Sole Food Source Research Articles

Orange peel extract enhanced sugar recovery and butanol production from potato peel by Clostridium acetobutylicum

ABSTRACT The present study is focused on biobutanol production from potato peel waste in dilute orange peel extract by Clostridium acetobutylicum MTCC 11274 at three concentrations of 20, 40, and 60 g/L as sole nutrient sources. The biomass and solvent production from potato peel were enhanced in orange peel extract with the concentration and improved the sugar recovery. The effect on solvent production from 60 g/L potato peel in dilute orange peel extract was relatively higher than 20 and 40 g/L. The butanol yield was improved from 0.04 to 0.35 g/g from 60 g/L potato peel waste in orange peel extract. The butyric acid concentration was highly correlated with butanol production. The Clostridium acetobutylicum MTCC 11274 showed no inhibitory effect from D-limonene in orange peel extract. The potato peel waste hydrolyzate prepared in orange peel extract enhanced the growth of Clostridium acetobutylicum MTCC 11274 and fermentation of acetone, butanol, and ethanol.

Histological changes induced by the cynipid wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae) in leaves of the chestnut Castanea sativa (Fagaceae): Mechanisms of galling impact on host vigor

Dryocosmus kuriphilus (Hymenoptera: Cynipidae), the Asian chestnut gall wasp (ACGW), is an invasive pest that threatens native stands and orchards of European Sweet Chestnut (Castanea sativa Mill.). ACGW induces galls in stems, petioles, and midribs. These galls cause inhibition of tree growth and fruit production. An understanding of morphogenetic changes in host organs is important to evaluate how plant resources are redirected to galls. Structural divergences in C. sativa petioles, midribs, and respective galls were investigated. Larvae of D. kuriphilus are found in the central region of young petioles and midribs in the spring. They are positioned in the pith region of petioles and midribs, surrounded by vascular tissues. The increase in cell layers and volume is evident in the ground tissues of galls, i.e., parenchyma, collenchyma, and sclerenchyma that originate from ground meristem. Gall formation causes the separation of the original vascular system into several collateral and amphicribral vascular bundles. The vascular web branching likely favors the redirection of resources from developing leaf blades to the galls by compensatory hydraulic mechanisms. The rapid growth rates of galls are likely supported by an increased water supply to gall sites. Cytoplasmically dense and metabolically active nutritive linings of the larval chambers are the sole source of food for larvae. Nutritive cells are maintained by a rich vascular supply. The redifferentiation of mechanical tissue surrounding the nutritive tissue also requires energy and protects the D. kuriphilus larva until pupation. These vascular alterations impact the normal formation of tissues in distal regions of the leaf, which reduces the productivity of chestnut trees.

Microflora communities which can convert digested sludge to biogas

ABSTRACT In the present study, we developed several microflora communities that utilize digested sludge (DS), the recalcitrant waste product of anaerobic digestion, as a substrate for biogas production with the aim of their future application to DS recycling. Strict enrichment with DS as the sole nutrient source was introduced to culture microbes from soil and herbivore dung samples; microflora communities promoting stable levels of biogas production were obtained. The average methane and hydrogen yield from soil-derived microflora were 4.86 and 0.94 ml per 1.0 g DS, respectively. Notably, two microflora communities enriched from a riverbank sediment produced 20.79 ml and 14.10 ml methane from 1.0 g DS. By contrast, the methane and hydrogen yield for herbivore dung-derived microfloras were on average 1.31 ml and 1.87 ml per 1.0 g DS, respectively. Potent hydrogen-biogas producers were obtained from rabbit (4.12 ml per 1.0 g DS), goat (3.16 ml per 1.0 g DS), and sheep dung (2.52 ml per 1.0 g DS). The cultured microflora communities included representatives from the eubacterial genera, Clostridiaceae and Eubacteriaceae together with several anaerobic genera. Pseudomonas spp. are found in the riverbank sediment-derived microfloras, suggesting that the floras employ syntrophic acetate oxidation and hydrogentrophic methanogenesis (SAO-HM) pathway for methane production. The methanogenic microflora communities were dominated by bacteria from the Methanobacteriaceae family and unclassified archaea. Moreover, ascomycetous fungi and protists were found, implying that they act as oxygen scavengers and bacterial grazers, respectively. Enzymatic analysis suggested that the microfloras hydrolyze DS via cellulase, chitinase, and protease activities.

