Fermentation Tests Research Articles

Novel Streptomyces Sp. Reported in 2018: A Meta-Analysis

Streptomyces species are very well known for the production of antimicrobials and enzymes. The objective of this review was to search for the novel Streptomyces isolated in 2018 along with their characteristics and possible antimicrobial properties. The literature search was done according to the PRISMA flow diagram, where 28 research papers were eligible for the review. Data entry and analyses were performed using IBM SPSS Statistics version 25, while the phylogenetic tree was constructed using Geneious Prime Software. The data on general characteristics, biochemical as well as sugar fermentation tests, 16S rRNA gene sequence similarity and DNA-DNA hybridization relatedness were extracted from the research papers and summarized in tables and figures. The biosynthesis gene cluster (BGC) was identified using ‘antibiotics and secondary metabolite analysis shell-antiSMASH’, which showed the possibility of production of new antibiotics, antifungal and antitumor substances from the 28 novel Streptomyces isolated in 2018 which would contribute to the global effort to fight against growing multidrug-resistance.

Insights into the Anaerobic Hydrolysis Process for Extracting Embedded EPS and Metals from Activated Sludge.

The amount of sewage sludge generated from wastewater treatment plants globally is unavoidably increasing. In recent years, significant attention has been paid to the biorefinery concept based on the conversion of waste streams to high-value products, material, and energy by microorganisms. However, one of the most significant challenges in the field is the possibility of controlling the microorganisms’ pathways in the anaerobic environment. This study investigated two different anaerobic fermentation tests carried out with real waste activated sludge at high organic loading rate (10 g COD L−1d−1) and short hydraulic retention time (HRT) to comprehensively understand whether this configuration enhances extracellular polymeric substance (EPS) and metal solubilisation. The quantity of EPS recovered increased over time, while the chemical oxygen demand to EPS ratio remained in the range 1.31–1.45. Slightly acidic conditions and sludge floc disintegration promoted EPS matrix disruption and release, combined with the solubilisation of organically bound toxic metals, such as As, Be, Cu, Ni, V, and Zn, thereby increasing the overall metal removal efficiency due to the action of hydrolytic microorganisms. Bacteroidetes, Firmicutes, and Chloroflexi were the most abundant phyla observed, indicating that the short HRT imposed on the systems favoured the hydrolytic and acidogenic activity of these taxa.

644. Phenotypic and Genomic Analysis of Novel, Fastidious, Gram-negative Bacilli Isolated from Clinical Wound Specimens

BackgroundAnimal bites are considered the thirteenth leading cause of nonfatal ED visits. Epidemiology studies have shown a rise in dog bites during the COVID-19 pandemic in the U.S. In Oct. 2020, we received a facultatively anaerobic, non-hemolytic Gram-negative rod (OL1) from a dog bite wound for identification. 16S rRNA gene sequencing showed OL1 was 95.9% identical to Ottowia pentelensis in the family Comamonadaceae. Our historical sequence database revealed 8 additional isolates (OL2-OL9) from hand wounds/abscesses (including 3 dog bites) since 2012 that had ⩾ 99.8% identity with OL1. Most other Ottowia sp. have been isolated from industrial and food sources, with no reports from patient samples. As these clinical isolates likely represent a novel Ottowia species, we aimed to characterize them using both phenotypic and genomic approaches.MethodsThe OL isolates were tested in API 20 NE panels (8 conventional and 12 assimilation tests) for 4 d. Paired-end genomic DNA libraries (Nextera DNA Flex Library Prep, Illumina) were sequenced as 150 nt reads by Illumina NovaSeq. De novo assembly, annotation, functional prediction, and phylogenetic analyses were performed with Geneious, PATRIC, and web-prediction databases. Strain comparison was done with StrainTypeMer.ResultsAll 9 OL isolates were negative for indole, urea, arginine, esculin, PNPG, glucose fermentation and carbohydrate assimilation tests. Potassium gluconate assimilation and gelatin hydrolysis were positive for 5 and 4 isolates, respectively. StrainTypeMer showed the isolates from different patients were not closely related, but 2 from the same patient were indistinguishable. The estimated genome size was ~3.1 Mbp, with 66.1% G/C, and ~3523 coding genes. Potential virulence factors (BrkB and MviM), multidrug efflux systems (MdtABC-TolC and Bcr/CflA), and 1-2 intact prophages were identified. Genomic phylogenetic analysis with RAxML showed the OL isolates clustered separately from all known Ottowia spp.ConclusionThese OL isolates are fastidious, Gram-negative bacilli from clinical wound specimens, and are associated with dog bites. Genomic and 16S rRNA gene sequence analysis suggests these isolates constitute a novel species within the family Comamonadaceae.Disclosures All Authors: No reported disclosures

