Inoculum Combinations Research Articles

Microbiological, sensory, and chemical properties of high-quality tempeh made with instant Mosaccha tempeh inoculum powder.

The combination of Saccharomyces cerevisiae and Rhizopus oligosporus liquid inoculum has been successfully used to ferment soybeans into tempeh that contains β-glucan. However, using the liquid inoculum of these two microbes as a starter is impractical; so, developing an instant tempeh dry inoculum in powdered form, called the Mosaccha inoculum powder, for ease of use is necessary. This study aimed to determine the best concentration of instant Mosaccha inoculum powder to produce high-quality Mosaccha tempeh. The study used a Complete Randomized Block Design with seven different levels of instant Mosaccha inoculum powder percentage, ranging from 0.3% to 1.8% (w/w). A commercial tempeh inoculum, RAPRIMA, amounting to 0.2%, was used as control. Then, the microbiological (total mold and total yeast) and sensory (color, aroma, texture, and taste) properties were evaluated. The data obtained was analyzed statistically using analysis of variance (ANOVA) and Honestly Significant Difference (HSD) tests at the 5% level. The results showed that the percentage of instant Mosaccha inoculum powder significantly affected the microbiological and sensory properties of Mosaccha tempeh. A concentration of Mosaccha inoculum powder between 0.6% to 1.8% could produce good quality Mosaccha tempeh, but the best Mosaccha tempeh was produced with 1.5% instant Mosaccha inoculum powder, which met the Indonesian National Standards (SNI) 3144:2015, had a very favorable taste, and contained 0.49% β-glucan. Therefore, Mosaccha inoculum in powdered form can be developed and used as a starter in making high-quality tempeh that contains β-glucan.

Effect of Hanseniaspora vineae and Saccharomyces cerevisiae co-fermentations on aroma compound production in beer

In recent years, the boom of the craft beer industry refocused the biotech interest from ethanol production to diversification of beer aroma profiles. This study analyses the fermentative phenotype of a collection of non-conventional yeasts and examines their role in creating new flavours, particularly through co-fermentation with industrial Saccharomyces cerevisiae. High-throughput solid and liquid media fitness screening compared the ability of eight Saccharomyces and four non-Saccharomyces yeast strains to grow in wort. We determined the volatile profile of these yeast strains and found that Hanseniaspora vineae displayed a particularly high production of the desirable aroma compounds ethyl acetate and 2-phenethyl acetate. Given that H. vineae on its own can't ferment maltose and maltotriose, we carried out mixed wort co-fermentations with a S. cerevisiae brewing strain at different ratios. The two yeast strains were able to co-exist throughout the experiment, regardless of their initial inoculum, and the increase in the production of the esters observed in the H. vineae monoculture was maintained, alongside with a high ethanol production. Moreover, different inoculum ratios yielded different aroma profiles: the 50/50 S. cerevisiae/H. vineae ratio produced a more balanced profile, while the 10/90 ratio generated stronger floral aromas. Our findings show the potential of using different yeasts and different inoculum combinations to tailor the final aroma, thus offering new possibilities for a broader range of beer flavours and styles.

The effect of indigenous Arbuscular mycorrhizal fungi (AMF) on phyto-accumulation in Carica papaya hybrids