Bee pollen as a novel substrate in pilot-scale probiotic-mediated lactic fermentation processes

Different process conditions were evaluated to induce lactic acid fermentation of bee pollen at the pilot scale using three different commercial starter cultures. Clean and dry Colombian high Andean bee pollen was used as the sole source of nutrients (substrate). The effect of substrate preparation conditions (water:pollen ratio and initial substrate acidity) on lactic fermentation was evaluated by monitoring pH, titratable acidity, and pollen morphology in 6-kg-fermentation units. A 2:1 water:pollen mixture with an initial pH adjusted to 5.8, pretreated with heat/pressure (10 min; 80 kPa; 115 °C), was determined to be an adequate substrate for pilot-scale lactic fermentation for all lactic starter cultures. At the selected conditions, the kinetics of lactic acid production and the growth of specific lactic bacteria were determined. The fermentation process time was 30 h, after which a significant decline in bacterial populations was observed. Among the starter cultures tested, one constituted exclusively by probiotic Lactobacillus acidophilus NCFM presented the best performance in terms of lactic acid production, with a concentration of 1.65% wt, after 30 h. The results highlight the feasibility of producing fermented bee pollen at a commercial scale as a functional food product with probiotic features.

Partially treated domestic wastewater as a nutrient source for tomatoes (Lycopersicum solanum) grown in a hydroponic system: effect on nutrient absorption and yield

Using effluent from the anaerobic baffled reactor (ABR) of the decentralised wastewater treatment system (DEWATS) as a sole nutrient source is not sufficient for tomato plants grown in hydroponic system. The study investigated the effects of commercial hydroponic fertilizer mix (CHFM) combined with ABR effluent on tomato growth and yield. A media-based hydroponic technique consisting of three treatments, namely, ABR effluent, CHFM, and ABR effluent combined with CHFM (ABR + CHFM (50:50 v/v) was used. The results showed that plant growth parameters, biomass, fruit yield and shoot nutrient content were significantly higher in tomato plants fed with CHFM and ABR + CHFM than those grown in ABR effluent. Addition of 50 % dose of CHFM in ABR wastewater (ABR + CHFM) increased shoot N, K, Ca and Zn. These results indicated that adding 50% CHFM can alleviate nutrient deficiencies when partially treated wastewater from anaerobic digester is used as a nutrient source for hydroponic tomato cultivation.

Protein fraction, mineral profile, and chemical compositions of various fiber-based substrates degraded by Pleurotus ostreatus

The objective of this study was to characterize the substrates after their degradation by P. ostreatus within 60 days of cultivation in four Mexican mushroom-producing companies, in order to use it as a complement feed for ruminants. The acid detergent fiber (ADF), neutral detergent fiber (NDF), protein fraction, and mineral profile were analyzed after degradation. Crude protein (CP) of companies 1 and 4 increased by 6.1% and 6.8%, respectively (p ≤ 0.05). Soluble nitrogen reached 60% relative to un-degraded substrate with 43.8%. Proteins A, B1, and B3 fractions increased compared to controls (p ≤ 0.05) at some companies. The B2 fraction was decreased in all the degraded substrates (p ≤ 0.05), but the C fraction at companies 1, 2, and 3 presented no significant differences with respect to their controls (p ≤ 0.05). Crude fiber (CF), ADF, NDF, and hemicellulose (HC) decreased while dry matter digestibility (DMD) increased to 55.5-58% on degrade substrates. The mineral composition increased disproportionately. The substrate degraded by P. ostreatus by improving its digestibility and soluble protein content may be a low-cost food supplement. However, due to its mineral imbalance, it is not recommended as the sole food source for ruminants.

