The Role of Segmented Filamentous Bacteria in Immune Barrier Maturation of the Small Intestine at Weaning

The microbiological, physical, chemical, and immunological barriers of the gastrointestinal tract (GIT) begin developing in utero and finish maturing postnatally. Maturation of these barriers is essential for the proper functioning of the GIT. Maturation, particularly of the immunological barrier, involves stimulation by bacteria. Segmented filamentous bacteria (SFB) which are anaerobic, spore-forming commensals have been linked to immune activation. The presence and changes in SFB abundance have been positively correlated to immune markers (cytokines and immunoglobulins) in the rat ileum and stool samples, pre- and post-weaning. The abundance of SFB in infant stool increases from 6 months, peaks around 12 months and plateaus 25 months post-weaning. Changes in SFB abundance at these times correlate positively and negatively with the production of interleukin 17 (IL 17) and immunoglobulin A (IgA), respectively, indicating involvement in immune function and maturation. Additionally, the peak in SFB abundance when a human milk diet was complemented by solid foods hints at a diet effect. SFB genome analysis revealed enzymes involved in metabolic pathways for survival, growth and development, host mucosal attachment and substrate acquisition. This narrative review discusses the current knowledge of SFB and their suggested effects on the small intestine immune system. Referencing the published genomes of rat and mouse SFB, the use of food substrates to modulate SFB abundance is proposed while considering their effects on other microbes. Changes in the immune response caused by the interaction of food substrate with SFB may provide insight into their role in infant immunological barrier maturation.

A hymenopteran odorant alerts flies to bury eggs

Ants are ubiquitous and consume insects at all life stages, presumably creating a strong selective pressure for ant avoidance behaviors across insects. The insect egg stage can be especially defenseless against predation given that eggs are usually immobile and unguarded, suggesting insect mothers may have evolved oviposition strategies to minimize the ant predation risk to their offspring. Given the lack of parental care in most insects, these oviposition strategies would likely be innate rather than learned, since insect mothers are not usually present to assess predation of their eggs. Here, we use the vinegar fly Drosophila melanogaster as a model system for examining parental defensive responses to ant presence. Flies usually lay eggs partially inserted into the food substrate, although some are laid on top of the food and a few are inserted deeply into the food. We found that exposure to ants significantly alters fly oviposition depth: the proportion of eggs on the food surface decreased while the proportion of buried eggs increased. Buried eggs survive ant foraging bouts better than surface eggs, showing that this oviposition depth behavior is adaptive. This induced behavior is conserved across the genus Drosophila and is dependent on the fly olfactory system: anosmic mutant flies fail to bury their eggs in the presence of ants, and ant odor extracts are sufficient to induce egg burying. By fractionating ant body washes and using GC-MS to identify fraction constituents, we identified the saturated, long-chain alcohol 1-octadecanol as the odorant flies use to sense ant presence. To further delineate the ant lineages to which flies respond, we exposed flies to the odors from numerous species of ants and other insects. Surprisingly, flies buried their eggs in response to the odors of nearly all hymenopterans tested, including hymenopteran groups that flies rarely interact with in nature like bees and paper wasps. Our data suggest that 1-octadecanol is a conserved and ancient hymenopteran odorant, and that drosophilids evolved a mechanism for sensing this odorant early in their evolution as a means of protecting their offspring from ant predation. This study sheds light on the ecology and mechanisms underlying a common biotic interaction in nature, that between insect parents and the ants that would consume their offspring.

Geometric Morphometrics Captures Variations in Wing Development of Black Soldier Flies

The black soldier fly is considered an important insect due to its ability to convert organic wast into high quality organic fertilizer. Studies have shown that food quality at the larvae stage contributes greatly to their development. In this study, we applied geometric morphometric measurements to access the variations in the black soldier fly fed on different food substrates as captured in the wings. Eggs of black soldier fly were collected from the field and cultured on different food substrates such as; restaurant waste, fruit waste, wheat brand and layer meal until maturity. The right fore wing of 140 individuals of black were used for the experiment. The results showed a significant difference between the shape of landmarks within each food substrate group. Landmark 3, 7 and 9, corresponding to end of first radial vein R1, intersession between medio-cubital vein and cubito-anal vein (m-cu and CuA), and intersission between cubito Anal vein and Anal vein (CuA + Cup) contributed most to the variation between the different food substrates. Partial least square showed a strong association between food substrate and wing development. Therefore, the variations in wing development could be due to the impact of nutritional compositions quality of the different food substrates.

Evaluating crude whey for bioethanol production using non-Saccharomyces yeast, Kluyveromyces marxianus

Ethanol production from non-food substrate is strongly recommended to avoid competition with food production. Whey, which is rich in nutrients, is one of the non-food substrate for ethanol production by Kluyveromyces spp. The purpose of this study was to optimize ethanol from different crude (non-deproteinized, non-pH adjusted, and non-diluted) whey using K. marxianus ETP87 which was isolated from traditional yoghurt. The sterilized and non-sterilized whey were employed for K. marxianus ETP87 substrate to evaluate the yeast competition potential with lactic acid and other microflora in whey. The effect of pH and temperature on ethanol productivity from whey was also investigated. Peptone, yeast extract, ammonium sulfate ((NH4)2SO4), and urea were supplemented to whey in order to investigate the requirement of additional nutrient for ethanol optimization. The ethanol obtained from non-sterilized whey was slightly and statistically lower than sterilized whey. The whey storage at 4 °C didn’t guarantee the constant lactose presence at longer preservation time. Significantly high amount of ethanol was attained from whey without pH adjustment (3.9) even if it was lower than pH controlled (5.0) whey. The thermophilic yeast, K. marxianus ETP87, yielded high ethanol between 30 and 35 °C, and the yeast was able to produce high ethanol until 45 °C, and significantly lower ethanol was recorded at 50 °C. The ammonium sulfate and peptone enhanced ethanol productivity, whereas yeast extract and urea depressed the yeast ethanol fermentation capability. The K. marxianus ETP87, the yeast isolated from traditional yoghurt, is capable of producing ethanol from non-sterilized and non-deproteinized substrates.