Papaya (Carica papaya L.) is a climacteric fruit with a resilient and distinctive aroma. The consumption of the fruit is global due to its high nutritive and medicinal values. However, there has been low production of quality papaya fruits due to unavailability of crucial mineral elements in the soils. The current study therefore, focuses on the effect of indigenous arbuscular mycorrhizal fungi (AMF) as a biofertilizer on the quality of papaya fruits. In order to verify AMF effectiveness on papaya fruits, four treatments were used: AMF inoculum only, composted farm yard manure (FYM) only, combination of AMF inoculum and compost FYM and control where only soil and sand media were used at a ratio of 1:1. Jomo Kenyatta University of Agriculture and Technology (JKUAT) and Malkia papaya hybrids were used. The papaya seeds from JKUAT and Malkia papaya hybrids were sown in trays and transplanted at 3 leaves stage into 5 litre pots within a green house. The AMF spores were bulked using sorghum plants to obtain the AMF inoculum. The treatments were added into the soil media of the papaya plantlets at a ratio of 1:3, every 4 weeks after first transplanting until they were 20 weeks old. They were then transplanted to 100 litre containers, where completely randomized design was used and replication of six papaya plants for each treatment and hybrid. Watering, weeding and cooling the green house with water fumes was carried out when necessary; as the papaya plants grew until the fruits attained physiological maturity. The fruits were separately harvested and ripened to a predetermined stage. They were then analysed for moisture content, crude fibre, minerals (nitrogen, phosphorous, potassium, magnesium, calcium, iron and zinc), ascorbic acid, total carotenoids and total polyphenols. Data obtained was subjected to two-way ANOVA at p ≤ 0.05 significance level; means were separated using Tukey's HSD test in Genstat's 15th edition. JKUAT hybrid with AMF inoculum treatment had 3.07%crude fibre and 8.42mg/100g phosphorous content while JKUAT hybrid with both AMF inoculum and manure treatments had 4.9 % crude fibre and 9.88 mg/100g phosphorous content. Malkia and JKUAT hybrids with compost FYM treatment had potassium content of 98.31mg/100g and 109.4 mg/100g respectively while the controls had 31.58 mg/100g and 35.32mg/100g respectively. Incorporating soil media with manure and AMF inoculum improved the nutritive quality of papaya fruits and this was contingent on papaya hybrids. Key words: biofertilizer, inoculum, mineral elements, nutritive quality, physiological maturity

Effects of combinations of arbuscular mycorrhizal fungal species on tomato growth and Fusarium wilt control

In this study, we investigated the effects of combinations of arbuscular mycorrhizal (AM) fungal species on tomato seedling growth and Fusarium wilt control. The study was conducted in greenhouse pot experiments using the tomato (Solanum lycopersicum) variety Fusan 88 and the fungi Funneliformis mosseae, Diversispora versiformis, Claroideoglomus etunicatum, and Rhizophagus intraradices as inoculants. The results showed higher mycorrhizal root colonization rates in all inoculation mixtures than in single-inoculum treatments, while growth-promotion effects differed significantly among AM fungal species and their combinations. Except for inoculation with F. mosseae alone, other inoculation treatments significantly promoted the growth of tomato seedlings. Of all fungal species, R. intraradices had the most significant effect on promoting seedling growth, as observed in all inoculum combinations containing this species. The greatest effect on seedling growth was observed for combined inoculation with D. versiformis + R. intraradices, which led to increases in above- and belowground biomass of 67.74 % and 100 %, respectively, compared to the control (CK), followed by C. etunicatum + R. intraradices, which led to increases in above- and belowground biomass of 61.29 % and 100 % compared to CK. Redundancy analyses showed that compared to the other three species, R. intraradices had more significant effects on promoting plant nitrogen, phosphorus, and potassium uptake and increasing above- and belowground dry weight. Mycorrhizalized seedlings were more resistant to Fusarium wilt and had lower malondialdehyde content and higher catalase, superoxide dismutase, and polyphenol oxidase activity in tomato plants. The lowest Fusarium wilt disease index value was 39.96 %, for mixed inoculation with F. mosseae + D. versiformis + C. etunicatum; this was 34.28 % lower than that of CK, and the control effect was 34.27 %, followed by inoculation with C. etunicatum + R. intraradices, which had a disease index value of 41.48 %, 31.78 % lower than that of CK, with a control effect value of 31.76 %. Therefore, we transplanted tomato seedlings inoculated with C. etunicatum + R. intraradices, which had both good growth-promotion and disease-resistance effects, to a greenhouse for sand culture under conditions of high water and fertilization. The mycorrhizal relationships developed in these plants at the seedling stage remained stable throughout the tomato reproductive period. The mycorrhizal seedlings had a significantly lower incidence of Fusarium wilt and lower disease index values, indicating better disease control than observed in non-mycorrhizal seedlings. The mycorrhizal plants produced fruits with a significantly higher soluble-sugar content and sugar:acid ratio (30.8 % and 42.3 % higher, respectively, than CK) and a significantly lower organic acid content (11.5 % lower than CK). Thus, mycorrhization significantly improved tomato plants’ growth, disease resistance, and fruit quality. These findings lay a foundation for the application of mycorrhizal fungi in tomato agriculture.

