Microbial degradation of plastics: Biofilms and degradation pathways

Plastics are recalcitrant polymers released in the environment through unpredicted use leading to accumulation and increased water and soil pollution. Transportation of these recalcitrant polymers in agricultural soil, sediment, and water has been causing concerns for environmentalists. Biofilm community adhered on plastic polymers have a significant contribution in their degradation as they warrant bioavailability of substrates, sharing of metabolites and increased cell viability thereby accelerating biodegradation. Metabolic enzymes of the microbes can be exploited as a potent tool for polymer degradation. However very little or no reports are available about the influence of biofilm and plastic degradation and vice versa. The present chapter reports the impact of biofilm microbes in the degradation of commonly used plastics. Furthermore, potent microorganisms and their interactions with the plastic surface has been deciphered, which would serve as a better understanding of the utilization of biofilm-based methods in the development of plastic waste management

Impact of heavy metal contamination in different soil towards microbial characteristics and nutrient availability

An intensive investigation for detecting source of the heavy metals contamination in different areas (within industry, at roadside, adjacent agriculture lands) of various industries located at two sites A & B were made. Co-relationshipswere determined for specificmetal contamination in leacheates at sites with total contents of heavy metal at source.At siteA, it was observed that the leached fractions were highly correlated with the total contents of all tested heavy metals showing same source of contamination, whereas at site B relation was obtained only in case of Mn i.e 0.99, Zn i.e 0.82 and 0.70 for Cu, while, rest had sparse relationship, showing that the variability in heavy metal contents was caused by the different sources of contamination. The soil samples showed different microbial groups (cfu), in the order Bacteria > Fungi > Actinomycetes > RhizobiumandAzotobacters. The results indicated that the lowavailability of nutrients (NPK) in soil could be due to the heavy metal contamination which reduced the beneficial microbes such as Rhizobia and Azotobacters in contaminated soil

ANTIBIOFOULING BIOMATERIALS

Antifouling refers to the process of control of fouling which occurs on liquid-solid surfaces. The term ‘fouling’ indicates an undesirable natural succession process during biofilm formation, in which a submerged surface or membranes becomes encrusted with material from the surrounding environment. It mainly involves microorganisms and their by-products developed on the surface by conditioning, attachment, biofilm formation followed by colonization. The accumulation of micro and macrofoulers on immersed structures results in economic as well as environmental losses. It is one of the major vulnerable problems currently disturbing many ecological niches as well as in shipping and other industrial aquatic processes. The existence of natural antifouling agents or biomaterials provides sustainable eco-friendly control and hence remains a challenge for future researchers. The use of biological tools for control of fouling is gaining importance day by day

Bactria Associated with Non-Alcoholic Fermented Bamboo Food Product

Pure bacterial cultures were isolated from fermented products collected from two locations of North East India (Assam and Arunachal Pradesh). Forty four variants were identified by 16S rRNA gene sequencing. The dominant microbial genera found were Bacillus, Paenibacillus followed by Oceanobacillus and Lactobacillus in Assam and Bacillus, Enterococcus, Lactobacillus in Arunachal-Pradesh food products. Bacillus isolates showed extracellular enzyme production (amylases, proteases and lipases) as analyzed through plate assay. GC-MS analysis showed beneficial chemical components like organic acids, esters, aminoacids, vitamins in fermented bamboo shoot products. Probiotic attributes of culturable bacterial isolates from bamboo fermentations gives promiscuity for human consumption. Beneficial microorganisms from bamboo shoot fermented food products of North-Eastern region of India were explored and compared using bioinformatics tools

BACTERIA ASSOCIATED WITH NON-ALCOHOLIC FERMENTED BAMBOO SHOOT FOOD PRODUCT

Pure bacterial cultures were isolated from fermented products collected from two locations of North East India (Assam and Arunachal Pradesh). Forty four variants were identified by 16S rRNA gene sequencing. The dominant microbial genera found were Bacillus, Paenibacillus followed by Oceanobacillus and Lactobacillus in Assam and Bacillus, Enterococcus, Lactobacillus in Arunachal-Pradesh food products. Bacillus isolates showed extracellular enzyme production (amylases, proteases and lipases) as analyzed through plate assay. GC-MS analysis showed beneficial chemical components like organic acids, esters, aminoacids, vitamins in fermented bamboo shoot products. Probiotic attributes of culturable bacterial isolates from bamboo fermentations gives promiscuity for human consumption. Beneficial microorganisms from bamboo shoot fermented food products of North-Eastern region of India were explored and compared using bioinformatics tools