Controlled fermentation of food industrial wastes to develop a bioorganic fertilizer by using experimental design methodology

A controlled fermentation was conducted to develop and design a bioorganic fertilizer based on three wastes generated by the food industry: olive mill wastewater (OMW), molasses and rice hulls by inoculation with selected strains of lactic acid bacteria (LAB), of the species “ Lactiplantibacillus plantarum” and “ Levilactobacillus brevis ” and of the yeast of the species “ candida famata ”. The fermentation with commercial yeasts and particularly the species of “ saccharomyces ” produced an unstable fertilizer with a high pH value (6.14).Whereas, the fermentation test with an inoculum composed of 20% yeast and 80% lactic acid bacteria showed a decrease in pH at 4.66 and a maximum enzymatic activity of 43.900 IU/l after 30 h. This combination allowed an appropriate morphological and microbiological quality of the bioorganic fertilizer. To determine with precision, the optimum conditions of this fermentation an optimization design was applied. As a result of experiments and statistical validation of the fitted model, the bioorganic fertilizer with the lowest pH value was achieved after fermentation of 53.2% OMW, 19.1% molasses, 21.3% rice hulls and 6.4% inoculum content. The final pH was able to reach a value of 4.07 with desirability of the order of 99.7%. A fertilizer with the lowest possible pH allowed farmers longer storage periods and required no special storage conditions.

Near-infrared calibration models for estimating volatile fatty acids and methane production from in vitro rumen fermentation of different total mixed rations

Volatile fatty acids (VFA) and methane (CH4) are the major products of rumen fermentation. The VFA are considered an energy source for the animal and rumen microbiota, and CH4 (which is released by eructation) is considered an energy loss. Quantification of these fermentation products is fundamental for the evaluation of feeds and diets, and provides important information regarding the use of nutrients by ruminants. Near-infrared (NIR) spectroscopy is increasingly used for the evaluation of animal feeds because it is rapid, nondestructive, noninvasive, and inexpensive; does not require reagents; and the results are reproducible. The aim of this study was to develop NIR calibration models for estimating the production of VFA (acetic, propionic, butyric, valeric, isovaleric, and isobutyric acids), total gas, and CH4 using in vitro gas production tests with buffered rumen inoculum throughout fermentation. Fifty-four total mixed rations (TMRs) were examined, and rumen fluid was manually collected from 2 dry Holstein dairy cows that had ruminal fistulas and were fed at maintenance energy levels. Then, 30 mL of buffered rumen fluid was incubated in bottles with ~220 mg of TMR. The total gas, VFA, and CH4 were measured after 2, 5, 9, 24, 30, 48, and 72 h of rumen incubation for each TMR. The VFA were measured on 32 randomly selected TMR. In particular, 7 bottles were used for each TMR, one for each incubation time. Methane was measured in the headspace and VFA were measured in the buffered rumen fluid. The bottles were considered experimental units for calibration purposes. The production of CH4 was quantified from the bottle headspaces by gas chromatography, and total gas production was measured using a pressure transducer at each incubation time. Two aliquots of the fermented liquids were sampled by opening the bottles at each incubation time, and (1) the concentrations of VFA were determined by gas chromatography or (2) spectra were obtained from Fourier-transform NIR spectroscopy. The data were randomly divided into calibration and validation data sets. The average concentrations of acetic acid (45.30 ± 11.92 and 43.86 ± 11.93 mmol/L), propionic acid (14.97 ± 6.08 and 14.38 ± 6.56 mmol/L), butyric acid (8.47 ± 3.47 and 8.65 ± 3.79 mmol/L), total gas (111.34 ± 81.90 and 116.46 ± 82.44 mL/g of organic matter), and CH4 (9.65 ± 9.45 and 10.35 ± 9.33 mmol/L) were similar in the 2 data sets. The best calibration models were retained based on the coefficient of determination (R2) and the ratio of prediction to deviation (RPD). The R2 values for prediction of VFA ranged from 0.69 (RPD = 3.28) for valeric acid to 0.94 (RPD = 4.20) for acetic acid. The models also provided good predictions of CH4 (R2 = 0.89, RPD = 3.05) and cumulative gas production (R2 = 0.91, RPD = 3.30). The models described here precisely and accurately estimated the production of CH4 and VFA during in vitro rumen fermentation tests. Validations at additional laboratories may provide more robust calibrations.

