Sodium carbonate pretreatment: an approach towards desilication of paddy straw and enhancement in biogas production

Lignocellulosic biomass is a useful but an inconvenient form of energy, and paddy straw (PS) is one of the most abundant lignocellulosic wastes on the earth. Lignocellulosics generally have a high content of cellulose having combustion energy of 15 kJ/g which, when converted to methane, have a combustible energy of 50 kJ/g. But lignin and silica are the main deterrents for the microbial action on the cellulose/hemi-cellulose component of PS. In order to break the protective shield made by lignin and silica and to enhance the PS digestibility, the PS was pretreated with different concentrations (2, 4, 6, 8 and 10 %) of sodium carbonate by soaking the PS in sodium carbonate solution for the periods of 24 and 48 h and simultaneously irradiating the other set with microwaves (power 720 W, temperature 180 °C) for 30 and 60 min. The change in chemical composition of PS was the factor determining the enhancement in PS digestibility. Sodium carbonate (4 %) + microwave (60 min) pretreatment was found to be the best amongst the other pretreatments with 84.9 % desilication of PS and 44.3 and 54.4 % increase in cellulose and biogas production, respectively.     

Value-addition of agricultural wastes for augmented cellulase and xylanase production through solid-state tray fermentation employing mixed-culture of fungi

Solid-state fermentation (SSF) was performed to evaluate the potential of agricultural residues for the production of cellulase and hemicellulase using individual and mixed cultures of Aspergillus niger and Trichoderma reseei. The maximum filter paper (FP) cellulase activity of 13.57 IU/gram dry substrate (gds), 22.89 IU/gds and 24.17 IU/gds and β-glucosidase activities of 21.69 IU/gds, 13.58 IU/gds and 24.54 IU/gds were obtained with wheat bran medium at 96 h incubation period with A. niger, T. reseei and mixed-cultures of A. niger and T. reseei, respectively. Mixed-culture SSF using rice straw supplemented with wheat bran in the ratio 3:2 resulted in higher FP cellulase, β-glucosidase, endoglucanase (CMCase) and xylanase activities, compared to the activities obtained using mono-cultures. Similarly, higher FP cellulase, β-glucosidase, CMCase and xylanase activities of 35.8 IU/gds (96 h), 33.71 IU/gds (96 h), 131.34 IU/gds (120 h) and 3106.34 IU/gds (120 h) were achieved in the tray fermentation using rice straw with wheat bran in the ratio of 3:2. Results of present investigation showed that higher cellulase activity and an optimal combination of cellulase and β-glucosidase can be achieved through mixed-culture SSF in trays. The approach of utilizing negative cost agricultural wastes through tray fermentation for cellulase and hemicellulase production is expected to serve the objectives of: (a) management of wastes which would otherwise cause environmental pollution problems; (b) production of hydrolytic enzymes at low cost and; (c) simple technique requiring no sophisticated instruments with practical applications.     

Chilled Storage of High Pressure Processed Black Tiger Shrimp (Penaeus monodon)

The effect of high pressure (HP) treatment (at 100, 270, and 435 MPa for 5 min at 25°C) on microbiological (total viable count and total psychrotrophic count), physical (color, texture, and drip loss), and microstructural characteristics of black tiger shrimp (Penaeus monodon) during storage at 2°C for 35 days was investigated. Pressure treatment increased drip loss, maintained low microorganisms level, imparted cooked appearance to the muscle, and resulted in improved texture. Results of scanning electron microscopy revealed more compact structure in treated samples, confirming the results of texture profile analysis. Pressure treatment of 435 MPa was most effective in preserving the quality of shrimp.     

Carbohydrate degrading enzyme production by plant pathogenic mycelia and microsclerotia isolates of Macrophomina phaseolina through koji fermentation

The ability of hydrolytic enzyme production by two different isolates of Macrophomina phaseolina was studied on apple pomace as a substrate for solid state fermentation (SSF). Initial moisture level, temperature and fermentation period was optimized so as to achieve higher output. Among the two different isolates, microsclerotial (MphP) and mycelial (MphM), MphP was observed as a potential source of different hydrolytic enzymes as compared to MphM. MphP gave higher enzyme activities (IU/gram dry substrate (gds): filter paper cellulase (FPase) activity 196.21 ± 16.3 (120 h), carboxymethyl cellulase (CMCase) 279.34 ± 28.25 (72 h), β-glucosidase (BGL) 129.82 ± 12.41 (96 h), xylanase 2527.88 ± 46.15 (120 h), and amylase 2780.72 ± 38.13 (96 h), respectively at 70% (v/w) IML. The incubation temperature was also found to have impact on the enzyme production ability of Macrophomina strains. The higher enzyme activities were achieved (IU/gds) as follows FPase 276.13 ± 25.02 (40 °C, 120 h), CMCase 278.11 ± 24.47 (35 °C, 144 h), BGL 189.47 ± 15.05 (30 °C, 144 h), xylanase 3845.77 ± 43.38 (35 °C, 144 h) and amylase activity of 3309.45 ± 29.22 (35 °C, 120 h), respectively using MphP at 70% (v/w) IML. This study reports for the first time the potential of carbohydrate degrading enzyme bioproduction by different isolates of M. phaseolina.     