ComBase models are valid for predicting fate of Listeria monocytogenes on ten whole intact raw fruits and vegetables

L. monocytogenes was associated with more than 60 produce recalls between 2017 and 2020 including tomato, cherry, broccoli, lemon, and lime recalls. This study describes the effects of temperature, time and food substrate as factors influencing L. monocytogenes behavior on whole intact raw fruits and vegetables. A cocktail of five L. monocytogenes strains previously associated with foodborne outbreaks were used. Ten intact whole fruit and vegetable commodities were chosen based on data gaps identified in a systematic literature review. Produce investigated belong to major commodity families: Ericaceae (blackberry, raspberry, and blueberry), Rutaceae (lemon and mandarin orange), Roseaceae (sweet cherry), Solanaceae (tomato), Brassaceae (cauliflower and broccoli) and Apiaceae (carrot). Intact inoculated whole fruit and vegetable commodities were incubated at 2, 12, 22, 30 and 35 °C with relative humidities matched to typical real-world conditions. Foods were sampled (n=6) for up to 28 days, depending on temperature. Growth and decline rates were estimated using the DMFit for Excel. Growth rates were compared with ComBase modeling predictions for L. monocytogenes. Almost every experiment showed initial growth, followed by subsequent decline. L. monocytogenes was able to grow on whole intact surface of all produce tested, except for carrot. The 10 produce commodities supported growth of L. monocytogenes at 22 and 35°C. Growth and survival at 2 and 12°C varied by produce commodity. The standard deviation of the square root growth and decline rates showed significantly larger variability in both growth and decline rates within replicates as temperature increased. When L. monocytogenes growth occurred, it was conservatively modeled by ComBase Predictor, and growth was generally followed by decreases in concentration. This research will assist in understanding the risks of foodborne disease outbreaks and recalls associated with L. monocytogenes on fresh whole produce.

A Cell-Based Biosensor System for Listeria monocytogenes Detection in Food

Listeria monocytogenes is an intracellular bacterium that causes serious epidemic and sporadic food-borne illnesses in humans. Rapid and trustworthy methods are necessary for the detection of the pathogen to prevent potential food contamination. The aim of this study was to test a newly developed L. monocytogenes biosensor on actual food samples and validate its ability to detect the presence of pathogens robustly and accurately. The newly developed method uses a cell-based biosensor technology (BERA) and a portable device developed by EMBIO Diagnostics called B.EL.D, and provides results within 3 min. Tests were conducted on ready-to-eat lettuce salads, milk and halloumi cheese and the results indicate that the novel system was able to identify inoculated samples with 98%, 90%, and 91% accuracy, respectively. Furthermore, the limit of detection was determined to be as low as 0.6 log CFU mL−1 or g−1 in all food types. Classification of the samples Above or Below the detection limit was accessed through a newly developed algorithm for each food substrate. Samples were also analyzed with the ISO 11290-1:2017 and 11290-2:2017, in parallel. Thus, it was concluded that the newly developed biosensor can be a useful tool in the food supply chain, decreasing the required time for the detection of pathogens and increasing the number of tested samples before they reach the market.

Gut bacteria mediate nutrient availability in Drosophila diets

SummaryDrosophila melanogaster gut microbes play important roles in host nutritional physiology. However, these associations are often indirect and studies typically are in the context of specialized nutritional conditions, making it difficult to discern how microbiome-mediated impacts translate to physiologically relevant conditions, in the laboratory or nature. Here, we show that on three artificial diets and a natural diet of grapes, D. melanogaster gut bacteria alter protein, carbohydrates, and moisture of the food substrate. In depth analysis on one diet revealed bacteria also increase tryptophan levels. We investigate how nutrient changes impact life history and find that, while alterations to dietary protein and carbohydrates are arguably the most significant consequence of bacterial association, other factors, such as micronutrients, likely contribute to life history traits in a diet-dependent manner. Our work demonstrates that while some bacterial impacts on nutrition occur across experimental diets, others are dictated by unique dietary environments.

Assessment of earthworms activity based on eaten biomass from selected catch crops

The trophic activity of soil mesofauna, especially earthworms (the Lumbricidae family), is a key element in increasing the fertility of agroecosystems. Thee food strategies that earthworms use as part of the trophic networks in soil, and especially their food preferences, are still unknown. Much is known about what is the food substrate of earthworms, but the food preferences of individual species, as well as the possibilities and dynamics of food processing are not fully understood. The aim of the experiment was to observe the amount and dynamics of food uptake by the earthworms of the species Lumbricus terrestris L., which is a common species of soil Oligochaeta in agricultural areas, as well as to propose a new decomposition rate measuring the strength of the earthworm population and its contribution to the mechanism of processing plant organic matter.