Assessment of bacterial diversity in agricultural by-product compost by sequencing of cultivated isolates and amplified rDNA restriction analysis

An investigation of bacterial diversity in compost was performed using molecular chronometer in order to reveal its phylogeny. Thirty-three bacterial isolates isolated from compost were analyzed by 16S rRNA gene sequencing which revealed phylogenetic lineage of class Bacilli, γ, β-Proteobacteria, and Actinobacteria. Among these lineages, isolates belonging to class Bacilli consisted of species from genera Staphylococcus, Bacillus, Terribacillus, and Lysinibacillus. From phylum Actinobacteria: Microbacterium barkeri and Kocuria sp. were identified. Other bacterial groups had phylogenetic linkage with genera Comamonas and Acidovorax (class β-Proteobacteria); Serratia, Klebsiella, and Enterobacter (class γ-Proteobacteria). Similar isolates were analyzed through ARDRA. Amplified product of 16S rRNA gene from each isolates was subjected to cleavage by enzymes HpaII, HinfI, and MspI in separate reaction tubes. HpaII generated 2–6 bands ranging from 90–688 bp, HinfI generated 2–5 bands of 71–1,038 bp, and MspI 2–7 bands of 69–793 bp. The restriction patterns from HpaII, HinfI, and MspI were normalized separately and combined by means of pattern recognition software “Diversity Database.” HpaII had highest discrimination index (0.72) than HinfI (0.68) and MspI (0.65), and the combination of all three showed discrimination index (0.69). Numerical analysis of ARDRA patterns demonstrated sufficient phylogenetic information for characterizing bacterial diversity. Phylogenetic relationship obtained among isolates through ARDRA was compared with 16S rRNA gene sequence and ARDRA results showed sufficiently similar 16S rRNA gene sequence analysis, but not an overlapping. It has been observed that ARDRA technique facilitates the identification of bacteria in less than 36 h as compared to traditional 16S rRNA gene sequencing.     

A hypercellulolytic mutant of Fusarium oxysporum

Multiple mutagenesis of Fusarium oxysporum DSM 841 resulted in enhanced yields of cellulases. The hypercellulolytic mutant (NTG-19) secretes high levels of extracellular cellulases on different cellulosic substrates. Addition of surfactant, Tween-80, further increased enzyme secretion by about 30%. The results on hydrolysis of wheat straw by parent strain, DSM 841 and mutant NTG-19 cellulases also revealed a significant improvement in the hydrolytic potential of the cellulolytic enzymes from the mutant NTG-19.     

In Situ Bioremediation Potential of an Oily Sludge-Degrading Bacterial Consortium

A field-scale study was conducted in a 4000 m² plot of land contaminated with an oily sludge by use of a carrier-based hydrocarbon-degrading bacterial consortium for bioremediation. The land belonged to an oil refinery. Prior to this study, a feasibility study was conducted to assess the capacity of the bacterial consortium to degrade oily sludge. The site selected for bioremediation contained approximately 300 tons of oily sludge. The plot was divided into four blocks, based on the extent of contamination. Blocks A, B, and C were treated with the bacterial consortium, whereas Block D was maintained as an untreated control. In Block A, at time zero, i.e., at the beginning of the experiment, the soil contained as much as 99.2 g/kg of total petroleum hydrocarbon (TPH). The application of a bacterial consortium (1 kg carrier-based bacterial consortium/10 m² area) and nutrients degraded 90.2% of the TPH in 120 days, whereas in block D only 16.8% of the TPH was degraded. This study validates the large-scale use of a carrier-based bacterial consortium and nutrients for the treatment of land contaminated with oily sludge, a hazardous hydrocarbon waste generated by petroleum industry. Received: 20 October 2000 / Accepted: 22 March 2001     

Response of pigeon pea cultivars to water stress

Decrease in soil water potential during vegetative and flowering stages of two cultivars of pipeon pea (Cajanus cajari) caused higher decrease in relative water content in cv. ICPL-151 than in cv. H-77-216. Both cultivars showed partial recovery during rehydration. Cv. H-77-216 also accumulated more proline and carbohydrates during stress and showed better drought tolerance than cv. ICPL-151.     

Tetramethylpyrazine Attenuates Cognitive Impairment Via Suppressing Oxidative Stress,Neuroinflammation, and Apoptosis in Type 2 Diabetic Rats

Cognitive dysfunction is an important complication observed in type 2 diabetes mellitus (T2DM) patients. Tetramethylpyrazine (TMP) is known to exhibit anti-diabetic and neuroprotective properties. Therefore, the present study aimed to investigate the possible therapeutic effects of TMP against type 2 diabetes-associated cognitive impairment in rats. High-fat diet (HFD) followed by a low dose of streptozotocin (35 mg/kg) was used to induce diabetes in Sprague–Dawley rats. TMP (20, 40, and 80 mg/kg) and Pioglitazone (10 mg/kg) were administered for 4 weeks. The Morris water maze (MWM) and novel objective recognition task (NOR) tests were used to assess memory function. Fasting blood glucose (FBG), lipid profile, HOMA-IR, glycosylated hemoglobin (HbA1c), and glucose tolerance were measured. Acetylcholinesterase (AChE) and choline acetytransferase (ChAT) activity, acetylcholine (ACh) levels, oxidative stress, apoptotic (Bcl-2, Bax, caspase-3), and inflammatory markers (TNF-α, IL-1β, and NF-kβ) were assessed. BDNF, p-AKT, and p-CREB levels were also measured. In the present work, we observed that treatment of diabetic rats with TMP alleviated learning and memory deficits, improved insulin sensitivity, and attenuated hyperglycemia and dyslipidemia. Furthermore, treatment with TMP increased BDNF, p-Akt, and p-CREB levels, normalized cholinergic dysfunction, and suppressed oxidative, inflammatory, and apoptotic markers in the hippocampus. Collectively, our results suggest that the TMP may be an effective neuroprotective agent in alleviating type 2 diabetes-associated cognitive deficits.

