Polysaccharide hydrolyzing enzyme activity of bacteria, native to Apis florea gut

Introduction and Aim: Apis florea commonly known as “dwarf honey bee” harbors enormous gut bacteria that can digest complex carbohydrates and other food components. In this regard, the present investigation was focused on analyzing the polysaccharide degrading ability of bacteria isolated from the gut of honeybee, for their possible application in nutraceutical and pharmaceutical industries. Materials and Methods: Nine bacterial isolates were screened for carbohydrate degrading enzymes viz., amylase, pectinase, cellulase, tannase and laccase, using respective substrate by plate assay method. Further activities of amylase and pectinase were measured quantitatively by dinitrosalicylic acid (DNS) method. Results: All the nine selected isolates exhibited amylase and pectinase activities. However, only two isolates exhibited lignolytic and cellulolytic activity. None of the isolates showed tannin degradation. Maximum amylase activity (4.95 U/mg) was observed in Bacillus halotolerans af-M9 followed by Klebsiella oxytoca af-G4 (4.62 U/mg). With respect to pectinase activity Klebsiella pneumoniae af-E17 displayed higher activity (0.24 U/mg) followed by Klebsiella oxytoca af-G4 (0.20 U/mg). Conclusion: Habitat-specific innovations are being explored for novel compounds for therapeutic applications. This study throws a light on selection of carbohydrate degrading bacteria from a new source i.e., GUT of honeybee.

Bacterial Degradation of Bacteriostatic Polyphenols, Tannins

Tannin degradation by bacteria has not been studied much as tannins are commonly known to be bacteriostatic due to enzyme inhibition, substrate deprivation, and the enzyme activity on the bacterial cell wall. However, about a handful of bacteria have been found to tolerate certain concentrations of tannin. This study focuses on isolating and identifying bacteria from decaying portions of tree bark for tannase production and effective catalysis of ester bond hydrolysis in tannins. Different concentrations of commercial tannic acid were used as the sole carbon source on mineral salt medium (MSM) agar plates, to test the maximum tolerable concentrations (MTCs) by the isolates. Tannin degradation was confirmed by a visual reading method and bacterial tannase activity and the biodegradation percentage were determined. One particular isolate was identified to have 50 g/L MTC of tannin, with a tannase activity of 51.61 U/mL that is optimum after 96 hours of incubation. The 16s rRNA sequencing results showed that the isolate belonged to Bacillus genus and the resulting bacterial strain isolate was found to be a new strain of Bacillus subtilis which was submitted to GenBank under the accession number MH330408.

APLIKASI FOSFAT PADA PROSES EKSTRAKSI TEH HIJAU UNTUK MINUMAN TEH HIJAU SIAP MINUM

Color is one of quality parameters that affects consumer intention to purchase ready to drink (RTD) green tea. Consumers expect RTD green tea to have yellow greenish color, however the color becomes brown and darker during the shelf life. This study aimed to evaluate the effect of phosphate mix addition to water prior to green tea leaves extraction on pH, color, and the tannin in tea extract, pre-RTD, and RTD during incubation period at 60°C for 2 days. The pre-RTD contained tea extract, sugar, and ascorbic acid. Addition of sodium bicarbonate was done in pre-RTD to obtain RTD with pH of 6.1±0.2. The type of phos-phate used was sodium acid pyrophosphate (SAPP) and phosphoric acid. The concentrations of SAPP were 650 and 1300 mg/L, while those of phosphoric acid were 125, 250, and 500 mg/L.The total phospho-rous added from the combination of SAPP and phosphoric acid was 221-521 mg/L. Meanwhile, green tea extracted without phosphate was used as a control. The results showed that phosphate addition to water prior to green tea extraction caused decrease in pH of tea extract from 5.83±0.18 to 2.8-3.8, decrease in browning intensity, and reduced tannin degradation during the incubation period. Sugar and ascorbic acid added to the tea extract resulted in pH in all samples <4.0 and maintained the lightness of the pre-RTD. Phosphate application was not able to retain the color of RTD after incubation period. This study showed that addition of phosphorous as a combination of SAPP and phosphoric acid to water at concentrations of 221-521 mg/L prior to green tea extraction had positive impact in reducing browning intensity of RTD green tea with pH of lower than 4.0.