Experimental investigation of molasses as a sole nutrient for the production of an alternative metabolite biosurfactant

In this study, sugarcane molasses was explored as a sole source of nutrients for the production of a value added product (biosurfactant) using an isolated strain Bacillus subtilis RSL-2. The biosurfactant production (maximum) was scrutinized by response surface methodology-central composite design (RSM-CCD), considering molasses as the carbon source (1–5 % w/v), pH (4–8) and temperature (25–45 °C), as the input parameters. At the optimized condition, remarkable biosurfactant concentration and surface tension were obtained as 12.34 ± 0.1 g/L and 24.09 ± 0.11 mN/m, respectively. The critical micelle concentration of the produced biosurfactant was found to be 80 mg/L. The produced biosurfactant was identified to be lipopeptide in nature and reduced the surface tension of water from 72.80 ± 0.5 mN/m to 24.09 ± 0.11 mN/m. The produced biosurfactant showed excellent surface activities, and thermal and colloidal stability. The present study endorsed the suitability of molasses as a suitable substrate (media) for the remarkable production of biosurfactant.

Preparation and characterization of bacterial cellulose produced from fruit and vegetable peels by Komagataeibacter hansenii GA2016

This study focused on the investigation of bacterial cellulose production potency of some fruit and vegetable peels (cucumber, melon, kiwifruit, tomato, apple, quince and pomegranate) with Komagataeibacter hansenii GA2016. Fruit and vegetable peels were hydrolyzed, used for bacterial cellulose (BC) production and their chemical, physical, thermal and structural features were compared to BC from Hestrin–Schramm medium (HSBC) and plant cellulose (CP). Except for pomegranate peel hydrolysate, all the fruit and vegetable peel hydrolysates supplied to K. hansenii GA2016 supported the BC production. Among the fruit and vegetable peel hydrolysates, the highest BC production was observed in kiwifruit peel hydrolysate (11.53%), while the lowest production was observed in apple peel hydrolysate (1.54%). Water-holding capacities of the BCs were ranged from 627.50% to 928.79% and higher than HSBC (609.30%), average fiber diameters were ranged from 47.64 nm to 61.11 nm and thinner than HSBC (74.29) and CP (10,420 nm), crystallinities were ranged from 80.27% to 92.96%, thermal capacities BCs were higher than HSBC and CP. For the BC productions, utilization of the fruit and vegetable peels as the sole nutrient source could reduce the production costs and among the polysaccharides, increase the use of BC in industry.

Deletion of bglC triggers a genetic compensation response by awakening the expression of alternative beta-glucosidase

In the plant pathogen Streptomyces scabies, the gene bglC encodes a GH1 family cellobiose beta-glucosidase that is both required for primary metabolism and for inducing virulence of the bacterium. Deletion of bglC (strain ΔbglC) surprisingly resulted in the augmentation of the global beta-glucosidase activity of S. scabies. This paradoxical phenotype is highly robust as it has been observed in all bglC deletion mutants independently generated, thereby highlighting a phenomenon of genetic compensation. Comparative proteomics allowed to identify two glycosyl hydrolases – named BcpE1 and BcpE2 – of which peptide levels were significantly increased in strain ΔbglC. Quantitative RT-PCR revealed that the higher abundance of BcpE1 and BcpE2 is triggered at the transcriptional level, the expression of their respective gene being 100 and 15 times upregulated. Enzymatic studies with pure BcpE proteins showed that they both possess beta-glucosidase activity thereby explaining the genotypic-phenotypic discrepancy of the bglC deletion mutant. The GH1 family BcpE1 could hydrolyze cellobiose and generate glucose similarly to BglC itself thereby mainly contributing to the survival of strain ΔbglC when cellobiose is provided as sole nutrient source. The low affinity of BcpE2 for cellobiose suggests that this GH3 family beta-glucosidase would instead primarily target another and yet unknown glucose-beta-1,4-linked substrate. These results make S. scabies a new model system to study genetic compensation. Discovering how, either the bglC DNA locus, its mRNA, the BglC protein, or either its enzymatic activity controls bcpE genes' expression, will unveil new mechanisms directing transcriptional repression.

