal microbiome is highly variable across different experiments. Despite these differences in initial microbiome composition between experiments, we observed that MmuPV1 persistence, viral load, and severity of disease influenced the composition of the cervicovaginal microbiome. These studies demonstrate that papillomavirus infection can alter the cervicovaginal microbiome.IMPORTANCEHuman papillomaviruses (HPVs) are the most common sexually transmitted infection in the United States. A subset of HPVs that infect the anogenital tract (cervix, vagina, anus) and oral cavity cause at least 5% of cancers worldwide. Recent evidence indicates that the community of microbial organisms present in the human cervix and vagina, known as the cervicovaginal microbiome, plays a role in HPV-induced cervical cancer. However, the mechanisms underlying this interplay are not well-defined. In this study, we infected the female reproductive tract of mice with a murine papillomavirus (MmuPV1) and found that key aspects of papillomavirus infection and disease influence the host cervicovaginal microbiome. This is the first study to define changes in the host microbiome associated with MmuPV1 infection in a preclinical animal model of HPV-induced cervical cancer. These results pave the way for using MmuPV1 infection models to further investigate the interactions between papillomaviruses and the host microbiome.

Rapid biotransformation of STW 5 constituents by human gut microbiome from IBS- and non-IBS donors.

STW 5 is an herbal medicinal product with proven clinical efficacy in the treatment of functional gastrointestinal disorders, like functional dyspepsia and irritable bowel syndrome (IBS). The effects of STW 5 on fecal microbial communities and metabolite production effects have been studied in an experimental model with fecal samples from individuals with and without IBS. While only minor taxonomic disparities were noted between IBS- and non-IBS samples and upon treatment with STW 5, rapid metabolic turnover of STW 5 components into specific degradation products with reported anti-inflammatory, cytoprotective, or spasmolytic activities was observed, which may be relevant for the pharmacological activity of STW 5.

Prairie restoration promotes the abundance and diversity of mutualistic arbuscular mycorrhizal fungi.

Predicting how biological communities assemble in restored ecosystems can assist in conservation efforts, but most research has focused on plants, with relatively little attention paid to soil microbial organisms that plants interact with. Arbuscular mycorrhizal (AM) fungi are an ecologically significant functional group of soil microbes that form mutualistic symbioses with plants and could therefore respond positively to plant community restoration. To evaluate the effects of plant community restoration on AM fungi, we compared AM fungal abundance, species richness, and community composition of five annually cultivated, conventionally managed agricultural fields with paired adjacent retired agricultural fields that had undergone prairie restoration 5-9 years prior to sampling. We hypothesized that restoration stimulates AM fungal abundance and species richness, particularly for disturbance-sensitive taxa, and that gains of new taxa would not displace AM fungal species present prior to restoration due to legacy effects. AM fungal abundance was quantified by measuring soil spore density and root colonization. AM fungal species richness and community composition were determined in soils and plant roots using DNA high-throughput sequencing. Soil spore density was 2.3 times higher in restored prairies compared to agricultural fields, but AM fungal root colonization did not differ between land use types. AM fungal species richness was 2.7 and 1.4 times higher in restored prairies versus agricultural fields for soil and roots, respectively. The abundance of Glomeraceae, a disturbance-tolerant family, decreased by 25% from agricultural to restored prairie soils but did not differ in plant roots. The abundance of Claroideoglomeraceae and Diversisporaceae, both disturbance-sensitive families, was 4.6 and 3.2 times higher in restored prairie versus agricultural soils, respectively. Species turnover was higher than expected relative to a null model, indicating that AM fungal species were gained by replacement. Our findings demonstrate that restoration can promote a relatively rapid increase in the abundance and diversity of soil microbial communities that had been degraded by decades of intensive land use, and community compositional change can be predicted by the disturbance tolerance of soil microbial taxonomic and functional groups.

