Retting and degumming of natural fibers by pectinolytic enzymes produced from Bacillus tequilensis SV11-UV37 using solid state fermentation.

The present study demonstrated the simultaneous production and optimization of pectinolytic enzymes (pectate lyase and polygalacturonase) under SSF from Bacillus tequilensis SV11-UV37 using wheat bran as a substrate, which is commercially viable and cost-effective. Optimization by one variable-at-a-time-approach showed a maximum yield of pectate lyase (1371.25 U/gds) and polygalacturonase (85.45 U/gds) with wheat bran using 80 % (v/w) moisture, 0.7 mm particle size, 20 % (v/w) inoculum, 1 % (w/w) pectin at 37 °C, pH 6 and 72 h of incubation. In addition, optimization using central composite design achieved 1.6-fold improvement in both pectate lyase (1828.13 U/gds) and polygalacturonase (105.55 U/gds) yield at optimum levels of pectin (3 %, w/w), inoculum size (20 %, v/w) and moisture level (80 %, v/w). Further, Retting studies concluded that the enzyme mixture was efficient in separating the whole fiber from kenaf and part (>75 %) from sunn hemp. In degumming of sunn hemp fibers, amount of galacturonic acid released and percentage weight loss was higher in successive alkali and enzymatic treatment than their independent treatments. The scanning electron microscopic analysis also confirmed that alkali followed by enzymatic treatment effectively removed non-cellulosic gummy material from the fiber; hence, this enzyme mixture may find feasible applications in the fiber and textile industry.

Streptosporangium terrae sp. nov., a novel actinomycete isolated from the rhizosphere of Callistemon citrinus (Curtis), India.

A novel actinomycete strain, designated VRC21(T), was isolated from the rhizosphere of Callistemon citrinus collected from Hyderabad, India. The morphological and chemotaxonomic properties of strain VRC21(T) was consistent with the characteristics of members of the genus Streptosporangium, that is, the formation of sporangia on aerial mycelium, coiled unbranched hyphae within the spore vesicle, the presence of meso-diaminopimelic acid in the cell wall, and madurose and galactose as major whole-cell sugars. Diagnostic polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol-mannosides. The predominant menaquinones were MK-9(H2) and MK-9(H4). The major cellular fatty acids were iso-C14:0, iso-C16:0, C17:0 10-methyl, C18:1w9c and C18:0 10-methyl. 16S rRNA gene sequence analyses revealed that strain VRC21(T) was a member of the genus Streptosporangium. The highest similarity values were observed with S. carneum DSM 44125(T) (98.2%) and S. fragile DSM 43847(T) (98.2%); the values of the remaining type strains were below 98%. The values of DNA-DNA relatedness between the strain VRC21(T) and the type strains of the related species were below 70%. On the basis of the polyphasic evidence, the strain VRC21(T) should be classified as novel species Streptosporangium terrae sp. nov. in the genus Streptosporangium. The type strain is VRC21(T) (=KCTC 29207(T)=MTCC 11724(T)).

A novel thermostable, alkaline pectate lyase from Bacillus tequilensis SV11 with potential in textile industry.

An extracellular pectate lyase was purified and characterized from a UV mutant of Bacillus tequilensis SV11. Purification resulted in a 16.2-fold improvement in the enzyme specific activity, with approximately 40.2% yield. SDS-PAGE showed that the enzyme had two subunits with molecular masses of 135 ± 2 and 43 ± 2 kDa. Further, MALDI-TOF MS experiments revealed that the mass spectrum of the second peptide significantly (91% score) matched with the unsaturated rhamnogalacturonyl hydrolase YteR OS-Bacillus subtilis (strain 168) by 27% sequence coverage, nominal mass 43,231 Da, and PI 5.91. The enzyme was optimally active at 60 °C, pH 9. Km and Vmax of the purified pectate lyase was found to be 1.220 mg/mL and 1773 U/mL, respectively. The enzyme was studied for its applicability in bioscouring and found to be efficient in the removal of 97.91% pectin of cotton fabric when compared with alkali-treated fabric.

Saccharopolyspora indica sp. nov., an actinomycete isolated from the rhizosphere of Callistemon citrinus (Curtis).