A comparative study for production of germ tube in Candida albicans of various pulmonary samples, by different methods in a tertiary care hospital of south west Rajasthan

Background: Systemic candidiasis is associated with a high crude mortality rate, even with first line antifungal therapy. C. albicans is the predominant cause of invasive fungal diseases which is a serious public health issue. The main objective was to assess the reliability of different media for germ tube production in Candida albicans isolated from various clinically diagnosed pulmonary samples.Methods: All Candida isolates were identified and speciated by conventional methods such as Gram’s staining, germ tube test, chlamydospore formation on corn meal agar, sugar fermentation test, sugar assimilation test, and growth on Hi-chrome candida agar.Results: Out of 108 clinical isolates of Candida albicans, 5 different methods were used for germ tube production. Pooled human sera showed 93/108 (86.1%) was the most sensitive method wherein YEPD (yeast extract peptone dextrose) broth 91/108 (84.7%) was the reliable and easy method for detection of germ tube, followed by trypticase soy broth 81/108 (81.4%); peptone water 80/108 (74.7%) and 2% sucrose 71/108 (65.7%).Conclusions: YPED broth is found to be a better serum free substrate and subsequently for the presumptive differentiation of C. albicans from non-albicans candida (NAC), without the extensive time required for the preparation and testing of pooled human serum. Furthermore, this medium is commercially available, more stable, effective, and is not bio hazardous.

Aquafeed Production from Fermented Fish Waste and Lemon Peel

In order to obtain a high-protein-content supplement for aquaculture feeds, rich in healthy microorganisms, in this study, Saccharomyces cerevisiae American Type Culture Collection (ATCC) 4126 and Lactobacillus reuteri ATCC 53608 strains were used as starters for fermenting fish waste supplemented with lemon peel as a prebiotic source and filler. Fermentation tests were carried out for 120 h until no further growth of the selected microorganisms was observed and the pH value became stable. All the samples were tested for proteins, crude lipids, and ash determination, and submitted for fatty acid analysis. Moreover, microbiological analyses for coliform bacteria identification were carried out. At the end of the fermentation period, the substrate reached a concentration in protein and in crude lipids of 48.55 ± 1.15% and 15.25 ± 0.80%, respectively, representing adequate levels for the resulting aquafeed, whereas the ash percentage was 0.66 ± 0.03. The main fatty acids detected were palmitic, oleic, and linoleic acids. Saturated fatty acids concentration was not affected by the fermentation process, whereas monounsaturated and polyunsaturated ones showed an opposite trend, increasing and decreasing, respectively, during the process. Coliform bacteria were not detected in the media at the end of the fermentation, whereas the amount of S. cerevisiae and L. reuteri were around 1011 and 1012 cells per g, respectively.