Bacteria metabolites from Peganum harmala L. polysaccharides inhibits polyQ aggregation through proteasome-mediated protein degradation in C. elegans

Huntington's disease (HD) is a relentlessly progressive neurodegenerative disease featured by the over-expanded polyglutamine (polyQ)-induced protein aggregation. Using Caenorhabditis elegans (C. elegans) as a model system, we show that water soluble polysaccharide extracted from the herb Peganum harmala L. (PS1) not only reduces polyQ aggregation but also alleviates the associated neurotoxicity. Genetic and pharmacologic analysis suggested that PS1 treatment acts though proteasome-mediated protein degradation pathway to inhibit polyQ aggregation. Notably, the efficacy of PS1 is aroused specifically by co-incubation with live Escherichia coli OP50, which is the sole food source for worms. Further UPLC-Q-TOF/MS analysis determined the bioactivity of polyQ inhibition, which is composed of several oligosaccharides, including stachyoses, verbascoses, trisaccharides and tetrasaccharides composed of galacturonic acids. Together, our study revealed a potential drug target for further HD treatment and pinpointed the possibility that the secreted metabolites produced from bacteria treated with various compounds may provide direct beneficial effect to human bodies.

Effects of submerged liquid fermentation of Bacillus subtilis WX-17 using okara as sole nutrient source on the composition of a potential probiotic beverage.

This work aims to produce a functional probiotic beverage using okara as the sole nutrient source. Hence, okara was fermented with Bacillus subtilis WX‐17 in submerged liquid fermentation and the supernatant was tested. Metabolomic analysis showed that the nutritional profile of the beverage was enhanced after fermentation. Essential amino acids as well as short‐chain fatty acids were significantly (p < .05) upregulated. Total phenolic content and antioxidant content (in terms of DPPH radical scavenging activity) increased by 6.32 and 1.55 times, respectively. After 6 weeks, probiotic viability remains unchanged when stored at 4°C and the cell count is above the minimum dosage to confer health benefits. Antimicrobial activity was also detected against gram‐positive bacteria. The findings of this work showed the potential of submerged liquid fermentation of Bacillus subtilis WX‐17 using okara as sole substrate to produce a functional and low‐cost probiotic beverage.

Enhanced Functionality of Canavalia gladiata Hull by Fermentation with Lactic Acid Bacteria

Abstract Objectives Immature Canavalia Gladiata Hull (ICGH) has been used traditionally as food but the research data on its functionality is insufficient. Antioxidant and anti-inflammation activity of ICGH and fermentation was performed using lactic acid bacteria (LAB) with glycosidase activity to confirm whether the bioconversion affect the functionality. Methods LAB was screened from Kimchi for the glycosidase activity. Antioxidant activity was evaluated by ABTS, DPPH, cellular antioxidant activity (CAA), and nitrite oxide (NO) production was evaluated with RAW264.7 cell treated with lipopolysaccharide (LPS). Active component in ICGH was analyzed using HPLC-PDA, MS/MS, and NMR. Results LABs could grow in medium with ICGH as a sole nutrient source. After fermentation the contents of lactic acid was increased as sugar contents declined and asparagine and γ-aminobutyrate(GABA) were detected as main metabolite, and some flavonoids were identified. After fermentation, higher free radical scavenging activity was confirmed in ABTS and DPPH assay and the tendency to decrease in reactive oxygen species and nitrite production was found in a dose dependent manner. Conclusions The fermentation of ICGH with two selected strains enhanced the antioxidant activity and decreased NO production by increase in the bioavailability of active compounds in ICGH. Funding Sources National Institute of Agricultural Sciences.

Comparative Study of Intake, Apparent Digestibility and Energy and Nitrogen Uses in Sahelian and Majorera Dairy Goats Fed Hay of Vigna unguiculata.