     

Isolation of Three Xylanase-Producing Strains of Actinomycetes and Their Identification Using Molecular Methods

Eighty-eight actinomycetes were isolated from 20 samples collected from different locations in and around Delhi, India. Among these, 69 isolates were found positive for xylanase production. Of 69 isolates, 3 (SN32, SN77, and SN83) produced >125 IU/ml xylanase. Modern genetic tools were used for revealing the identities of these potent xylanase producers. The selected isolates were categorized under the genus Streptomyces based on their cultural and morphologic characteristics. Genetic diversity among these species of Streptomyces was established based on restriction length fragment polymorphism and random amplified polymorphic DNA analysis. The closest phylogenetic neighbours according to the 16S rRNA gene-sequence data for the three isolates SN32, SN77, and SN83 were Streptomyces cyaneus, S. tendae, and S. caelestis, respectively.     

Pretreatment of lignocellulosic material with fungi capable of higher lignin degradation and lower carbohydrate degradation improves substrate acid hydrolysis and the eventual conversion to ethanol

Phanerochaete chrysosporium, Pycnoporus cinnabarinus,and fungal isolates RCK-1 and RCK-3 were tested for their lignin degradation abilities when grown on wheat straw (WS) and Prosopis juliflora (PJ) under solid-state cultivation conditions. Fungal isolate RCK-1 degraded more lignin in WS (12.26% and 22.64%) and PJ (19.30% and 21.97%) and less holocellulose in WS (6.27% and 9.39%) and PJ (3.01% and 4.58%) after 10 and 20 days, respectively, than other fungi tested. Phanerochaete chrysosporium caused higher substrate mass loss and degraded more of holocellulosic content (WS: 55.67%; PJ: 48.89%) than lignin (WS: 18.89%; PJ: 20.20%) after 20 days. The fungal pretreatment of WS and PJ with a high-lignin-degrading and low-holocellulose-degrading fungus (fungal isolate RCK-1) for 10 days resulted in (i) reduction in acid load for hydrolysis of structural polysaccharides (from 3.5% to 2.5% in WS and from 4.5% to 2.5% in PJ), (ii) an increase in the release of fermentable sugars (from 30.27 to 40.82 g L(-1) in WS and from 18.18 to 26.00 g L(-1) in PJ), and (iii) a reduction in fermentation inhibitors (total phenolics) in acid hydrolysate of WS (from 1.31 to 0.63 g L(-1)) and PJ (from 2.05 to 0.80 g L(-1)). Ethanol yield and volumetric productivity from RCK-1-treated WS (0.48 g g(-1) and 0.54 g L(-1) h(-1), respectively) and PJ (0.46 g g(-1) and 0.33 g L(-1) h(-1), respectively) were higher than untreated WS (0.36 g g(-1) and 0.30 g L(-1) h(-1), respectively) and untreated PJ (0.42 g g(-1) and 0.21 g L(-1) h(-1), respectively).     

White-rot fungal conversion of wheat straw to energy rich cattle feed

In order to improve the digestibility and nutrient availability in rumen, wheat straw was subjected to solid state fermentation (SSF) with white-rot fungi (i.e. Pleurotus ostreatus and Trametes versicolor) and the fermented biomass (called myco-straw) was evaluated for biochemical, enzymatic and nutritional parameters. The fungal treatment after 30 days led to significant decrease (P < 0.05) in cell wall constituents viz, acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and cellulose to the extent of 35.00, 38.88, 45.00, 37.48 and 37.86%, respectively in P. ostreatus fermented straw, while 30.04, 33.85, 39.90, 31.29 and 34.00%, respectively in T. versicolor fermented straw. However, maximum efficiency of fermentation in terms of low carbohydrate consumption per unit of lignin degradation, favoring cattle feed production was observed for P. ostreatus on the 10th day (17.12%) as compared with T. versicolor on the 30th day (16.91%). The myco-straw was found to contain significantly high (P < 0.05) crude protein (CP; 4.77% T. versicolor, 5.08% P. ostreatus) as compared to control straw (3.37%). Metabolizable energy (ME, MJ/kg DM), percent organic matter digestibility (OMD) and short chain fatty acids (SCFAs; mmol) production also increased considerably from control straw (4.40, 29.91 and 0.292) to a maximum up to P. ostreatus fermented straw (4.92, 33.39 and 0.376 on 20th day) and T. versicolor fermented straw (4.66, 31.74 and 0.334 on 10th day), respectively. Moreover, the myco-straw had lower organic carbon and was rich in nitrogen with lower C/N ratio as compared to control wheat straw. Results suggest that the fungal fermentation of wheat straw effectively improved CP content, OM digestibility, SCFAs production, ME value and simultaneously lowered the C/N ratio, thus showing potential for bioconversion of lignin rich wheat straw into high energy cattle feed.     

Hydrolytic potential of extracellular enzymes from a mutant strain of Fusarium oxysporum

Potential of extracellular enzymes of a mutant strain (NTG-19) of Fusarium oxysporum in hydrolysis of cellulosic materials was investigated. The enzyme preparation effectively hydrolyzed untreated as well as chemically pretreated sugarcane bagasse. About 95% hydrolysis could be achieved with sodium sulfite pretreated bagasse within 96 h. The enzymes exhibit appreciable stability during the course of hydrolysis.