The assessment of good and bad bacteria in holy basil(Ocimum sanctum)leaves

Holy basil(Tulsi,Ocimum sanctum)is considered to be a pious plant.It is used not only in many of the rituals of Hindus but is also known for its innumerable medicinal qualities.Holy basil leaves(HBLs)are often consumed raw thus it is pertinent to detect the bacteria on Tulsi leaves.This study was conducted to understand the diversity of the aerobically growing microbiome of edible holy basil leaves.A total of 112 samples of leaves were collected from households of six localities in and around Bareilly,India for detecting culturable bacteria growing aerobically.A sum of 579 bacterial isolates belonging to 106 different species was identified.Pantoea agglomerans isolates were detected in 43 samples followed by isolates Virgibacillus pantothenticus(21),Bacillus coagulans(18),Bacillus cereus(17),Geobacillus stearothermophilus(16),Klebsiella pneumoniae(13),Citrobacter freundii(12),Lysinibacillus sphaericus(12),Acinetobacter calcoaceticus(11),Escherichia coli(11),and Xenorhabdus bovienii(11).Isolates of 95 species of bacteria were detected on<10 samples of HBLs.Of 579 isolates,161 isolates detected in 68(60.71%)samples were of putatively good bacteria belonging to eight genera(Bacillus,Brevibacillus,Lysinibacillus,Paenibacillus,Photobacter,Siccibacter,Virgibacillus,Xenoirhabdus)and 23 species.However,418 bacterial isolates detected in 108(96.43%)of the HBL samples were classified as potentially pathogenic for humans and animals belonging to 34 genera and 73 species.There were only four samples(three from Mahanagar and one from Bhojipura)that had no potential pathogenic bacteria detected in this study.The analysis indicated that HBL leaves from the ICAR-IVRI campus had a lower probability(P<0.04)of harbouring good bacteria than samples from Bhojpura,Mahanagar,North City and Rajendra Nagar.Cinnamaldehyde inhibiting 96.72%of the isolates and carvacrol inhibiting 96.37%of the isolates were the best herbal antimicrobials and among antibiotics,meropenem inhibited 98.96%of bacterial isolates.Antimicrobial resistance in non-pathogenic or good bacteria was significantly more common(P<0.01)for ajowan oil but they were more often(P<0.05)susceptible to holy basil oil,lemongrass oil,citral,P.embalica leaf extract,P.longifolia seed oil,nitrofurantoin,ciprofloxacin,chloramphenicol,colistin and minocycline than isolates of potentially pathogenic bacteria.The study concludes that HBLs may harbour both good and bacteria,and should be consumed raw only after proper decontamination.

The rpoS deficiency suppresses acetate accumulation in glucose-enriched culture of Escherichia coli under an aerobic condition

The role ofEscherichia coli rpoS on the central carbon metabolism was investigated through analyzing the deficiency of this regulon gene under aerobic and glucose- enriched culture conditions. The experimental results showed that while the wild type cells exhibited an overflow metabolism effect, the rpoS-deleting mutation alleviated this effect with the significant suppression of acetate accumulation under a high glucose condition. This gene deletion also induced the twofold upregulation ofgltA and one-tenth downregulation of poxB, respectively. The overflow metabolism effect was confirmed to be recovered by re-introducing rpoS gene into the mutant. These results demonstrated rpoS changed the central carbon metabolism toward acetate overflow through dehydrogenation of pyruvate and reduction of TCA cycle activity.

Cultivation of gut microorganisms of the marine ascidian Halocynthia roretzi reveals their potential roles in the environmental adaptation of their host

It has long been known that abundant symbiotic bacteria exist in the tunic and gut of marine ascidians,and that these play crucial roles in host development,physiological metabolism,and environmental adaptation.However,the identity,roles and functions of these symbiotic bacteria are known for only a few strains.In this study,we isolated and cultivated 263 strains of microorganisms from the intestine of the marine ascidian Halocynthia roretzi through a combination of aerobic and anaerobic culture approaches.Most cultivated species,both aerobic and anaerobic,from ascidian stool samples belonged to the genus Bacillus based on 16S rDNA sequencing identification and phylogenetic assays.The distribution of cultured bacteria varied with seasonal changes in environmental conditions.To explore the functions of cultured bacteria,we screened out a strain of Serratia sp.whose extracts showed high antibacterial activity against aquatic pathogens.These findings revealed the potential roles of gut microorganisms in ascidian defense and environmental adaptation,thus providing insights into the interaction and co-evolution between gut bacteria and their hosts.