Speciation of candida species isolated in clinical samples in a tertiary health care centre in Northern India

The purpose of this study is to isolate, identify and specification of various the Candida species from various clinical samples in a tertiary care hospital, and to characterize various the isolated Candida species. A study was conducted on people of different age groups from January 2019 to December 2019. Candida species isolated from different patients by using Potassium Hydroxide mount and processed by BacTalert 3D (Biomerieux) automated blood culture system. Further culture identification of Candida species were done on Sabouraud dextrose agar (SDA). Speciation of Candida was done using Germ tube test, CHROM agar Candida Medium, Cornmeal agar, Sugar Fermentation test and Sugar Assimilation test.In our study was the most common species isolated, among non albicans Candida i.e. 21 (38.9%); 19(35.2%) of was the most common followed by 9(16.7%) ofand 5(9.3%) of . Maximum number of Candida isolates were obtained from NICU i.e. 27(50.0%) followed by 11 from Med (20.3%), 7 from E/W (13.0%), 2 from BICU (3.7%), 2 from Skin (3.7%), 1 from PICU (1.9%), and 1 from R/R (1.9%).Our study showed that is the most common isolates species. Among , was found to be the most common isolate followed by . Children less than 1 year are most affected with maximum number of Candida species were obtained from NICU department. HiChrom Candida is proven to be more useful as differential agar.

Semi-continuous fermentation of chopped rice straw in a solid-state anaerobic digester: Influences of the tank height-to-diameter ratio, solid-state bed concentration, and leachate recirculation ratio

Chopped rice straw fermentation in solid-state anaerobic digesters (SS-ADs) is a viable path for biogas generation. Thus, three fermentation test series in typical anaerobic digesters were operated to investigate the effects of the external surface area, permeability, and liquid fluidity of the solid-state bed (SSB) in improving anaerobic digestion, as determined by varying the tank height-to-diameter (H:D) ratio, SSB concentration, and leachate recirculation ratio (RR), respectively. In Series A, the H:D ratio impacted the modulation of digestion progress, including biogas generation, volatile fatty acids release, and lignocellulosic degradation. In Series B, the use of an SSB concentration below the inflection threshold (10.7 %–13.3%) for biogas production decline resulted in the highest methane yield and average methane content. In Series C, a 25.0% RR increased methane production significantly (P < 0.01) in both the semi-continuous fermentation SS-AD and downward plug-flow anaerobic digester (DPAD). Accordingly, energy flow analysis revealed that the DPAD produced 19.3% more net energy than the liquid anaerobic digester.

Isolation, identification and biochemical characterization of lactic acid bacteria from selected yogurt samples

This research was conducted to study the types of lactic acid bacteria (LAB) present in selected yogurts available in the local market of Bangladesh. For this purpose, nine different yogurt samples were collected (viz. MV, Mw, Pst, Psr, Bik, Bog, WF, Kw and Nab) and cultured in the selective MRS agar media for enumerating LAB colony. Out of 9 samples, colony forming LAB were found in 6 samples and the population ranged from 1.0×104 to 9.5×105 cfu/ml. Catalase negative and Gram’s positive colonies were initially identified as LAB. Then the isolates were purified by subsequent culturing in MRS broth and MRS agar media. Biochemical properties of selected colonies were evaluated by performing gas production from glucose, growth at different temperatures (10ºC, 15ºC and 45ºC), growth at different NaCl concentrations (2, 4 and 6.5% NaCl) and sugar fermentation tests (lactose, sorbitol, salicin, trehalose, melibiose, sucrose, mannitol, melezitose, maltose, galactose, glucose, arabinose, raffinose and ribose). According to the tests stated above, a total of five different species of LAB were identified from 6 samples. The isolate Lactobacillus lactis was identified in MV, PSr and Bog yogurt, while Lactobacillus bulgaricus was found in MV and Bik yogurt. The species Leuconostoc cremoris, a avor producing bacteria, was found in six yogurt samples. On the other hand, Lactobacillus acidophilus and Lactobacillus helveticus was found only in Pst and Psr samples, respectively. Bang. J. Livs. Res. Vol. 27 (1&amp;2), 2020: P. 64-72