Invader-induced soil abiotic and biotic conditions have little impact on the competitive interactions between a native and an invasive legume

• No competition occurred between native Psoralea pinnata and invasive A. saligna . • Each legume species associated with different rhizobia and used divergent nitrogen sources. • Australian rhizobia were naturally present in pristine Fynbos soils. • Acacia invasion and spread may not be limited by rhizobium availability in Fynbos soils. Invasive Australian acacias cause substantial biodiversity impacts in South Africa's Core Cape Subregion (CCR) via positive plant-soil feedbacks, driven by high growth rates and leaf litter input by these legumes and their associations with nitrogen-fixing rhizobia. However, it is unclear whether acacia-induced soil abiotic conditions, or the association between acacias and different types of rhizobia, or both, are driving the invasive performance of acacias. Here we aim to determine how familiar (i.e., Australian) vs. novel (i.e., South African) rhizobium associations and acacia leaf litter affect competition between the invasive Acacia saligna (Labill.) H.L.Wendl. and native Psoralea pinnata L.. We grew these two legumes alone and together in pots containing Psoralea -conditioned soils. Seedlings grown alone were subjected to Australian bradyrhizobia inoculum treatments, while seedlings grown in mixture received a combination of inoculum and topsoil conditioned by acacia leaf litter in a fully factorial design. We found that neither the addition of Australian rhizobia, nor acacia-conditioned topsoil, enhanced the performance of A. saligna . Surprisingly, these treatments also did not hinder P. pinnata ’s performance relative to that of A. saligna . Next generation sequencing (NGS) data revealed that each legume species associated with distinct (and familiar) rhizobia, regardless of inoculum treatment. Acacia saligna primarily met its nitrogen requirements by utilising soil nitrogen, while P. pinnata obtained much of its nitrogen via biological fixation. This apparent differentiation in nitrogen acquisition, coupled with the unique rhizobial associations of the two species, may explain the absence of strong asymmetric competition between them. This may also explain why P. pinnata is able to persist under Acacia invasion in the field and suggests that this native legume is a good candidate for restoring acacia-invaded habitats.

Effect of Different Organic and Inorganic Inputs on Growth and Yield of Soybean (Glycine max) in Southeastern Nigeria

This study was carried out at the teaching and Research farm, Department of Horticulture and Landscape Technology, Akanu Ibiam Federal Polytechnic, Unwana, to investigate the integrated effects of organics (lime, Inoculum) and mineral fertilizers, (single superphosphate and muriate of potash) on the growth, nodulation and yield of soybean. The input omission trial was composed of 16 treatment combinations of phosphorus (75 kg/ha), potassium (88 kg/ha), lime (1500 kg/ha), and inoculum (400g/100kg seed). Each set of 16 treatments were randomized and replicated 3 times. The soybean variety “TGX1951-3F” was planted in 0.5 m by 1 m plots with a seed spacing of 5 cm. Data on number of nodules and nodule viability at 45 days after planting, plant height at 90 days after planting, number and weight of 100 seeds per plot and yield per plot at harvest were collected and analyzed using Analysis of Variance (ANOVA) in R using the package “car” to test the main treatment effects, 2-way, 3-way, and 4-way treatment interactions in the omission trial. Results showed highly significant effects of treatments on the growth, nodulation and yield of soybean. The no input treatment generally had the most appreciable improvement in plant height, nodule viability, weight of 100 seeds and yield. Inoculated seeds had the highest number of nodules and percent nodule viability (5 and 69% respectively). . 2.12ton/ha yield generated by the no input treatment shows the potential for future higher yield especially when climatic and good agronomic strategies are employed.