A novel actinomycete strain, designated VRC122T, was isolated from a Callistemon citrinus rhizosphere sample collected from New Delhi, India, and its taxonomic status was determined by using a polyphasic approach. Strain VRC122T was a Gram-stain-positive, aerobic, non-motile, non-acid-alcohol-fast strain. Phylogenetic analysis based on 16S rRNA gene sequences showed the strain was placed in a well-separated sub-branch within the genus Saccharopolyspora. The highest levels of 16S rRNA gene sequence similarity were found with Saccharopolyspora hirsuta subsp. kobensis JCM 9109T (98.71%), Saccharopolyspora antimicrobica I05-00074T (98.69%) and Saccharopolyspora jiangxiensis W12T (98.66%); 16S rRNA gene sequence similarities with type strains of all other species of the genus Saccharopolyspora were below 98%. Chemosystematic studies revealed that it contained meso-diaminopimelic acid. Arabinose and galactose were the predominant whole-cell sugars. Diagnostic polar lipids were diphosphatidylglycerol, phosphatidylinositol and phosphatidylcholine. MK-9(H6) was the predominant menaquinone. C14:0, C16:0, iso-C15:0, iso-C16:0, iso-C17:0, anteiso-C15:0, anteiso-C17:0, C17:0 cyclo and summed feature 3 (C16:1ω7c and/or C16:1ω6c) were the major cellular fatty acids. The G+C content of the genomic DNA was 69.5 mol%. The results of DNA-DNA hybridization (30%, 22% and 25%, respectively) with type strains of the above-mentioned species, in combination with differences in physiological and biochemical data supported that strain VRC122T represents a novel species of the genus Saccharopolyspora, for which the name Saccharopolyspora indica sp. nov., is proposed. The type strain is VRC122T (=KCTC 29208T=MTCC 11564T=MCC 2206T=ATCC BAA-2551T).

Nocardia bhagyanesis sp. nov., a novel actinomycete isolated from the rhizosphere of Callistemon citrinus (Curtis), India.

A novel actinomycete strain, designated VRC07(T), was isolated from a Callistemon citrinus rhizosphere sample collected from Hyderabad, India. Its taxonomic status was determined by using polyphasic approach. It is a Gram-positive, aerobic, non-motile, weakly acid-fast strain. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain VRC07(T) is a member of the genus Nocardia. The highest levels of 16S rRNA gene sequence similarity was found between the strains Nocardia niwae W9241(T) (99.6 %), Nocardia amikacinitolerans W9988(T) (99.3 %) and Nocardia arthritidis IFM 10035(T) (98.9 %); similarity to other type strains of the genus Nocardia was below 98.7 %. The organism had chemical and morphological features consistent with its classification in the genus Nocardia such as meso-diaminopimelic acid as the diagnostic diamino acid in the cell wall peptidoglycan. Arabinose and galactose as the diagnostic sugars. Diagnostic polar lipids were phosphatidylinositol, diphosphatidylglycerol, and phosphatidylglycerol. The predominant menaquinone was MK-8(H4, ω-cycl). The major fatty acids were C16:0, C18:0, C18:1 w9c, C18:0 10-methyl TBSA and sum in feature 3 (16:1 w7c/16:1 w6c). The G+C content of the genomic DNA was 68.5 mol%. The DNA-DNA relatedness data, together with phenotypic differences clearly distinguished the isolate from its closest relatives. On the basis of these phenotypic and genotypic data, the isolate represents a novel species, for which the name Nocardia bhagyanesis sp. nov., is proposed. The type strain is VRC07(T) (=KCTC 29209(T) = MTCC 11725(T) = ATCC BAA-2548).

Evaluation of pretreatment methods for enzymatic saccharification of wheat straw for bioethanol production.

Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. The current study is focused on two different pretreatment methods of wheat straw using mild temperatures (100°C for 2h and RT for overnight). In one method, native substrate was treated with 1.5% (w/v) NaOH at two different above mentioned conditions followed by acid hydrolysis (0.75% (v/v) sulfuric acid at 100°C for 2h). In another method, the native substrate was initially treated with acid (0.75% (v/v) sulfuric acid at 100°C for 2h) followed by treatment with 1.5% (w/v) NaOH at two different above conditions. After the pretreatments, the residues were treated with Accellerase 1500 (26U/g) and maximum yield of glucose (65.2gL(-1)) were found with 0.75% sulfuric acid (100°C for 2h) followed by alkali (1.5% NaOH at 100°C for 2h). Fermentation of this hydrolyzate using Saccharomyces cerevisiae strain produced 24.4gL(-1) of ethanol with corresponding yield of 0.44g/g.