Soil contribution to the cobalamin (vitamin B12) supply of terrestrial organisms

AbstractCobalamin (Vitamin B12) is a cofactor for many enzymes, including those in bacteria, archaea, algae, and mammals. In humans, cobalamin deficiency can lead to pernicious anaemia as well as gastrointestinal and neurological disorders. In contrast to marine ecosystems, there is a great paucity of information on the role of soils and terrestrial plants in the supply of cobalt and cobalamin to microorganisms and animals. The content of cobalt cations in most soils is usually sufficient to maintain growth, and the density of cobalamin-producing soil prokaryotes is high in comparison to water bodies. The cobalt content of most soils is usually sufficient in comparison with water, and the density of cobalamin-producing soil prokaryotes is high. Therefore, terrestrial plants are an important cobalt source for cobalamin-producing rumen and gut prokaryotes. The major source of cobalamin for most other animals is the meat of ruminants as well as other animal-derived products, bacteria in insects, and coprophagy, e.g., by rodents. In addition, faecal deposits, and fertilizers as well as soil bacteria add to the cobalamin supply. However, those archaea and bacteria that do not produce cobalamin obtain this coenzyme or its analogues from the environment. Therefore, presence or absence of cobalamin-producing species in soil affects the whole soil microbiome. However, our knowledge concerning microbial producers and consumers of cobalamin in soils is still limited, despite some recent advances. The main reasons are a low cobalamin content in soils and challenging methods of determination. In this regard, advanced analytical knowledge and technical equipment are required, which are usually unavailable in soil laboratories. This review provides relevant methodological information on sample homogenization, extraction, concentration, and purification as well as analysis of cobalamin.

Polyglutamate: Unleashing the Versatility of a Biopolymer for Cosmetic Industry Applications

Polyglutamic acid (PGA), a biopolymer comprising repeating units of glutamic acid, has garnered significant attention owing to its versatile applications. In recent years, microbial production processes have emerged as promising methods for the large-scale synthesis of PGA, offering advantages such as sustainability, efficiency, and tailored molecular properties. Beyond its industrial applications, PGA exhibits unique properties that render it an attractive candidate for use in the cosmetic industry. The biocompatibility, water solubility, and film-forming characteristics of PGA make it an ideal ingredient for cosmetic formulations. This article explores the extensive potential cosmetic applications of PGA, highlighting its multifaceted role in skincare, haircare, and various beauty products. From moisturizing formulations to depigmentating agents and sunscreen products, PGA offers a wide array of benefits. Its ability to deeply hydrate the skin and hair makes it an ideal ingredient for moisturizers, conditioners, and hydrating masks. Moreover, PGA’s depigmentating properties contribute to the reduction in hyperpigmentation and uneven skin tone, enhancing the overall complexion. As the demand for sustainable and bio-derived cosmetic ingredients escalates, comprehending the microbial production and cosmetic benefits of PGA becomes crucial for driving innovation in the cosmetic sector.

Microbial and insect oils: A sustainable approach to functional lipid

AbstractThe increasing global population, coupled with the effects of climate change on agricultural activities has spurred a demand for sustainable food production to meet human needs. In response to this, there has been a growing interest in sustainable food production initiatives. One of such initiatives is harnessing microbial and insect lipids as valuable ingredients to address increase in demand for lipids across various sectors, including functional food, nutritional supplements, and biodiesel production. Over the last decades, there has been increasing scientific investigations exploring lipid from algae, microbes, and insects as alternatives to traditional agro‐ and marine‐based sources. This review, therefore, presents progress made in microbial and insect oils production, with emphasis on sustainability. Emerging extraction techniques, regulatory and safety requirements, and challenges that exist in the production and utilization of these new lipids are also discussed. The review shows that lipids from a wide range of oleaginous microorganisms and insect species have the potential to serve as a valuable ingredient for healthful food preparation. However, challenges such as cultural acceptance, lack of standardized regulations, high cost, and low yield associated with most emerging environmentally friendly extraction technologies continue to hinder widespread use or adoption of microbial and insect lipids on a global scale. These challenges call for innovations to reduce cost of production and improve lipids yield. So far, a substantial progress has been made in the utilization of readily available feedstocks such as industrial food wastes and sugar‐rich industrial wastewater to grow insects and microorganisms which will significantly reduce the processing costs.