Exploring the formaldehyde reactivity of tannins with different molecular weight distributions: bayberry tannins and larch tannins

In recent years, tannin degradation has been used to obtain tannin materials with an optimal molecular weight distribution (MWD) for synthesizing tannin-formaldehyde (TF) resin with high performance, but the optimal MWD of tannins is still unknown. The excellent formaldehyde reactivity of tannins is the basis for the synthesis of high-performance TF resin. Based on the formaldehyde reactivity of tannins, bayberry tannins and larch tannins were used to explore the optimal MWD of tannins for TF resin synthesis. Progressive solvent precipitation (PSP) was used to obtain tannin fractions with different MWDs. The formaldehyde reactivity of tannins was determined using the modified Stiansy method combined with the standard curve method (GB/T 17657-2013). The bayberry tannin fraction [weight-average molecular weight (Mw) of acetylated tannin: 4115, mean degree of polymerization (mDP): 6.64] and the larch tannin fraction (Mw of acetylated tannin: 3906, mDP: 5.84) had the best formaldehyde reactivity. Furthermore, significant differences in the formaldehyde reactivity of condensed tannins (CTs) with different MWDs were observed. The obtained results can be used to purposefully degrade tannins to achieve an optimal MWD, which is beneficial for the production of TF adhesives with high performance.

Integrated Approaches to Reveal Genes Crucial for Tannin Degradation in Aureobasidium melanogenum T9

Tannins biodegradation by a microorganism is one of the most efficient ways to produce bioproducts of high value. However, the mechanism of tannins biodegradation by yeast has been little explored. In this study, Aureobasidium melanogenum T9 isolated from red wine starter showed the ability for tannins degradation and had its highest biomass when the initial tannic acid concentration was 20 g/L. Furthermore, the genes involved in the tannin degradation process were analyzed. Genes tan A, tan B and tan C encoding three different tannases respectively were identified in the A. melanogenum T9. Among these genes, tan A and tan B can be induced by tannin acid simultaneously at both gene transcription and protein expression levels. Our assay result showed that the deletion of tanA and tanB resulted in tannase activity decline with 51.3 ± 4.1 and 64.1 ± 1.9 U/mL, respectively, which is much lower than that of A. melanogenum T9 with 91.3 ± 5.8 U/mL. In addition, another gene coding gallic acid decarboxylase (gad) was knocked out to better clarify its function. Mutant Δgad completely lost gallic acid decarboxylase activity and no pyrogallic acid was seen during the entire cultivation process, confirming that there was a sole gene encoding decarboxylase in the A. melanogenum T9. These results demonstrated that tanA, tanB and gad were crucial for tannin degradation and provided new insights for the mechanism of tannins biodegradation by yeast. This finding showed that A. melanogenum has potential in the production of tannase and metabolites, such as gall acid and pyrogallol.

Tannin Degradation by a Novel Tannase Enzyme Present in Some Lactobacillus plantarum Strains

ABSTRACTLactobacillus plantarumis frequently isolated from the fermentation of plant material where tannins are abundant.L. plantarumstrains possess tannase activity to degrade plant tannins. AnL. plantarumtannase (TanBLp, formerly called TanLp1) was previously identified and biochemically characterized. In this study, we report the identification and characterization of a novel tannase (TanALp). While all 29L. plantarumstrains analyzed in the study possess thetanBLpgene, the genetanALpwas present in only four strains. Upon methyl gallate exposure, the expression oftanBLpwas induced, whereastanALpexpression was not affected. TanALpshowed only 27% sequence identity to TanBLp, but the residues involved in tannase activity are conserved. Optimum activity for TanALpwas observed at 30°C and pH 6 in the presence of Ca2+ions. TanALpwas able to hydrolyze gallate and protocatechuate esters with a short aliphatic alcohol substituent. Moreover, TanALpwas able to fully hydrolyze complex gallotannins, such as tannic acid. The presence of the extracellular TanALptannase in someL. plantarumstrains provides them an advantage for the initial degradation of complex tannins present in plant environments.

Distribution of insoluble polysaccharides in the shoot apex of Rhododendron arboreum Linn. during the annual growth cycle

Starch grains occur all over the dormant shoot apex of <em>Rhododendron arboreum</em> except in the bud scales. They are abundant in the peripheral, rib and pith meristem cells. as well as in the youngest leaf primordia. Tannin is present in the entire dormant bud hut for the cells of the apical meristem and leaf primordia. Gradually, tannin degradation into numerous globules occurs. This is concomitant with the disappearance of starch grains and indicates the earliest structural manifestation of spring awakening by meristematic activity in the buds. The weak affinity of tannin globules to PAS is due to their hydrolysis which releases glucose for metabolic activities. Thus, a parallelism seems to exist between the metabolism of tannins and starch in relation to the various phases of bud development.