Efficacy of Selected Powdered Floor Treatments against Salmonella, Escherichia coli, and Listeria Monocytogenes on Polyurethane-Concrete Flooring Material Carriers

Food processing environment flooring can become contaminated with pathogens in many ways including foot and equipment traffic, incoming materials, and floor drain backups. Natural antimicrobial turmeric and commercially available powdered floor treatments may reduce the levels of pathogens on flooring thereby reducing the risk of cross contamination from the floor to food contact surfaces. These chemicals were evaluated to determine their effectiveness against cocktails of Salmonella , Escherichia coli , and Listeria monocytogenes dried onto the surfaces of carriers made from polyurethane-concrete commercial flooring material. Aqueous test solutions were prepared from the minimum treatment required per m 2 from the manufacturer's instructions diluted in sterile water. Potential synergy between turmeric and a percarbonate based commercial floor treatment was explored with a mixture of turmeric and sodium percarbonate, each at approximately 37g/m 2 application rate. Each inoculated carrier was exposed to the treatment solutions or a sterile water control for 10 minutes at room temperature, neutralized with Hi-Cap neutralizing broth, the bacteria suspended, enumerated, and log 10 reductions calculated for each treatment and inoculum combination. Mean log 10 CFU/carrier reductions with standard deviations ranged between 4.29±0.34 for the sodium percarbonate (SPC) based treatment and 0.004±0.23 for turmeric for Salmonella , 4.81±0.16 for SPC based treatment and -0.16±0.62 for turmeric for E. coli , and 4.88±0.6 for SPC based treatment and -0.16±0.15 for turmeric for L. monocytogenes .

Traversing arbuscular mycorrhizal fungi and Pseudomonas fluorescens for carrot production under salinity.

Carrot is a vital supply of dietary fiber, vitamins, and carotenoids, and it is also rich in antioxidants and minerals. Soil salinity significantly reduces the yield and quality of carrots. Mycorrhiza inoculum (AMF) is known to improve morphological and biochemical traits of vegetables even under saline conditions. But the role of AMF in combating soil salinity effect in carrot is not studied in detail. Therefore here, in the first set, carrot seeds are inoculated with microbes in a pot experiment under polyhouse condition. In total, we applied 7 treatments with different combinations of Mycorrhiza inoculum (Glomus mosseae (Gm) and Gigaspora gigantea (Gg)) and phosphate solubilizing bacteria (Pseudomonas fluroscens (Pf)). In pot experiment study the best two treatments were the combination of Gm + Pf + GG and Pf + GG. Both of these treatments were selected for validation under the open field conditions. Primarily, there seems to be a promising opportunity for AMF application to carrots under pot culture as well as under field trials because of promising effect towards morphological parameters, especially root weight, and disparities in nutrients and metabolites. Overall, our study highlights mycorrhizal fungi and other microbes' efficacy in achieving a successful carrot production under salinity stress.

Effect of Activated Cow Dung as Inoculum on Methane Production of Steam-Exploded Rice Husks

To investigate methane production from a single substrate with steam explosion pretreatment and activated cow dung as natural resources for cellulolytic microflora to enhance biogas production from agricultural biomass waste. The recalcitrant of the lignin-carbohydrate complex (LCC) of rice husk was dismounted using a steam explosion pretreatment at 2.53 MPa (224 °C) for 5 and 7 min of steaming time, followed with and without water extraction. All the residue from the extraction process, either solid or liquid, was used for the biogas feedstock. Anaerobic digestion (AD) was conducted under mesophilic condition at 37 °C with two different inoculums: sludge and a mixed inoculum containing sludge and activated cow dung. The predicted methane production was calculated using the stoichiometric formula. The steam explosion pretreatment and mixed inoculum significantly enhanced the cumulative methane production. The 7-min steaming time led to the breaking up of 41% cellulose, and 199 ml/g of methane was produced from the total cumulative methane yield of the solid and liquid feedstock, with a 96.1% yield of the predicted methane amount. The enhancement of methane production was achieved using a combination of steam explosion pretreatment and mixed inoculum between sludge and activated cow dung.

Micorrizas y fertilización: efecto en la producción de Pinus engelmannii Carr. en vivero