Degradation kinetics of resorcinol by Enterobacter cloacae isolate

Resorcinol was utilized as the sole carbon and energy source by Enterobacter cloacae (identification by 16S rDNA nucleotide sequencing Genbank Accession Number JN093148). The different concentration of resorcinol utilized by the bacterial isolate ranged between 55 and 220 mg l-1 at 30°C and pH of 7.0. It was observed that the batch experimental results were best fitted for Michaelis-Menten and Monod models (for 220 mg l-1 resorcinol) with time under defined conditions. The kinetics constants for the Michaelis-Menten equation (enzyme kinetics) were Km = 11.00 mM and Vmax = 0.03 mM min-1 and for the Monod equation (growth kinetics) was μmax = 0.0371 h-1 in the inhibitory region and KS = 22.09 mg l-1. It was assumed that enzyme reactions limit biomass production (Monod kinetics) during resorcinol degradation by E. cloacae. The enzyme kinetic model (Michaelis-Menten) used was fit to the resorcinol degradation profiles with a set of model parameters such as using pre-induced E. cloacae cells on 220 mg l-1 resorcinol

Detection of Porphyromonas gingivalis and Treponema denticola in chronic and aggressive periodontitis patients: A comparative polymerase chain reaction study

The detection frequency of Porphyromonas gingivalis and Treponema denticola in chronic periodontitis (CP) and aggressive periodontitis (AgP) is not explored well in Indian population. Aim: The study was undertaken to detect P. gingivalis and T. denticola in CP as well as in AgP patients using polymerase chain reaction (PCR), and to determine the relationship between the frequency of these two microorganisms and the severity of clinical periodontal parameters. Materials and Methods: Subgingival plaque samples were collected from ninety participants (thirty CP patients, thirty AgP patients, and thirty healthy participants) and the aforementioned two microorganisms were detected using PCR. Results: However, when CP and AgP were compared for the detection frequency of two microorganisms, no statistically significant difference was noted. A statistically significant increase in the number of bacteria‑positive sites increased as the score of plaque index (PI), gingival index (GI), and clinical attachment level of CP and AgP patients increased. Coexistence of P. gingivalis and T. denticola was frequently observed in deep periodontal pockets. Conclusions: Study findings suggest that P. gingivalis and T. denticola are significantly associated with the severity of periodontal tissue destruction. Statistically significant association exists between clinical periodontal parameters such as PI, GI, periodontal pocket depth (PPD), and clinical attachment loss and presence of both the microorganism

Arid ecosystem: future option for carbon sinks using microbial community intelligence

Desert, comprising one-third of the Earth’s surface, was a synonym for ‘no life’ as it supports very less or no life due to nutritional stress and extreme weather. Microbial autotrophic biochemistry is the principal source of carbon in arid environment, but understanding of these processes in arid ecosystem is limited. Emerging molecular tools have identified associations of phototrophic and chemolithoautotrophic communities often termed as ‘biological soil crust’ or ‘microbiotic crust’. They are the sole sources of carbon and nitrogen, collectively providing soil stability to support vegetation. Here the curiosity arises, whether this phenomenon could be exploited in deserts for carbon sink using microbial community intelligence. By following the precipitation event under regulated nutrient supply that promotes the soil microbial intelligence for autotrophy would enrich soil carbon and nitrogen which in turn support plant growth in desert. Additionally, bioaugmentation of rhizobacteria could enhance the process. This will enable us to refine and formulate our strategies to exploit CO2-fixing microorganisms in such niches vis-à-vis supporting the carbon sink using microbial community intelligence

Genome Sequence of Lactobacillus plantarum EGD-AQ4, Isolated from Fermented Product of Northeast India

We present a draft genome sequence of Lactobacillus plantarum strain EGD-AQ4, isolated from nonalcoholic fermented bamboo shoot products of Northeast India. The size of the draft genome sequence is the largest among all the reported genome sequences of Lactobacillus plantarum, thus enabling the exploration of new gene clusters involved in various functional and probiotic attributes

Enhanced expression of catechol 1,2 dioxygenase gene in biofilm forming Pseudomonas mendocina EGD-AQ5 under increasing benzoate stress

In natural settings, microbes often associate closely with surfaces and interfaces called biofilms and adhere in an extracellular matrix. The biofilm provide diverse microenvironments and high resistance to environmental stress on the constituent cells that aid to generate cellular heterogeneity and phenotypic variability. The work presented here examines for the first time the capability of Pseudomonas mendocina EGD-AQ5 biofilm-associated cells, compared with that of planktonic cells to utilize toxic intermediate catechol under benzoate degradation conditions in liquid culture systems. Both planktonic and biofilmassociated cells utilized benzoate to the same extent but accumulated catechol differently. This differential catechol accumulation activity of the Pseudomonas mendocina EGD-AQ5 could be accredited to the cells adapted as a biofilm. Further experiments with transcriptome implicated to increased expression of genes like pelA (involved in biofilm formation) cat1,2D (ortho pathway) and decreased expression of cat2,3D (meta pathway) in biofilm harvested cells than free suspended cells. Whole genome sequence analysis of Pseudomonas mendocina EGD-AQ5 (Genbank Accession No AVQF00000000) deciphered catechol ortho and meta-pathways for benzoate utilization and pelABCDEFG as involved in biofilm formation. These results suggest that Pseudomonas mendocina EGD-AQ5 biofilms should facilitate bioaugmentation to be more resilient and efficient bioremediation technology than free suspended planktonic cells