Simple SummaryA specialized dairy goat like the Majorera (M) breed could be a good opportunity to meet the high demand for dairy products in Senegal. The efficiency of forage use from the M breed was therefore compared to that of the local Sahelian (S) breed. To this end, 6 M and 6 S goats were given a hay of a legume, Vigna unguiculata, as sole source of nutrient and their energy and nitrogen metabolism were studied. Forage intake was higher in the M goats but also their milk production. The efficiency with which energy and nitrogen was used was similar between the two breeds but M required more energy to meet its survival needs (energy for maintenance) and possibly less protein. Thus, it appears that M is probably better suited to dairy production systems requiring more attention from breeders.This study aimed to compare digestive and metabolic characteristics in Sahelian (S) and Majorera (M) goat breeds. Six lactating females from each breed, with an average weight 27.0 ± 1.93 and 23.7 ± 1.27 kg, respectively, were used. Cowpea hay, variety 58/74, was offered as sole feed ingredient, at a rate of 2 kg of fresh matter per animal per day. The animals were placed in metabolic cages and a digestibility test was conducted according to an adaptation period of 15 days and a collection period of 7 days. The daily chemical components offered and refused and recovered faeces, urine and milk were measured in order to assess energy and nitrogen utilization. The M and S goats had similar levels of dry matter (DM) intake as well as nutrient digestibility. On a metabolic weight basis, dry matter intake, gross energy intake, metabolizable and energy intake, digestible energy and energy lost as methane production were significantly higher (p < 0.01) in M than in S goats. Urinary energy excretion was similar (p = 0.9) between breeds, while faecal energy output was higher in M than in S goats. The milk energy output from the M goats was higher than that the S goats (p < 0.05). However, metabolizable to net energy conversion efficiency (klm) was not affected by breed (p = 0.37), while N intake, milk N yield and faecal N losses, relative to metabolic weight, were significantly higher (p < 0.05) in M than in S goats. Similarly, the percentage of dietary N intake excreted in urine (UNIN) was higher in S than in M breeds. The breed factor had no effect on N retained, N digestibility, urinary N and N use efficiency. In conclusion, the M and S goats were similar in terms of energy and nitrogen use efficiency, despite higher daily milk production and DM consumption in the M goat. This suggests that the M breed is possibly more dependent on a dense nutrition diet than the S breed but requires less maintenance nitrogen.

Efficient saccharification of microalgal biomass by Trichoderma harzianum enzymes for the production of ethanol

Microalgal and/or cyanobacterial biomass could be more advantageous than current plant feedstocks for the production of ethanol and/or other fermentation products. Enzymatic saccharification of microalgal biomass currently requires harsh pretreatments and significant amounts of expensive hydrolytic enzymes. The purpose of this study was: i) to analyze the quality of biomass of a cell-wall deficient microalga as a saccharification substrate for enzymatic hydrolysis; and ii) to identify an alternative source of enzymes for the saccharification of algal biomass. We showed that a newly isolated strain of the fungus Trichoderma harzianum was able to grow at the expense of intact cells of the alga Chlamydomonas reinhardtii as a sole source of nutrients. The fungal spent medium exhibited pectinolytic, amylolytic, cellulolytic, and proteolytic activities and efficiently saccharified either dry and milled biomass or intact cells of the microalga. Biomass of a cell-wall deficient C. reinhardtii strain was saccharified at a similar efficiency than biomass of the parental strain with T. harzianum enzymes, indicating full capacity of these enzymes to circumvent the cell-wall recalcitrance to hydrolysis. Algal biomass saccharification yielded up to 22.4 g reducing sugars·L−1 and could be quantitatively converted into ethanol by fermentation with Saccharomyces cerevisiae. The efficiency of conversion of algal biomass into ethanol showed in this study is among the highest reported so far and encourages research for scaling up production of T. harzianum enzymes as well as the evaluation of biomass of other algal strains as feedstocks for the production of ethanol.

A Nutritional and Environmental Analysis of Local Food Pantries Accessible to College Students in Rural North Carolina.