Root mucilage nitrogen for rhizosphere microorganisms under drought

AbstractNitrogen (N) is a crucial nutrient for the growth and activity of rhizosphere microorganisms, particularly during drought conditions. Plant root-secreted mucilage contains N that could potentially nourish rhizosphere microbial communities. However, there remains a significant gap in understanding mucilage N content, its source, and its utilization by microorganisms under drought stress. In this study, we investigated the impact of four maize varieties (DH02 and DH04 from Kenya, and Kentos and Keops from Germany) on the secretion rates of mucilage from aerial roots and explored the origin of mucilage N supporting microbial life in the rhizosphere. We found that DH02 exhibited a 96% higher mucilage secretion rate compared to Kentos, while Keops showed 114% and 89% higher secretion rates compared to Kentos and DH04, respectively. On average, the four maize varieties released 4 μg N per root tip per day, representing 2% of total mucilage secretion. Notably, the natural abundance of 15N isotopes increased (higher δ15N signature) with mucilage N release. This indicates a potential dilution of the isotopic signal from biological fixation of atmospheric N by mucilage-inhabiting bacteria as mucilage secretion rates increase. We proposed a model linking mucilage secretion to a mixture of isotopic signatures and estimated that biological N fixation may contribute to 45 - 75% of mucilage N per root tip. The N content of mucilage from a single maize root tip can support a bacterial population ranging from 107 to 1010 cells per day. In conclusion, mucilage serves as a significant N-rich resource for microbial communities in the rhizosphere during drought conditions.

Extremophiles and their expanding biotechnological applications.

Microbial life is not restricted to any particular setting. Over the past several decades, it has been evident that microbial populations can exist in a wide range of environments, including those with extremes in temperature, pressure, salinity, and pH. Bacteria and Archaea are the two most reported types of microbes that can sustain in extreme environments, such as hot springs, ice caves, acid drainage, and salt marshes. Some can even grow in toxic waste, organic solvents, and heavy metals. These microbes are called extremophiles. There exist certain microorganisms that are found capable of thriving in two or more extreme physiological conditions simultaneously, and are regarded as polyextremophiles. Extremophiles possess several physiological and molecular adaptations including production of extremolytes, ice nucleating proteins, pigments, extremozymes and exopolysaccharides. These metabolites are used in many biotechnological industries for making biofuels, developing new medicines, food additives, cryoprotective agents etc. Further, the study of extremophiles holds great significance in astrobiology. The current review summarizes the diversity of microorganisms inhabiting challenging environments and the biotechnological and therapeutic applications of the active metabolites obtained as a response to stress conditions. Bioprospection of extremophiles provides a progressive direction with significant enhancement in economy. Moreover, the introduction to omics approach including whole genome sequencing, single cell genomics, proteomics, metagenomics etc., has made it possible to find many unique microbial communities that could be otherwise difficult to cultivate using traditional methods. These findings might be capable enough to state that discovery of extremophiles can bring evolution to biotechnology.

Genes in the Chagra: Crop and Crop Wild Relative Landesque Capital among Amazonian Runa in Ecuador

This study delves into the relationship between human cultures and plant genetic diversity, centering on the expanded concept of landesque capital. Traditionally, this term has encapsulated human-made environmental modifications, such as anthropogenic soils or terraces, that can yield long-term benefits. We extend this notion to embrace the genetic diversity and dynamics of crops and crop wild relative (CWR) gene pools. The investigation focuses on the Napo Runa of Ecuador and their cultural practices, including selection, seed saving, and transplantation, to highlight potential models of selection pressures affecting crop-CWR complexes and any cultural practices connected to either. In doing so, we aim to underscore the interconnected and multispecies nature of the relationships among genetic diversity and cultural diversity. Changes in the genetic makeup of one plant, induced by human interaction, can affect its cultivated counterparts through hybridization or future breeding programs, thereby influencing agricultural resilience, nutritional value, and the very cultural practices dependent on these crops or any related to them. Consequently, we argue for a focused examination of plant-based forms of landesque capital or any gene pool-based form, including animals or microbial life. This approach highlights the importance of interconnecting biocultural diversity between cultivated plants and their “wild” relatives and recognizing the intricate interdependencies between cultural practices and gene pools in the face of environmental challenges.

Microalgae cultivation trials in a membrane bioreactor operated in heterotrophic, mixotrophic, and phototrophic modes using ammonium-rich wastewater: The study of fouling

ABSTRACT In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem.