Introduction: In the nursery, controlled-release fertilization and inoculation with mycorrhizal fungi promote the quality of plant material reproduced in containers. Objective: To evaluate the effect of two commercial mycorrhizal inoculants and one controlled-release fertilizer on the development of Pinus engelmannii Carr. in nursery. Materials and methods: Two commercial inoculants (fungi native to Mexico [1 mL·plant-1 with 1.05 x 107 spores·mL-1] and exotics [1.5 mL·plant-1 with 6.5 x 106 spores·mL-1]), two doses of a controlled-release fertilizer (11-28-11 NPK [3 and 6 g·L-1]) and a control were evaluated; in total, nine treatments were used. The variables analyzed were: survival, stem height, root collar diameter, wet and dry biomass, ratio of dry biomass of the aerial part/dry biomass of the root part, lignification index, Dickson’s quality index and mycorrhizal colonization. Results and discussion: Survival (80 to 96 %) was similar between treatments. Eight months after sowing, seedlings showed significant differences (P ≤ 0.05) in morphological variables; combined treatments gave better results. Plants with commercial inoculum of native fungi (1 mL·plant-1 [Amanita rubescens Pers., Amanita sp., Lactarius indigo [Schwein] Fr., Ramaria sp. and Boletus sp.]) and fertilization of 3 g·L-1 had higher Dickson quality index. It was observed that the higher the fertilization dose, the lower the percentage of mycorrhizal colonization. Conclusion: The combination of ectomycorrhizal inoculum of native fungi and low-dose fertilization showed that both components are complementary in the plant development of P. engelmannii.

Bio-Methane Production via Anaerobic Co-Digestion by Optimizing the Mixing Ratios of River Tamarind (Leucaena leucocephala) and Dolphin Fish (Coryphaena hippurus) Offal

Fish offal and other high protein substrates are generally not suitable for anaerobic digestion because of the high levels of ammonia produced as a result of their biodegradation. In order to efficiently use these types of substrates to produce methane, co-digestion is used to balance the amounts of carbon and nitrogen in the feedstock. In this experiment an optimization procedure for maximizing the methane potential of fish offal, using river tamarind as the co-substrates was developed. Our experimental design tested the effects of substrate to substrate mixtures, as well as overall substrate to inoculum combinations, on the methane potentials. This was performed using batch style biochemical methane potential assays, which employed a methodology developed in our laboratory. The optimum of the 25 combinations tested was 50% fish offal to 50% river tamarind at a substrate to inoculum ratio of 0.03, with a specific methane yield of 144 ± 6 NmL/gFM (330 ± 14 NmL/goDM). This gave much improvement when compared with the fish offal alone, which reached 63 ± 4 NmL/gFM (317 ± 20 NmL/goDM) at maximum. These results indicate that with the correct mixture, rivertamarind is a suitable co-substrate for anaerobic co-digestion of fish offal.

Study of fermented feed by mixed strains and their effects on the survival, growth, digestive enzyme activity and intestinal flora of Penaeus vannamei

In this study, the mixed strains, including Lactobacillus plantarum (STBL1), Saccharomyces cerevisiae (STBS1), and Bacillus safensis (SQVG18) were applied to the solid-state fermentation of commercial feed for Penaeus vannamei. Firstly, the optimum combination of strain inoculum, optimum fermentation conditions, and nutritional quality of the fermented feeds were investigated. It was noted that the acid-soluble protein and the content of amino acids (lysine, methionine, etc.) were remarkably improved in the feeds by solid-state fermentation with the optimum combination of STBL1: STBS1: SQVG18 = 1: 3: 3. Secondly, a six-week feeding experiment was performed using one control diet without probiotics (D0: 0 CFU g−1) and three fermented diets containing different concentrations of the optimum mixed-strain combination (D1: 107 CFU g−1; D2: 108 CFU g−1; D3: 109 CFU g−1). Shrimps fed D2, and D3 groups exhibited significantly better growth performance and activities of antioxidant enzymes and digestive enzymes than shrimp of other groups (P < .05). The fermented feeds also affected the intestinal microflora of P. vannamei at the end of the feeding trial. The diversity indices, composition, and functional prediction of microbial communities showed that shrimp fed D1 and D2 groups had a better microecological environment in intestines. Overall, the fermented diet with mixed strains of 108 CFU g−1 may be conducive to the growth and health of P. vannamei by improving growth, antioxidant capacity, digestion, and gut microflora.