IntroductionFood insecurity is a growing concern among college students and is especially prevalent in rural areas. Food pantries often serve as a resource to food insecure individuals yet, their policies, standards, and nutritional quality vary due to the unpredictability of food donations.PurposeTo examine the nutritional quality of food items and adherence of best practices at local food pantries accessible to college students near a university in rural Appalachia.MethodsThree food pantries in North Carolina were selected due to their proximity to a local, rural university. Food items were analyzed for nutrient and food group content and compared to national recommended standards for a moderately active 20-year-old male student. Food pantry environments were analyzed using the Healthy Food Pantry Assessment Tool (HFPAT).ResultsAll pantries scored in acceptable ranges (39, 59, and 60) on the HFPAT. Food pantries provided 38% of total daily calories and below recommended daily levels for vitamin C (27%), vitamin D (5%), potassium (29%), and calcium (38%), but above recommended levels for sugar (220%), and trans-fat (342%). When all the food from food pantries were combined, they still did not meet food group recommendations, providing: 25% fruit, 50% vegetable, 9% grain, 15% protein, and 20% dairy servings over a 14-day period.ImplicationsIn general, students who rely on food pantries as their sole source of food do not reach recommend levels for nutrients or food groups. Interventions, programs, and/or policies which increase the healthfulness of food pantry items are warranted to improve the quality of food available to food insecure college students.

Dynamic terminal investment in male burying beetles

The dynamic terminal investment threshold model posits that the propensity of an individual to terminally invest in response to an immediate survival threat, such as an infection, depends on other factors that alter an individual's residual reproductive value. Here, we explore the potential for dynamic terminal investment in burying beetles, insects that inter small vertebrate carcasses as the sole source of food for their offspring and that exhibit extensive biparental care. We injected males at two different ages with heat-killed bacteria and measured their reproductive output, predicting that immune-challenged males would show a longer period of parental care, consume less of the carcass and produce a greater number of larvae in the current reproductive attempt compared with control males. We further predicted that terminal investment would be more evident in older males than in younger ones. Males challenged with heat-killed bacteria as virgins prior to their first reproductive attempt showed no evidence of terminal investment, whereas these same individuals when challenged at a later age as reproductively experienced breeders in a subsequent reproductive attempt showed increased reproductive output. Older, immune-challenged individuals gained less mass during the time on the carcass than control males, suggesting that this terminal investment was subsidized, at least in part, by males refraining from eating as much of the carcass as they might have otherwise done in the absence of an immune challenge, leaving more carrion for their offspring to consume at the expense of their own maintenance and future reproduction. Because it seems likely than an individual's residual reproductive value decreases with both increasing age and reproductive experience, the context-specific terminal investment shown by immune-challenged males in the current study aligns with theory.

Efficient bioconversion of waste bread into 2-keto-d-gluconic acid by Pseudomonas reptilivora NRRL B-6

Development of bioprocess routes for production of value-added materials from food waste is very attractive in terms of bioprocess economics and environmental protection. In this study, production of 2-keto-d-gluconic acid, a significant platform chemical, from food waste was performed by Pseudomonas reptilivora NRRL B-6 for the first time. The nitrogen source preference of the strain for 2-keto-d-gluconic acid production under different glucose concentrations in synthetic medium has been elucidated. At higher glucose concentrations, utilization of organic nitrogen source (yeast extract) led to higher product formation while at lower glucose concentration, utilization of inorganic nitrogen source (ammonium chloride) was also very feasible. The results indicated that favorable nitrogen source for 2-keto-d-gluconic acid production can change depending on the glucose concentration. The waste bread hydrolysate (glucose 181.43 g/L, protein 1.21% (w/v)) prepared by sequential application of α-amylase, amyloglucosidase, and protease was utilized in medium formulation at different glucose concentrations. Bread hydrolysate without additional supplements provided higher product formation than the optimum medium prepared with the hydrolysate. Utilization of 50 g/L CaCO3 led the maximum product formation. The maximum 2-keto-d-gluconic acid production from waste bread was 142.81 g/L with the productivity of 3.02 g/L/h and molar yield of 0.95. The proposed approach in this study confirms that waste bread as a sole source of nutrients can be valorized for microbial production of various industrially relevant platform chemicals.

