Isolation, characterization and optimization of bacterial isolate SARR1 for biodegradation of pretreated low density polyethylene

Accumulation of low-density polyethylene (LDPE) has caused a threat to the environment because of its stable and inert nature as it cannot be degraded easily by microorganisms. Its lightweight, low cost, strength, durability, and its various other applications, have led to the wide usage of the polymer, which is exerting a negative effect on both marine and land biota. The development of an eco-friendly or a promising strategy is needed to reduce LDPE waste from both land and water. In the present study, observations have been made to isolate highly efficient LDPE degrading bacteria. The response surface methodology (RSM) was used to predict the best optimization of media for the degradation of LDPE by isolate SARR1. The isolate SARR1 was selected through primary screening by weight loss method and secondary screening using CO2 evolution test, TTC and MATH Test. The isolate SARR1 showed 6.30 ± 0.25 g/L CO2 evolution. The microbial adhesion hydrophobicity (MATH) was observed during log phase (100 to 56.89 ± 0.97 %) and stationary phase (100 to 82.92 ± 1.24 %). An isolate SARR1 converted the TTC into red coloured insoluble triphenyl formazan (TPF) after incubation of 7 days. The isolated bacteria SARR1 showed 38.3 ± 1.27 % biodegradation efficiency in the pretreated LDPE strips at 37 °C and pH 7.0 under optimized conditions within 30 days of incubation. This bioremediation and biodegradation approach is eco-friendly and safe for the environment. The results of treatment with isolate SARR1 had a potential hope to degrade LDPE at higher rate than natural degradation. 

Physiological and biochemical responses of seedlings of six contrasting barley (Hordeum vulgare L.) cultivars grown under salt-stressed conditions

Salinity stress affects plant growth and development and underlying metabolisms. To mitigate the effects of the stress, plants responded by changing their physiological and biochemical activities and withstand the stress. The present study aimed to determine barley's (Hordeum vulgare L.)  physiological and biochemical response to salinity stress conditions for 7 days and 14 days. Six barley cultivars (Alfa93, DWRB73, DL88, NB1, NB3, NDB1173) were grown under controlled conditions, and different level of salinity stress was applied. In addition, seedling growth, physiological and biochemical parameters, plant leaves RWC, and electrolyte leakage were analyzed. The overall seedling growth, RWC, and electrolyte leakage in salt susceptible lines Alfa93 and DWRB73 were low than the salt-tolerant barley lines (DL88, NB1, NB3, and NDB1173). Electrolyte leakage was 26.0 and 20.6% in Alfa93 and DWRB73, whereas it was 17.6, 14.6, 15.3, and 10.4% in DL88, NB1, NB3, and NDB1173, respectively at 300 mM salinity stress.  The loss of photosynthetic pigments under salt stress was high in susceptible lines, salinity treated (300 mM NaCl) Alfa93 plants exhibit 49.5% and 59.5% of Chl-a than control plants after 7 and 14 days of treatment, respectively. However, at 300 mM stress level, NB1 (ST) showed less Chl-a loss after 7 days, whereas NDB1173 showed less reduction in Chl-a after 14 days.  Antioxidant enzymes such as SOD, POX, CAT, and APX activities in susceptible line Alfa93 and DWRB73 were lower than tolerant lines. PCA analysis demonstrated a positive correlation between antioxidant enzyme activities and genotypes under salinity stress. PCA analysis described DL88 as the most tolerant, and DWRB73 was the most salt susceptible genotype among the studied barley genotypes. The present findings suggest that barley cultivars' physiological and biochemical activities under salinity stress conditions may be used to screen salt-tolerant crops

Proteome Profiling of Seed Storage Proteins Reveals the Nutritional Potential of Salicornia brachiata Roxb., an Extreme Halophyte

Salicornia brachiata is an extreme halophyte that grows in salty marshes and is considered to be a potential alternative crop for seawater agriculture. <i>Salicornia</i> seeds are rich in protein, and its tender shoots are eaten as salad greens. Seed storage proteins were fractionated by sequential extraction using different solvents, including distilled water for albumins, NaCl (1.0 M) for globulins, NaOH (0.1 N) for glutelins, and ethanol (70% v/v) for prolamins. Globulins accounted for 54.75% of the total seed storage proteins followed by albumins (34.30%) and glutelins (8.70%). The fractionated proteins were characterized using 2D-diagonal SDS-PAGE and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. The globulin fraction, composed of seven intermolecular disulfide-linked polypeptide pairs of molecular mass 63.5, 62.5, 54.7, 53.0, 43.2, 38.5, and 35.1 kDa, encompassed a basic and an acidic subunit. Two-dimensional gels revealed approximately 32 spots, with isoelectric points and molecular masses ranging from 4.93 to 11.6 and from ∼5.2 to ∼109.4 kDa, respectively. Protein spots were identified by MALDI-TOF MS peptide mass fingerprint analysis and further classified. Homology analysis demonstrated that 19% of the proteins were involved in metabolism, 16% were involved in signaling, and 15% were regulatory proteins. Peptide mass fingerprint analysis confirmed the presence of inter- and intramolecular disulfide linkages in the globulin fraction. Sulfur-rich proteins are of high nutritional value, and disulfides make <i>S. brachiata</i> a potential source of dietary supplementation