Medium Optimization for Antimicrobial Production By Newly Screened Lactic Acid Bacteria

Lactic acid bacteria (LAB) are important for prevention of spoilage and pathogenic bacterial growth in foods due to their ability to generate antimicrobial substances. The objective of this study was to screen LAB for antimicrobial activity and to optimize culture medium for antimicrobial production using Response Surface Methodology (RSM) with Central Composite Design (CCD). Optimization of antimicrobial production of selected LAB was conducted with different combinations of glucose, NaCl, inoculum, and temperature. Our experimental results showed that from 129 LAB isolates, 55 showed significant inhibition against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Aspergillus niger, and Candida albicans. No isolates inhibited the growth of Aspergillus flavus. Lactobacillus plantarum LIPI13-2-LAB011 was selected for further study on culture medium optimization to inhibit the growth of C. albicans. From statistical analysis, the production of antimicrobial substances was significantly influenced by temperature, NaCl, and concentration of glucose. Furthermore, the optimum concentrations of glucose, concentration of inoculum, temperature, and NaCl were 1.63 %, 3.03%, 33.74°C, and 3.4%, respectively, with a maximum predicted inhibition index of 1.916, which increased 3.56-fold compared to that obtained in medium before optimization processes. The result was confirmed as when the optimum concentration of nutritions used, the inhibition index increased 3.12-fold.

Effect of Different Inoculum Combination on Biohydrogen Production from Melon Fruit Waste

The natural microbial consortium from many sources widely used for hydrogen production. Type of substrate and operating conditions applied on the biodigesters of the natural consortium used as inoculum impact the variation of species and number of microbes that induce biogas formation, so this study examined the effect of different inoculum source and its combination of biohydrogen production performance. The hydrogen producing bacteria from fruit waste digester (FW), cow dung digester (CD), and tofu waste digester (TW) enriched under strictly anaerobic conditions at 37OC. Inoculums from 3 different digesters (FW, CD, and TW) and its combination (FW-CD, CD-TW, FW-TW, and FW-CD-TW) were used to test the hydrogen production from melon waste with volatile solids (VS) concentration of 9.65 g/L, 37°C and initial pH 7.05 ± 0.05. The results showed that individual and combined inoculum produced the gas comprising hydrogen and carbon dioxide without any detectable methane. The highest cumulative hydrogen production of 743 mL (yield 207.56 mL/gVS) and 1,132 mL (yield 231.02 mL/gVS) was shown by FW and FW-CD-TW, respectively. Butyric, acetate, formic and propionic were the primary soluble metabolites produced by all the cultures, and the result proves that higher production of propionic acid can decrease hydrogen yield. Clostridium perfringens and Clostridium baratii prominently seen in all single and combination inoculum. Experimental evidence suggests that the inoculum from different biodigesters able to adapt well to the environmental conditions and the new substrate after a combination process as a result of metabolic flexibility derived from the microbial diversity in the community to produce hydrogen. Therefore, inoculum combination could be used as a strategy to improve systems for on-farm energy recovery from animal and plant waste to processing of food and municipal waste.Article History: Received February 5th 2018; Received in revised form May 7th 2018; Accepted June 2nd 2018; Available onlineHow to Cite This Article: Amekan, Y., Wangi, D.S.A.P., Cahyanto, M.N., Sarto and Widada, J. (2018) Effect of Different Inoculum Combination on Biohydrogen Production from Melon Fruit Waste. Int. Journal of Renewable Energy Development, 7(2), 101-109.https://doi.org/10.14710/ijred.7.2.101-10

Medium Optimization for Antimicrobial Production By Newly Screened Lactic Acid Bacteria

Lactic acid bacteria (LAB) are important for prevention of spoilage and pathogenic bacterial growth in foods due to their ability to generate antimicrobial substances. The objective of this study was to screen LAB for antimicrobial activity and to optimize culture medium for antimicrobial production using Response Surface Methodology (RSM) with Central Composite Design (CCD). Optimization of antimicrobial production of selected LAB was conducted with different combinations of glucose, NaCl, inoculum, and temperature. Our experimental results showed that from 129 LAB isolates, 55 showed significant inhibition against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Aspergillus niger, and Candida albicans. No isolates inhibited the growth of Aspergillus flavus. Lactobacillus plantarum LIPI13-2-LAB011 was selected for further study on culture medium optimization to inhibit the growth of C. albicans. From statistical analysis, the production of antimicrobial substances was significantly influenced by temperature, NaCl, and concentration of glucose. Furthermore, the optimum concentrations of glucose, concentration of inoculum, temperature, and NaCl were 1.63 %, 3.03%, 33.74°C, and 3.4%, respectively, with a maximum predicted inhibition index of 1.916, which increased 3.56-fold compared to that obtained in medium before optimization processes. The result was confirmed as when the optimum concentration of nutritions used, the inhibition index increased 3.12-fold.