Contribution of males to brood care can compensate for their food consumption from a shared resource.

The sharing of the same food source among parents and offspring can be a driver of the evolution of family life and parental care. However, if all family members desire the same meal, competitive situations can arise, especially if resource depletion is likely. When food is shared for reproduction and the raising of offspring, parents have to decide whether they should invest in self‐maintenance or in their offspring and it is not entirely clear how these two strategies are balanced. In the burying beetle Nicrophorus vespilloides, parents care for their offspring either bi‐ or uniparentally at a vertebrate carcass as the sole food source. The question of whether biparental care in this species offers the offspring a better environment for development compared with uniparental care has been the subject of some debate. We tested the hypothesis that male contribution to biparental brood care has a beneficial effect on offspring fitness but that this effect can be masked because the male also feeds from the shared resource. We show that a mouse carcass prepared by two Nicrophorus beetles is lighter compared with a carcass prepared by a single female beetle at the start of larval hatching and provisioning. This difference in carcass mass can influence offspring fitness when food availability is limited, supporting our hypothesis. Our results provide new insights into the possible evolutionary pathway of biparental care in this species of burying beetles.

A novel lipolytic yeast Meyerozyma guilliermondii: Efficient and low-cost production of acid and promising feed lipase using cheese whey

Abstract Cheese whey is a by-product of the dairy industry that is generated in large quantities. It is considered the main pollutant in dairy wastewaters due to its high organic load. The aim of this paper was to produce lipases using cheese whey as the sole nutrient source. Yeasts isolated from slaughterhouse fridge effluent and oil mill effluent were screened for lipolytic activities. The lipase activity of the target yeast strain was increased by improving the culture conditions using a statistical design and the lipase activity was biochemically characterized. Among 25 yeasts, the L1 strain, identified by molecular markers as Meyerozyma guilliermondii, was selected as a good lipase producer. The best results were obtained when M. guilliermondii was grown in 2.0% of cheese whey at pH 4.0 for 24 h. Under these optimal conditions, a 6.7-fold increase of lipase production was achieved, corresponding to the production of 285.82 U mL−1, which is higher than others reported in the literature. Biochemical characterization revealed that M. guilliermondii lipase was more active and stable at 35–40 °C and in acidic conditions (pH 2.5–5.5). It also exhibited remarkable stability in organic solvents, especially those of a hydrophobic nature and excellent tolerance to digestive components. The novel isolate M. guilliermondii showed potential for use in feed industry thank to its ability to produce acid lipases efficiently and at a low cost using an abundant and polluting waste material.

High-throughput screening of environmental polysaccharide-degrading bacteria using biomass containment and complex insoluble substrates

Carbohydrate degradation by microbes plays an important role in global nutrient cycling, human nutrition, and biotechnological applications. Studies that focus on the degradation of complex recalcitrant polysaccharides are challenging because of the insolubility of these substrates as found in their natural contexts. Specifically, current methods to examine carbohydrate-based biomass degradation using bacterial strains or purified enzymes are not compatible with high-throughput screening using complex insoluble materials. In this report, we developed a small 3D printed filter device that fits inside a microplate well that allows for the free movement of bacterial cells, media, and enzymes while containing insoluble biomass. These devices do not interfere with standard microplate readers and can be used for both short- (24–48 h) and long-duration (> 100 h) experiments using complex insoluble substrates. These devices were used to quantitatively screen in a high-throughput manner environmental isolates for their ability to grow using lignocellulose or rice grains as a sole nutrient source. Additionally, we determined that the microplate-based containment devices are compatible with existing enzymatic assays to measure activity against insoluble biomass. Overall, these microplate containment devices provide a platform to study the degradation of complex insoluble materials in a high-throughput manner and have the potential to help uncover ecologically important aspects of bacterial metabolism as well as to accelerate biotechnological innovation.