Effect of dietary inclusion of tea residue and tea leaves on ruminal fermentation characteristics and methane production

The aim of this study was to compare the differences of dietary tea leaves (TL) and tea residue (TR) inclusion on rumen fermentation characteristics and to explore whether TR could be an alternative feedstuff of ruminants. For these purposes, seven treatments consisted of two inclusion types (TL vs. TR) and three inclusion levels (g/g of dry matter basis) of 10% (TL10/TR10), 20% (TL20/TR20), and 30% (TL30/TR30) in each inclusion type, plus control group with inclusion of 0% (CON) were designed, with four replicates in each group, to conduct an in vitro ruminal fermentation test. Results showed that the contents of crude protein, neutral detergent fiber, and acid detergent fiber were higher in TR than TL, while TL contained more ether extract and crude ash than TR. Interaction effects between inclusion type and inclusion level were observed in concentrations of isobutyrate and microbial crude protein (MCP), as well as in gas production and digestibility of organic matter. Fermentation characteristics were significantly influenced by TL and TR depending on the inclusion level, except for the concentration of total branched-chain volatile fatty acid. These significant differences of fermentation characteristics due to inclusion level mainly focused on CON and tea inclusion, with higher values in CON than TR or TL groups. The total gas production during the 48-h incubation showed no differences among CON, TL10, and TR10. The inclusion of TR and TL decreased the production of methane. The concentration of MCP in CON, TR10 and TR30 was lower than TR20 and all TL groups. In conclusion, dietary inclusion of TR and TL possessed equivalent effect on rumen fermentation characteristics and methane production, substituting diet with TR or TL for over 10% would inhibit rumen fermentation despite positive effects in TR20 and all TL groups regarding more MCP and less methane production. This study indicates that special attention should be paid to the inclusion level of TR and TL when considering them as alternative feedstuffs of ruminants. Further in vivo study is needed to evaluate the applicability of tea residue as a feedstuff for production of ruminants.

Preliminary study for investigation of G. anatis in broilers Abdelazeem M. Algammal1, Wafaa A. Abd El-Ghany2, Amira A. Elewa3, and Ahmed M. Hamouda3

Gallibacterium anatis is recognized as a globally distributed species of bacteria that has been isolated from birds . The aim of the present prelaminary study is to investigate the prevalence of G. anatis isolated from diseased chickens from private commercial broiler farms at Ismailia governorate, Egypt. A total of 80 tracheal swabs obtained from broiler chickens suffering from respiratory manifestations. The collected specimens were subjected to bacteriological examination and the prevalence of G.anatis was 35%. All obtained isolates were positive for oxidase, catalase, nitrate reduction, sucrose, sorbitol, and mannitol fermentation tests. However, the obtained isolates were negative for citrate utilization, indole, urease, gelatinase and maltose fermentation tests. Besides, the recovered isolates were negative for the motility test. The gold standard method of bacterial isolation and identification( including culture characters, hemolytic activity on blood agar, morphological characters, motility test, and biochemical characteristics) is essential for characterization of G. anatis in birds.

Identifikasi bakteri patogen Aeromonas sp. pada ikan Nila (Oreochromis niloticus) di Desa Matungkas, Kecamatan Dimembe, Kabupaten Minahasa Utara