Sustainable utilisation of Eppawala Rock Phosphate mediated by Phosphate Solubilizing Microbes: A timely action

Eppawala Rock Phosphate (ERP) reservoir is the major phosphate mineral resource in Sri Lanka which is recommended only for perennial crops such as pepper, a highly priced export agricultural crop. Since ERP is a non-renewable resource it is important to investigate methods for sustainable utilisation while improving the plant phosphorus (P) nutrition. Hence this study was aimed at the sustainable utilization of ERP applied for pepper with the assistance of native Phosphate Solubilising Microorganisms (PSMs); Aspergillus sp. and Burkholderia sp. which have the potential of solubilizing ERP in a cheap and environmental friendly manner. A pot experiment for pepper was carried out with three inoculum levels i.e. Aspergillus sp. alone (F), Burkholderia sp. alone (B) and the combination of both species (FB), and three fertilizer levels i.e. no P (P0), ERP at recommended level (P1) and ERP at half recommended level (P½). The treatments contained the combinations of inoculum and fertilizer level i.e. FP0, FP1, FP½, BP0, BP1, BP½, FBP0, FBP1, FBP½ and their counterparts with no inoculum, while P0, P1 (recommendation), P½ served as controls. All the treatments had Urea and Muriate of potash at the recommended level. The inocula, Aspergillus sp. and Burkholderia sp. were prepared in two different mass cultivation media i.e. rice straw supplemented with broken maize seeds at a ratio of 2:1 and rice straw supplemented with rice bran at a ratio of 1:1, respectively. Treatments were applied for 8 months old plants and completely randomized design was employed. Plant growth parameters: shoot dry weight and root dry weight and available soil P, plant P uptake and soil microbial counts were quantitatively determined by destructive sampling of 4 replicates. Three destructive sampling sessions (DS) were done at 10 week time intervals; where the first destructive sampling was done after 10 weeks of inoculation. The results obtained were statistically analyzed using one way ANOVA at 5% level of significance. Plant growth parameters were not significantly different. However, soil P levels were significantly different (p≤0.05). At 1st DS the treatments having both fungal and bacterial inocula showed the highest soil P and plant P uptake. At 2nd DS Aspergillus sp. was more persistent in soil than Burkholderia sp., hence the highest soil P and plant P uptake was observed in the treatments having only the fungal inoculum. Similar trend was observed at 3rd DS as well. In each of these instances (with PSMs) the available soil P levels were significantly high compared to the recommendation (P1). It was also observed that P½ along with PSMs showed similar performance when compared to P1 with PSMs. This concludes that the PSM inoculation facilitates the reduction of ERP application while improving the plant P nutrition which will ultimately lead towards the sustainable utilization of ERP. Keywords: Eppawala Rock Phosphate (ERP), Phosphate Solubilising Microorganisms (PSMs), Pepper

Microbial Fermentation of Organic Carbon Substrates Drives Rapid pH Neutralization and Element Removal in Bauxite Residue Leachate.

Globally, mineral processing activities produce an estimated 680 GL/yr of alkaline wastewater. Neutralizing pH and removing dissolved elements are the main goals of wastewater treatment prior to discharge. Here, we present the first study to explicitly evaluate the role of microbial communities in driving pH neutralization and element removal in alkaline wastewaters by fermentation of organic carbon, using bauxite residue leachate as a model system, and evaluate the effects of organic carbon complexity and microbial inoculum addition rates on the performance of these treatment systems at laboratory scale. Rates and extents of pH neutralization were higher in bioreactors fed with simpler organic carbon substrates (glucose and banana: 6 days to reach pH ≤ 8) than those fed with more complex organic carbon substrates (eucalyptus mulch: 15 days to reach pH ≤ 8; woodchips: equilibrium pH around 9). Concentrations of dissolved Al, As, B, Mo, Na, S, and V all significantly decreased after bioremediation. Increasing soil inoculant addition rate accelerated rates and extent of pH neutralization and element removal up to 0.1 wt %; further increases had little effect. Overall, glucose added at 1.8 wt % and soil inoculum added at 0.1 wt % provided the most effective minimal combination of carbon substrate and inoculum to drive pH neutralization and element removal.