Molecular detection and typing of Mycobacterium avium subspecies paratuberculosis from milk samples of dairy animals

Genotyping of Mycobacterium avium subspecies paratuberculosis (MAP) is important for precise classification of bacterium and for understanding the molecular epidemiology. The present study reports detection and typing of the MAP from milk. On the basis of clinical signs of diarrhea and/or weakness, the dairy animals suspected for Johne’s disease were screened by Ziehl–Neelsen staining of fecal samples. The milk samples from 13 selected animals were processed for DNA extraction and direct IS900 polymerase chain reaction (PCR). MAP identified by IS900 PCR was genotyped using IS1311 PCR-restriction endonuclease analysis (REA). IS900 milk PCR revealed 30.8% animals positive for MAP, including 40% of the moderate and 50% of the heavy fecal shedders. All infected animals showed Bison type MAP in IS1311 PCR-REA. IS900 PCR can be used for screening of milk for MAP; however, the method needs to be evaluated for subclinical cases. IS1311 PCR-REA results indicated the predominance of Bison type MAP in the dairy animals of this region.     

Chronic response of Anabaena fertilissima Rao, C.B. on growth, metabolites and enzymatic activities by chlorophenoxy herbicide

Study was carried out to investigate the chronic response of cyanobacteria, Anabaena fertilissima to chlorophenoxy herbicide 2,4-dichlorophynoxyacetic Acid (2,4-D) ethyl ester at different concentrations 15, 30 and 60 ppm. The influence of 2,4-D on growth (pigments), release of metabolites such as carbohydrates, protein, amino acid, phenols and nitrate reductase and glutamine synthetase activities was analyzed. The test concentrations caused a concentration-dependent decrease in pigments. Depletion in carbohydrate and protein content was registered with rise in herbicide concentrations. However, phenols were found to rise with increased herbicide concentrations but amino acids were reported to decline. The inhibition of nitrate reductase and glutamine synthetase activity was also concentration-dependent and showed more sensitivity for substituted phenoxy herbicide. This study therefore suggests that decrease in metabolite content and enzyme activity can be used as a signal of herbicide toxicity in cyanobacteria.     

Why grain yield of transplanted rice on permanent raised beds declines with time?

Permanent raised beds are being promoted as a resource conservation technology for rice–wheat systems in Indo-Gangetic plains (IGP) to improve the water productivity of rice and wheat in addition to other benefits, as furrow irrigation can be more efficient than flood irrigation. However, several studies carried out in the NW IGP have shown rice grain yields to decrease with the increasing age of the beds. The present study was conducted on a deep alluvial loam (Ustochrept) in a farmer's field at Phillaur, Punjab, India, to identify possible reasons for the declining grain yield of rice on the permanent raised beds (37.5 cm wide alternating with 30 cm wide furrows 15 cm deep) in comparison to fresh raised beds. The beds were formed with a bed planter drawn by a 35-hp 4-wheel tractor, which was also used to direct drill wheat on the permanent beds each year, and to reshape the beds prior to each rice crop. This paper reports a study of rice root distribution and mass at the end of the vegetative stage, and soil bulk density after harvest, for transplanted rice on permanent beds (4th rice crop, 8th crop) in comparison with transplanted rice on fresh beds (1st crop).Rice grain yield declined linearly with increasing age of the permanent beds. It decreased by 19% in 2004, 45% in 2005 and 59% in 2006 from 4.64 t ha⁻¹ in 2003. In situ exposure of root profiles on permanent and fresh beds revealed that the horizontal spread of roots on permanent beds (6 cm from the base of the plant at 18 cm depth and 12 cm at 27 cm depth) was much less than on fresh beds (12 cm at 18 cm depth and 18 cm at 27 cm depth). The root mass density in at 0–15 cm the middle of the fresh beds was 59% higher than on the permanent beds. Bulk density was significantly higher under the shoulder and side of the permanent beds to the depth of sampling (0–15 cm) than under the fresh beds at the same positions across the furrow. The decline in performance of rice on beds as the beds aged was at least partly due to compaction of the permanent beds by the tractor tyres, which had width similar to that of the top of the furrow. This hindered the spread of the roots particularly towards the beds.     

Effect of Alternaria alternata on the coccinellid pest Henosepilachna vigintioctopunctata and its implications for biological pest management

Twenty-eight spotted potato ladybird beetle (Henosepilachna vigintioctopunctata) is a polyphagous pest that infests various crop plants of the family Solanceae. It extensively infests Withania somnifera, a high-value medicinal plant of this family. Both the beetle and W. somnifera leaf spot pathogen (Alternaria alternata) are individually found to be closely associated with the foliar damage and may rarely infest the same leaf simultaneously. Beetles fed on diseased leaves showed high pupal and larval mortality. Furthermore, the development of the larvae into pupa and from pupa to adult was also delayed, which in turn delayed the overall development of the insect. Adult emergence from pupae is also reduced in the insects fed on diseased leaves. Since the fungal pathogen is host specific to W. somnifera and does not infect the other solanaceous crops, therefore this fungal stain can be used in designing bio-control strategies for the other solanaceous plants frequently infested by the beetle.