The purpose of this study was to identify the bacteria Aeromonas sp. in a tilapia (Oreochromis niloticus) culture pond in Matungkas Village, Dimembe District, North Minahasa Regency. Bacterial identification was carried out at the Laboratory of the Fish Quarantine Center for Quality and Safety Control of Fishery Products, Manado. The time of the study was carried out from February 2021 - June 2021. Ten samples of fish were selected from 3 existing ponds for this study with the criteria of fish that have clinical signs of disease infection such as pale body surface, red spots and ulcers. From 10 samples, 19 isolates were obtained to be identified. The bacterial method was carried out based on the results of gram tests and biochemical tests which included: Gram Tests, Motility Test, Oxidase Test, Oxidative Fermentative Test, Tolerance Test to incubation temperature, Tolerance Test to pH of the media, Tolerance Test to the concentration of NaCl in the media and rimler – shotts selective media test. Of the 19 isolates from 10 samples identified, there were 7 isolates that were positive for A. hydrophila, namely: N1.4.1, N2.1.1, N2.1.2, N2.2.1, N2.3.2, N3.3.1, and N3.3.2. Twelve other isolates were negative for A. hydrophila. The characters of A. hydrophila identified are creamy in colour, gram negative, oxidase positive, bacteria tolerance to temperature 4 °C positive, 37 °C positive, 50 °C negative, can move (motile), fermentative, pH tolerance test media pH 3 negative, pH 5 positive, pH 9 positive, pH 11 positive, tolerance test for NaCl concentration 0.5% positive, 3% positive, 5% negative, rimler – shotts positive. All sampling sites (ponds) in Matungkas Village were infected with bacteria.

Characterization and pathogenicity of symbiotic bacteria associated with entomopathogenic nematode: Steinernema species KALRO

The soil inhibiting entomopathogenic nematodes (EPNs), in the family Steinernematidae and Heterorhabditidae, are useful insect biological control agents. They have been used in the management of economically important crop pests. The EPNs are mutually associated with symbiotic bacteria genus Xenorhabdus and Photoharbdus respectively. The study aimed to isolate, characterize and evaluate the pathogenicity of symbiotic bacteria associated with EPN Steinernema sp. Kalro (Accession MW151701). The EPN Steinernema sp. Karlo was multiplied using the insect baiting technique. Its bacteria symbiont was isolated and characterized based on microscopic, biochemical, and physiological features like Gram staining, urease, motility test, and glucose fermentation test). Molecular identification and phylogenetic analysis were performed on 16S rDNA nucleotide sequence. Pathogenicity of the bacteria isolate was evaluated against Tuta absoluta larvae with mortality data recorded after 24 and 48hours of exposure to the bacterial cell suspension. The bacteria were found to be motile and glucose fermentation positive. Sequence analysis of 16S rDNA region resulted in 1500bp sequence with maximum similarity of between 97 and 98.93%, with Xenorhabdus spp Accessions from Genbank. It closely matched to Xenorhabdus sp. My8NJ with 98.93% similarity (Accession AB507811.1). Mean percent larval mortality of 68±4.9 and 88±8.0 in the lowest cell suspension was observed in 24 and 48h of exposure. It’s concluded that, the symbiotic bacteria associated with Steinernema sp. Kalro is Xenorhabdus sp. strain Kalro Genbank Accession MW245845. The bacteria is a potential biological control agent against Tuta absoluta larvae. Further classification of the bacteria to species level and pathogenicity trials in the screen house and field are recommended.

Effect of Lactic Acid Bacteria on the Pharmacokinetics and Metabolism of Ginsenosides in Mice.

This study aims to investigate the effect of lactic acid bacteria (LAB) on in vitro and in vivo metabolism and the pharmacokinetics of ginsenosides in mice. When the in vitro fermentation test of RGE with LAB was carried out, protopanaxadiol (PPD) and protopanaxadiol (PPD), which are final metabolites of ginsenosides but not contained in RGE, were greatly increased. Compound K (CK), ginsenoside Rh1 (GRh1), and GRg3 also increased by about 30%. Other ginsenosides with a sugar number of more than 2 showed a gradual decrease by fermentation with LAB for 7 days, suggesting the involvement of LAB in the deglycosylation of ginsenosides. Incubation of single ginsenoside with LAB produced GRg3, CK, and PPD with the highest formation rate and GRd, GRh2, and GF with the lower rate among PPD-type ginsenosides. Among PPT-type ginsenosides, GRh1 and PPT had the highest formation rate. The amoxicillin pretreatment (20 mg/kg/day, twice a day for 3 days) resulted in a significant decrease in the fecal recovery of CK, PPD, and PPT through the blockade of deglycosylation of ginsenosides after single oral administrations of RGE (2 g/kg) in mice. The plasma concentrations of CK, PPD, and PPT were not detectable without change in GRb1, GRb2, and GRc in this group. LAB supplementation (1 billion CFU/2 g/kg/day for 1 week) after the amoxicillin treatment in mice restored the ginsenoside metabolism and the plasma concentrations of ginsenosides to the control level. In conclusion, the alterations in the gut microbiota environment could change the ginsenoside metabolism and plasma concentrations of ginsenosides. Therefore, the supplementation of LAB with oral administrations of RGE would help increase plasma concentrations of deglycosylated ginsenosides such as CK, PPD, and PPT.