Anaerobic digestion of activated sludge, anaerobic granular sludge and cow dung with food waste for enhanced methane production

The effect of inoculum [cow dung (CD), acclimatized anaerobic granular sludge (AAGS) and waste activated sludge (WAS)] on co-digestion of food waste (FW) was investigated in this study. Seven batch reactors were prepared using the different combinations of FW and inoculums and methane (CH4) generation was monitored for 30 d. Results suggested that inoculum type and combination cause significant effect on biomethanation process. The reactor with CD: AAGS: WAS: FW in 1:1:1:1 ratio showed the maximum CH4 generation (109 mL CH4 g−1 VS removed). There was reduction in volatile solids (VS) (16.24–56.58%) and soluble chemical oxygen demand (SCOD) (20.54–66.24%) during the AD process in all batch reactors. The results suggested that type and combination of inocula with FW was the prime factor in improving the co-digestion process. A combination of AAGS, CD and WAS with FW (1:1:1:1) appeared as the best co-digestion inocula for enhanced biomethanation process. Experimental results fits well with Gompertz and first order (FO) model for all waste combinations.

Temperature-mediated local adaptation alters the symbiotic function in arbuscular mycorrhiza.

Variation in the symbiotic function of arbuscular mycorrhizal fungi (AM fungi) has been demonstrated among distinct biotic and abiotic interactions. However, there is little knowledge on how local temperature conditions influence the functional divergence of AM symbionts in alpine ecosystems. Here, we conduct a reciprocal inoculation experiment to explore the three-way interactions among plants, AM fungal inoculum and temperature at sites of contrasting elevation. Evidence of local adaptation of plant growth was found only under low temperature conditions, with no consistent local versus foreign effect found in AM fungal performance. The origin of either the plant or the inoculum relative to the temperature was important in explaining symbiotic function. Specifically, when inoculum and temperature were sympatric but allopatric to the plant, poor adaptation by the plant to the novel environment was clearly found under both temperature conditions. Further analysis found that the symbiotic function was inversely related to fungal diversity under high temperature conditions. These results suggest that local adaptation represents a powerful factor in the establishment of novel combinations of plant, inoculum and temperature, and confirms the importance oftaking into account both biotic and abiotic interactions in the prediction of the response of symbionts to global environmental change.

Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico.

Understanding bacterial community dynamics as a result of an oil spill is important for predicting the fate of oil released to the environment and developing bioremediation strategies in the Gulf of Mexico. In this study, we aimed to elucidate the roles of temperature, water chemistry (nutrients), and initial bacterial community in selecting oil degraders through a series of incubation experiments. Surface (2 m) and bottom (1537 m) waters, collected near the Deepwater Horizon site, were amended with 200 ppm light Louisiana sweet crude oil and bacterial inoculums from surface or bottom water, and incubated at 4 or 24°C for 50 days. Bacterial community and residual oil were analyzed by pyrosequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that temperature played a key role in selecting oil-degrading bacteria. Incubation at 4°C favored the development of Cycloclasticus, Pseudoalteromonas, Sulfitobacter, and Reinekea, while 24°C incubations enhanced Oleibacter, Thalassobius, Phaeobacter, and Roseobacter. Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities. Pseudoalteromonas, Oleibacter, and Winogradskyella developed well in the nutrient-enriched bottom water, while Reinekea and Thalassobius were favored by low-nutrient surface water. We revealed that the combination of 4°C, crude oil and bottom inoculum was a key factor for the growth of Cycloclasticus, while the combination of surface inoculum and bottom water chemistry was important for the growth of Pseudoalteromonas. Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition for Oleibacter. Redundancy analysis further showed that temperature and initial community explained 57 and 19% of the variation observed, while oil and water chemistry contributed 14 and 10%, respectively. Overall, this study revealed the relative roles of temperature, water chemistry, and initial bacterial community in selecting oil degraders and regulating their evolution in the northern Gulf of Mexico.