Diversity of culturable gut bacteria in natural aphid populations and their contribution to insecticide degradation

Microorganisms in insects play pivotal roles in various aspects, including nutrition, development, protection, physiology, and behavior. Aphids, a distinct group of insects that feed on plant sap, have been the focus of research exploring the intricate relationships between microbes and insects. While extensive investigations have delved into the obligate endosymbionts in aphids, there remains a gap in understanding the diversity of gut microbes and other associated microorganisms. This study employed culture-dependent methods to isolate microorganisms from diverse aphid species (Aphis gossypii, A. nerii, A. craccivora, Hysteroneura setariae, and Myzus persicae). The results identified three bacterial phyla (Firmicutes, Proteobacteria, Actinobacteria), belonging to families such as Bacillaceae, Corynebacteriaceae, Micrococcaceae, Morganellaceae, Staphylococcaceae, and Xanthomonadaceae. Bacillus emerged as the predominant taxon, with Aphis craccivora exhibiting both high abundance and an even distribution of bacteria. Both A. craccivora and A. gossypii displayed a diverse array of bacterial species, with A. gossypii exhibiting the highest dominance index. Hysteroneura setariae showcased a diverse dominance of bacteria among aphids. Notably, the microorganisms Exiguobacterium indicum MPB-2 and Pseudomonas hibiscicola CCF 2-2 demonstrated the ability to degrade imidacloprid at a rate of 18–22%. This finding emphasizes their capacity to utilize insecticides as sole sources of carbon and nitrogen, ultimately benefiting the fitness of the insects. This study contributes to our understanding of the microorganisms presented in aphids. Highlighting the efficacy of culture-dependent methods in unveiling the diversity of these microscopic organisms.

Single-cell analysis reveals an active and heterotrophic microbiome in the Guaymas Basin deep subsurface with significant inorganic carbon fixation by heterotrophs.

The global subsurface is the largest reservoir of microbial life on the planet yet remains poorly characterized. The activity of life in this realm has implications for long-term elemental cycling, particularly of carbon, as well as how life survives in extreme environments. Here, we recovered cells from the deep subsurface of the Guaymas Basin and investigated the level and distribution of microbial activity, the physicochemical drivers of activity, and the relative significance of organic versus inorganic carbon to subsurface biomass. Using a sensitive single-cell assay, we found that the majority of cells are active, that activity is likely driven by the availability of energy, and that although heterotrophy is the dominant metabolism, both organic and inorganic carbon are used to generate biomass. Using a new approach, we quantified inorganic carbon assimilation by heterotrophs and highlighted the importance of this often-overlooked mode of carbon assimilation in the subsurface and beyond.

Past, present and future of glycolipids from Ustilaginaceae – A review on cellobiose lipids and mannosylerythritol lipids

AbstractThe glycolipids cellobiose lipids (CL) and mannosylerythritol lipids (MEL) are biosurfactants mainly synthesized by microorganisms of the Ustilaginaceae family. They have a large structural diversity, varying in their sugar moieties and the attached fatty acids, resulting in a prospectively broad range of applications. This literature review provides a detailed overview of known microbial producers of CL and MEL, and their respective metabolic pathways that result in different molecular structures. Further, current advances in the aerobic fermentative synthesis of the glycolipids and their purification methods are illustrated. All influencing factors identified to date with regard to the fermentation are highlighted in detail: For CL synthesis usually hydrophilic carbon sources are used as substrate, whereas hydrophobic carbon sources are usually metabolized to MEL. Nitrogen limitation was described as a major trigger for glycolipid synthesis and an acidic pH range was favored for increased CL production. An overview of applied fermentation parameters in recent publications (e.g., substrate‐concentrations, feeding approaches) demonstrates the future potential of CL and MEL production optimization. Foaming during fermentation is either combated or exploited by foam fractionation as the first purification step. The current purification processes focus on solvent extractions and chromatography in the laboratory scale and a need for development was identified for future scale‐up. Finally, environmental hotspots during CL and MEL production are presented and future optimization potentials are highlighted.