Pretreatment of Corn Stover Using an Extremely Low-Liquid Ammonia (ELLA) Method for the Effective Utilization of Sugars in Simultaneous Saccharification and Fermentation (SSF) of Ethanol

Extremely low-liquid ammonia (ELLA) pretreatment using aqueous ammonia was investigated in order to enhance the enzymatic saccharification of corn stover and subsequent ethanol production. In this study, corn stover was treated with an aqueous ammonia solution at different ammonia loading rates (0.1, 0.2, and 0.3 g NH3/g biomass) and various liquid-to-solid (L/S) ratios (0.55, 1.12, and 2.5). The ELLA pretreatment was conducted at elevated temperatures (90–150 °C) for an extended period (24–120 h). Thereafter, the pretreated material was saccharified by enzyme digestion and subjected to simultaneous saccharification and fermentation (SSF) tests. The effects of key parameters on both glucan digestibility and xylan digestibility were analyzed using analysis of variance (ANOVA). Under optimal pretreatment conditions (L/S = 2.5, 0.1 g-NH3/g-biomass, 150 °C), 81.2% glucan digestibility and 61.1% xylan digestibility were achieved. The highest ethanol yield achieved on the SSF tests was 85.4%. The ethanol concentration was 14.5 g/L at 96 h (pretreatment conditions: liquid-to-solid ratio (L/S) = 2.5, 0.1 g-NH3/g-biomass, 150 °C, 24 h. SSF conditions: microorganism Saccharomyces cerevisiae (D5A), 15 FPU/g-glucan, CTech2, 3% w/v glucan, 37 °C, 150 rpm).

Influence of volatile solids and pH for the production of volatile fatty acids: Batch fermentation tests using sewage sludge

The aim of this work was to study the effect of volatile suspended solid (VSS) and pH on volatile fatty acids (VFA) production from waste activated sludge (WAS) fermentation by means of batch tests. The final goal was to gain insights to enhance VFA stream quality, with the novelty of using WAS with high sludge retention time. Results revealed that the optimum conditions to maximize VFAs and minimize nutrients and non-VFA sCOD are a VSS concentration of 5.9 g/L and initial pH adjustment to pH 10. The WAS bacterial community structures were analysed according to Next Generation Sequencing (NGS) of 16S rDNA amplicons. The results revealed changes of bacterial phyla abundance in comparison with the batch test starting condition.

KARAKTERISASI ISOLAT BAKTERI PENGHASIL SELULOSA DARI BUAH NAGA MERAH (Hylocereus polyrhizus)

Cellulose is a natural polymer widely used for general industrial purposes. The development of science utilizes bacteria from certain fruits to produce biosellulose. Red dragon fruit ( Hylocereus polyrhizus ) contains a lot of sugar which can be bioconverted to cellulose by cellulose- producing lines. The research aimed to obtain bacteria from red dragon fruit with the potential to produce cellulose, then conduct morphological and biochemical characterization. The research was conducted by the isolation of bacteria from the fruit, purification, and screening tests using Hestrin-Schramm medium. The isolates obtained were characterized morphologically through macroscopic and microscopic observation and the biochemically through catalase test, carbohydrate fermentation, starch and gelatin hydrolysis, motility, and IMViC (Indole, Methyl red, Voges- Proskauer, Citrate). The results showed that 4 bacterial isolates had the potential to produce cellulose. Based on Bergey's Manual of Systematic Bacteriology, 3 bacterial genera were obtained, namely Acetobacter, Gluconacetobacter, and Azotobacter. The results of the characteristics of the isolates obtained at IBBN 2-2 were positive in the catalase test, sucrose and lactose fermentation, and methyl red. IBBN 3-1 was positive in the catalase test, sugar fermentation, starch hydrolysis, methyl red, and citrate. IBBN 3-2 was positive in the sucrose and glucose fermentation test, gelatin hydrolysis and 4-1 IBBN was positive in the sucrose fermentation test and gelatin hydrolysis.

ISOLATION AND CHARACTERIZATION OF IAA-PRODUCING RIZOSPHERE BACTERIA FROM RICE PLANTS (ORYZA SATIVA L.) IN KEDUNGPANI URBAN VILLAGE, SEMARANG CITY

Rhizosphere bacteria live in the soil around plant roots. Various rhizosphere bacteria are able to produce the hormone Indole-3-Acetic Acid (IAA) which stimulates plant growth. This study aims to isolate and characterize IAA-producing rhizosphere bacteria in rice plants in the rice fields of Kedungpani urban village, Semarang city. Bacterial enumeration was carried out using the total plate count (TPC) method. The isolates obtained were characterized by observation of colony and cell morphology, gram staining, endospore staining, catalase test, and sugar fermentation test. The ability to produce the IAA hormone was tested using Salkowski's reagent. The enumeration results showed that the total bacteria in the sample was 2.9 x 105 CFU / g. A total of 10 isolates were obtained and were able to produce the IAA hormone with various concentrations. Isolates KP1, KP2, KP3, KP4, KP5, KP6, KP9, KP13, KP14, and KP15 produced IAA with concentrations of 3.389, 5.111, 3.000, 1.667, 1.944, 5.056, 5.444, 4.500, 5.056, and 10.833 ppm, respectively. The results showed that there were 5 isolates with the highest IAA concentrations, namely KP2, KP6, KP9, KP14, and KP15 which had the potential to be used as biostimulant agents for plants.

Isolation and Identification of Lactic Acid Bacteria from Cow Milk and Milk Products.

Lactic acid bacteria (LAB) have long been consumed by people in several fermented foods such as dairy products. A study was conducted on lactating dairy cows to isolate and characterize LAB from dairy products found in and around Bahir-Dar city, North Western Ethiopia. Milk and milk products were randomly collected from dairy farms, milk vending shops, individual households, and supermarkets for bacteriological investigations. A total of sixteen samples were taken from different sources and cultured on different selective media: de Man, Rogosa, and Sharpe (MRS) agar for Lactobacillus spp.; M17 agar for Lactococcus spp.; Rogasa SL agar for Streptococci spp.; and MRS supplemented with cysteine (0.5%) for Bifidobacteria spp. Different laboratory techniques were implemented for LAB isolation and identification. A total of 41 bacterial isolates were grouped under five different genera of LAB and Bifidobacteria spp. were identified based on the growth morphology on the selective media, growth at a different temperature, gas production from glucose, carbohydrate fermentation, and other biochemical tests. LAB genera such as Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, Streptococcus, and Bifidobacterium spp. were isolated and identified from raw milk, cheese, and yogurt. Based on the current study, the majority of the LAB (24.38%) was isolated from cheese and yogurt. Among these, Lactobacillus, Lactococcus (21.94%), Streptococcus (19.51%), Leuconostoc (14.64%), Bifidobacteria (12.19%), and Pediococcus (7.31%) spp. were also identified from these products. Furthermore, based on the bacterial load count and different identification methodologies, our study revealed that Lactobacillus spp. were the dominant LAB isolated from milk and milk products. As a result, since there are few studies on the isolation and identification of lactic acid bacteria from dairy products in Ethiopia, more research studies are needed to complete the identification and characterization to species level and their possible role as probiotics.