150 Development of a leaky gut model: Meta-analysis of plasma and fecal markers of leaky gut

Abstract Intestinal integrity can be compromised in livestock and poultry species during stress events, including off-feed events. To develop a leaky gut model, weanling barrows 26 to 28 d old [n = 307; Duroc terminal line Fast genetics, initial body weight (BW) = 5.90 ± 0.47 kg), were used in a total of 6 randomized complete block experiments at the NutriQuest modeling center (Fergus Falls, MN). All trials included positive control (PC) and negative control (NC) treatments. The other treatments evaluated (n = 8) were various strains and levels of direct-fed microbial (DFM) products. With the exception of PC, all treatments had complete 24-h feed restriction (FR) approximately 18 d after arrival. Pigs assigned to PC had ad libitum access to feed. Pigs were housed 3 pigs per pen in 1 of 30 pens, and all pigs were fed a common high-quality basal diet. For 3 trials, pigs received Excede (Zoetis; Parsipanny, NJ) IM upon arrival and were provided gentamycin via water for 3 d post-arrival. For 3 trials, no prophylactic antibiotics were administered. Eighteen days post-arrival, fecal and plasma samples were collected from all pigs and feed was removed from FR pens. After 24 h, plasma and fecal samples were collected from all pigs, and one-half of the pigs per trial were harvested for tissue collection. Four days after FR, samples were collected similarly, and the remaining pigs were harvested. Plasma samples were analyzed for LPS binding protein concentrations (LBP), and fecal samples were analyzed for myeloperoxidase (MPO) concentrations. Data from the PC (n = 90) and NC (n = 92) treatments only were analyzed as Individual Participant Data meta-analysis using PROC MIXED of SAS. Data from all pigs (n = 307) were analyzed using PROC REG of SAS with forward step-wise selection to determine relationships between response variables. Plasma LBP concentrations did not differ between PC and NC 24 h after FR (P = 0.14). However, change in LBP concentrations and the ratio of LBP immediately before and after FR, differed between PC and NC (P &amp;lt; 0.001). For NC, LBP concentrations decreased, and for PC, LBP concentrations increased (Table 1). There was no effect of treatment on fecal MPO concentrations. Using the broader dataset (n = 307), variables that were predictive of plasma LBP concentrations immediately following FR were trial (P &amp;lt; 0.001), treatment (P &amp;lt; 0.001), and fecal MPO concentrations (P &amp;lt; 0.05). Variables that were predictive of change in LBP concentrations before and after FR were trial (P &amp;lt; 0.001), treatment (P &amp;lt; 0.001), and initial BW (P &amp;lt; 0.01). These data, taken with data presented in a companion abstract on ileal tight junction gene expression, suggest that plasma LBP concentrations immediately following a FR event are a useful marker of leaky gut. Fecal MPO concentrations do not consistently respond to FR.

Microbial production of 3-hydroxypropionic acid by acetic acid bacteria: Modeling including the buffering capacity of the biological medium enables prediction of pH and metabolite concentrations

A mathematical model of the fed-batch bioconversion of 1,3-propanediol into 3-hydroxypropionic acid using acetic acid bacteria is proposed. The model includes the microbial growth, the oxidation of 1,3-propanediol to 3-hydroxypropionaldehyde followed by a second oxidation reaction to 3-hydroxypropionic acid. The inhibitory effect of the total acid concentration upon the biological reactions was considered as well as the effect of pH on bacterial growth. A special attention was paid to make accurate pH predictions as pH is a key parameter that influences the microbial growth and bioconversion and also defines the strategy of downstream processing for acid recovery. The buffering capacity of the complex biological medium was found to change throughout the bioconversion. In addition to describing satisfactorily a set of experiments reported in the literature, the model was successfully used to predict metabolite concentrations and the resulting pH in new operating conditions with free pH dynamics. A sensitivity analysis was performed to identify the most influential parameters of the model. The proposed model represents a valuable tool for bioprocess design as it describes the detailed kinetics of 1,3-propanediol oxidation to 3-hydroxypropionic acid by acetic acid bacteria in bioreactor. Additionally, the pH prediction is a major feature of this model, which could guide the identification of optimal operating conditions for microbial activity with a simultaneous in-situ recovery process.